NOT YET RELEASED 37208-E0 MechanicalSystems CG ED2 PR2€¦ · Lab-Volt License Agreement By using the software in this package, you are agreeing to become bound by the terms of this

Tech-World Manufacturing

Mechanical Systems

Level one CELL Guide

Edition 2

37208-E0

SECOND EDITION

Second Printing, May 2007

Copyright 2005 Lab-Volt Systems, Inc.

All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted in any form by any means, electronic, mechanical, photocopied, recorded, or otherwise, without prior written permission from Lab-Volt Systems, Inc.

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Table of Contents

i

Introduction ................................................................................................................ 1

Selecting Procedures to Perform............................................................................... 2

Topic 1 – Introduction to Mechanical Systems.................................................... 3 Activity 1 – Mechanical Systems Basics .................................................................. 4 Activity 2 – Work Experiences.................................................................................. 5 Activity 3 – Make Your Future ................................................................................. 6

Topic 2 – The Parts of a Hydraulic Circuit........................................................... 7 Activity 1 – Diagram Reading................................................................................... 8 Activity 2 – Trainer Components.............................................................................. 9 Activity 3 – Trainer Introduction ........................................................................... 10

Hardware Procedure: General Inspection.......................................................... 10

Topic 3 – Assemble and Operate a Circuit.......................................................... 11 Activity 1 – Operating Safety ................................................................................. 12

Hardware Procedure: Specifying the Bending Limit of a Hydraulic Hose....... 12 Hardware Procedure: Testing the Connection Fittings..................................... 12 Hardware Procedure: Safety Precautions.......................................................... 13 Hardware Procedure: When Running the Power Unit...................................... 13 Hardware Procedure: Stopping the Power Unit ................................................ 13 Hardware Procedure: Removing and Inspecting Quick-Connect Hydraulic Hoses.................................................................................................................... 14 Software Procedure: Software Overview............................................................ 15 Software Procedure: Tool Functions .................................................................. 15 Software Procedure: Equipment Views.............................................................. 16 Software Procedure: Equipment Installation .................................................... 17

Activity 2 – Component Installation....................................................................... 18 Hardware Procedure: Flexible Hose Connection ............................................... 18 Hardware Procedure: Ending the Activity......................................................... 19 Software Procedure: Flexible Hose Connection ................................................. 19 Software Procedure: Making Electrical Equipment Connections..................... 22

Activity 3 – System Operation ................................................................................ 26 Hardware Procedure: Preparing the Power Unit .............................................. 26 Hardware Procedure: Preparing for Safe Operation ......................................... 26 Hardware Procedure: Power Unit Operation .................................................... 27 Hardware Procedure: Ending the Activity......................................................... 28

Table of Contents

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Topic 4 – Fundamental Concepts.......................................................................... 29 Activity 1 – Static Pressure .................................................................................... 30

Hardware Procedure: Static Pressure Simulator .............................................. 30 Activity 2 – Pump Head .......................................................................................... 31

Hardware Procedure: Pump Head Simulator.................................................... 32

Topic 5 – Test a Circuit ........................................................................................... 33 Activity 1 – System Measuring............................................................................... 36

Hardware Procedure: Install the Components by Following a Connection Diagram............................................................................................................... 37 Hardware Procedure: Installing a Flow Control Valve ..................................... 39 Hardware Procedure: Recording the Pressure and Flow .................................. 39 Hardware Procedure: Cleanup ........................................................................... 40 Software Procedure: Install the Components by Following a Connection Diagram............................................................................................................... 41 Software Procedure: Installing a Flow Control Valve ....................................... 45 Software Procedure: Recording the Pressure and Flow .................................... 46

Activity 2 – Efficiency.............................................................................................. 47 Hardware Procedure: Preparing the Trainer .................................................... 48 Hardware Procedure: Running the Power Unit ................................................ 49 Hardware Procedure: Adjusting the Pressure................................................... 49 Hardware Procedure: Pressure and Flow Analysis ........................................... 50 Hardware Procedure: Computing Friction Loss ................................................ 50 Hardware Procedure: Cleanup ........................................................................... 50 Software Procedure: Preparing the Trainer ...................................................... 52 Software Procedure: Adjusting the Pressure..................................................... 53 Software Procedure: Pressure and Flow Analysis ............................................. 54 Software Procedure: Computing Friction Loss .................................................. 54

Topic 6 – Circuit Control ........................................................................................ 55 Activity 1 – Meter-In Control.................................................................................. 57

Hardware Procedure: Preparing the Meter-In Circuit...................................... 58 Hardware Procedure: Adjusting the Controls ................................................... 58 Hardware Procedure: Moving the Actuator....................................................... 58 Hardware Procedure: Placing a Control Upstream........................................... 59 Software Procedure: Adjusting the Controls in a Meter-In Circuit.................. 60 Software Procedure: Moving the Actuator......................................................... 62 Software Procedure: Placing a Control Upstream............................................. 63

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Activity 2 – Meter-Out Control ............................................................................... 66 Hardware Procedure: Preparing the Meter-Out Circuit ................................... 67 Hardware Procedure: Adjusting the Controls ................................................... 67 Hardware Procedure: Moving the Actuator....................................................... 68 Hardware Procedure: Placing a Control Downstream ...................................... 68 Software Procedure: Preparing the Meter-Out Circuit ..................................... 69 Software Procedure: Adjusting the Controls ..................................................... 70 Software Procedure: Moving the Actuator......................................................... 71 Software Procedure: Placing a Control Downstream ........................................ 71

Topic 7 – Levers ........................................................................................................ 73 Activity 1 – Leverage............................................................................................... 74

General Procedure: An Experiment in Balance................................................. 74 General Procedure: An Experiment in Balance and Mechanical Advantage... 74

Activity 2 – Cranes and Prizes................................................................................ 75 General Procedure: Repeating the Experiment in Balance and Mechanical Advantage............................................................................................................ 75 General Procedure: A Second Experiment in Balance and Mechanical Advantage............................................................................................................ 75

Activity 3 – Wheelbarrows and Bottle Openers ..................................................... 76 General Procedure: An Experiment with a Second-Class Lever ...................... 76

Activity 4 – Catapults and Fishing Rods................................................................ 78 General Procedure: An Experiment with a Third-Class Lever......................... 78

Topic 8 – Resistance................................................................................................. 79 Activity 1 – The Exploring Mechanisms Trainer................................................... 81 Activity 2 – Static Friction...................................................................................... 82

General Procedure: Weighing the Object ........................................................... 82 General Procedure: Measuring Static Friction.................................................. 83

Activity 3 – Dynamic Friction................................................................................. 84 General Procedure: Measuring Dynamic Friction............................................. 84

Topic 9 – Drives......................................................................................................... 85 Activity 1 – Friction Drives..................................................................................... 86

General Procedure: Safe Operation.................................................................... 86 General Procedure: Removing the Pulleys and Belt ......................................... 87 General Procedure: Installing the Friction Pulleys........................................... 87 General Procedure: Installing the Lift Pulley ................................................... 88 General Procedure: Observing Your Lift Installation ....................................... 88

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Activity 2 – Positive Drives..................................................................................... 89 General Procedure: Observing Your Lift Installation ....................................... 89 General Procedure: Installing the Synchronous Pulleys................................... 89 General Procedure: Installing the Synchronous Belt ........................................ 90 General Procedure: Observing Your Lift Installation ....................................... 90 General Procedure: Changing the Gears ........................................................... 90 General Procedure: Observing the Change in Speed ........................................ 91 General Procedure: Removing the Synchronous Pulleys and Belt ................... 92 General Procedure: Installing the Chain Pulleys.............................................. 92 General Procedure: Aligning the Chain Pulleys................................................ 92 General Procedure: Installing the Chain ........................................................... 93 General Procedure: Running the Trainer .......................................................... 93

Topic 10 – Pulleys ..................................................................................................... 95 Activity 1 – Fixed Pulleys ....................................................................................... 97 Activity 2 – Movable Pulleys................................................................................... 98

Appendices................................................................................................................. 99 Appendix A – Operating Safety ............................................................................ A-1 Appendix B – Internet Resources ......................................................................... B-1

Mechanical Systems Introduction

1

INTRODUCTION

This CELL Guide is to be used with the multimedia presentation and Student Guide/Portfolio. The CELL Guide remains at the workstation and contains information and procedures that are specific to the CELL. This CELL Guide includes topic information, hands-on instructions, and appendices specific to the CELL. The information in the CELL guide follows the arrangement below:

♦ topic objective ♦ topic overview ♦ new terms and words ♦ activity objectives ♦ procedures for completing activity tasks

Appendices include Safety, Internet Resources, or other CELL specific tables or charts. Tips for navigating the multimedia presentation are detailed in the Tech-Lab Multimedia User’s Guide. There should be a copy of this at the student workstation. If this is not available, please ask your instructor.

Mechanical Systems Introduction

2

Selecting Procedures to Perform 1. This Mechanical Systems, Level 1 CELL Guide has three types of Procedures:

• General Procedures • Hardware Procedures • Software Procedures.

2. You must follow two of the three types of procedures in this CELL Guide. Skip

the type of procedure that does not apply to your equipment. 3. If you are working with the actual Hydraulics Training System and actual

hydraulic and electrical equipment (hardware) you must perform the General Procedures and Hardware Procedures listed in this CELL Guide.

4. If you are working with the LabSim Hydraulics Equipment in the Lab-Volt

Virtual Laboratory (LVVL) (software) you must perform the General Procedures and Software Procedures listed in this CELL Guide.

Mechanical Systems Topic 1 – Introduction to Mechanical Systems

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TOPIC 1 – INTRODUCTION TO MECHANICAL SYSTEMS

Objective When you have completed this topic, you will be able to identify career opportunities in the mechanical systems field to help you plan a career. You will understand some fundamentals, history, and basic principles of mechanical devices.

Overview This topic includes activities to prepare you for future employment. For example, you will be able to list your knowledge and skills. By comparing your interests and abilities with those of professionals in mechanical careers, you can decide if you like the job responsibilities in one or more areas of the field. When a job interviewer asks for your achievements, you will be ready to provide a list of activities you accomplished in the Mechanical Systems CELL. A brief analysis of the fundamentals and the more important advancements in the field will help you get a feel for today’s level of technology. A look ahead at the remaining topics in this CELL will give you an idea of how you will be preparing for the transition from school to the workplace.

New Terms and Words actuators – mechanical devices that move or control something. conveyors – machines that carry or transport materials, such as a platform with belts, rollers, or hooks, used to move objects. hydraulics – a branch of science that deals with the practical applications of liquid in motion. pneumatics – a branch of science that deals with the practical applications of gases in motion. HVAC – heating, ventilation, and air conditioning. prime movers – power sources (a motor or engine) that convert fuel energy into force. Power from a prime mover passes through a machine, creating work. functional mechanisms – working machines. Fuel energy moves from the engine (the prime mover) through the drivetrain (the functional mechanism) to move the car's weight over a distance. fluid power – the use of fluids within machines to transfer force. verniers – small scales made to slide along a graduated instrument for indicating parts of divisions.


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Activity 1 – Mechanical Systems Basics

Objective When you have completed this activity, you will have the knowledge and skills to describe the history of mechanical devices and the advantages of machinery. You will be able to: • identify early machines. • examine how science improves machinery. • discuss why people created machines.


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Activity 2 – Work Experiences

Objective When you have completed this activity, you will have the knowledge and skills to begin investigating a career in mechanical technology. You will be able to: • identify career opportunities in mechanical technology. • prepare information for a job application form. • identify two reasons why machines were created. • describe the general content of the four sections of this CELL.


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Activity 3 – Make Your Future

Objective When you have completed this activity, you will have the knowledge and skills to describe the duties and responsibilities of several mechanical trades and professions. You will be able to: • identify career opportunities. • list duties within occupations.

Mechanical Systems Topic 2 – The Parts of a Hydraulic Circuit

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TOPIC 2 – THE PARTS OF A HYDRAULIC CIRCUIT

Objective When you have completed this topic, you will be able to identify parts of the Hydraulics I Training System. You will identify the symbols for these parts on a schematic diagram. You will perform maintenance procedures on the Power Unit.

Overview In this topic, you will learn to recognize the symbols on the trainer. You will read a schematic diagram to choose and install the correct parts. You will assemble a working machine that incorporates one or more hydraulic circuits.

New Terms and Words symbols – things that stand for or suggest something else. circuits – a complete path for hydraulic fluid starting and returning to the same point.


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Activity 1 – Diagram Reading

Objective When you have completed this activity, you will have the knowledge and skills to identify parts of a hydraulic diagram. You will be able to: • identify and name hydraulic symbols. • locate hydraulic symbols on a diagram.


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Activity 2 – Trainer Components

Objective When you have completed this activity, you will have the knowledge and skills to identify parts of the hydraulic trainer. You will be able to: • match hydraulic symbols with trainer parts. • identify trainer parts using hydraulic symbols and names.


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Activity 3 – Trainer Introduction

Objective When you have completed this activity, you will have the knowledge and skills to maintain the hydraulic trainer Power Unit. You will be able to: • prepare the Power Unit. • examine components. • list the steps to change hydraulic fluid. • explain how to change the filter.

Hardware Procedure: General Inspection 1. Move the Power Unit near the computer and look carefully at each part. Report

loose or broken parts to the instructor.

2. Make sure the electrical cord does not show any loose wires or damage. 3. Clean any dirt from the outside of the machine, since it may get into the fluid. 4. Wash excess fluid from the outside surface. Once you've completed the procedure, click on the Forward arrow to resume the multimedia presentation.

Mechanical Systems Topic 3 –Assemble and Operate a Circuit

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TOPIC 3 – ASSEMBLE AND OPERATE A CIRCUIT

Objective When you have completed this topic, you will be familiar with the components, safe operation, and maintenance of the Power Unit.

Overview You will perform maintenance procedures on the Power Unit. You will read and interpret pictorial diagrams and assemble and safely operate the Power Unit. The knowledge and skills you learn in this topic can be applied to machines you use every day.

New Terms and Words kinks – creases or folds. pressure drop – a difference of pressure from one point in a circuit to another.


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Activity 1 – Operating Safety

Objective When you have completed this activity, you will have the knowledge and skills to perform proper safety procedures when using hydraulic equipment. You will be able to: • inspect trainer components. • specify the bending limit of a hydraulic hose. • describe and use safety procedures.

Hardware Procedure: Specifying the Bending Limit of a Hydraulic Hose An experienced technician will know just how far to bend a flexible connecting hose. To gain this experience, perform the following steps: 1. Take the 3-foot (91.44 cm) connecting hose and place it on the trainer tray.

2. Place a ruler on the tray.

3. Lift the hose.

4. While holding the hose over the ruler, bend it into a semicircle 6 inches in

diameter. The minimum bend diameter of the hose is 6 inches (152.4 mm). If you force the ends of the semicircle closer together than 6 inches (152.4 mm), the hose may tear.

Hardware Procedure: Testing the Connection Fittings The connection fittings should be in working condition. To test this, do the following: 1. Move each ball inside the fitting with your finger. 2. If any ball sticks, clean the ball lock and apply fresh oil. (Stuck ball locks will

prevent proper connections.) 3. Check that the knurled ring moves freely. 4. If the ring is too difficult to move, get a new hose.


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Hardware Procedure: Safety Precautions Always perform the following safety procedures before you start the Power Unit.

• Know and use all safety precautions. • Wear approved eye protection, cloth-lined rubber gloves, and protective

clothing. • Clear the area of hazards. • Prevent others from coming too close to the unit. • Report any dangerous conditions to your instructor. • Do not use a damaged flexible connecting hose. • Give any damaged hoses to your instructor for replacement.

Hardware Procedure: When Running the Power Unit The following safety procedures protect you and others while you operate the Power Unit.

• Be sure you are wearing safety goggles and protective clothing. • If you notice a leak, turn the Power Unit off. • Move out of the way of leaks. • Handle fluid with cloth-lined rubber gloves. • If any fluid gets on your skin, wash it off immediately. • Keep cloth or paper towels nearby to wipe oil from the parts. • Keep a fire extinguisher nearby.

Hardware Procedure: Stopping the Power Unit To end an activity in which the Hydraulics I Training System is used, perform the following procedure: 1. Turn the Power Unit switch to the OFF position. 2. Drain fluid back into the reservoir for five minutes. Make sure there is no

pressure in any part of the system. Whenever possible, release all pressure through a drain valve into the reservoir.

3. Point the connector away from yourself and others while connecting or disconnecting a flexible connecting hose. Remove all flexible connecting hoses from the Power Unit.

WARNING: A connector that is difficult to remove may still be under pressure.


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Hardware Procedure: Removing and Inspecting Quick-Connect Hydraulic Hoses To remove the quick-connect fitting from the part fitting, perform the following. 1. Place a towel under the connection fitting. 2. Place one hand on the brass fitting. 3. Grasp the hose with the other hand. 4. Push the hose toward the connector (this loosens the ball lock). 5. Pull back on the sliding ring (this opens the ball lock). 6. Pull the hose away from the connection. 7. Drip excess oil into the drain pan or a towel. 8. Wipe oil from the exterior. After removing the quick-connect fittings at both ends of the connecting hose, perform the following. 1. Inspect the hose for cuts, breaks, splits, or bulges. 2. Report any equipment damage to your instructor. 3. Place the flexible connecting hoses into the storage rack. 4. Wipe any spilled oil from all surfaces. 5. Return the trainer to its storage location. Once you've completed the procedure, click on the Forward arrow to resume the multimedia presentation.


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Software Procedure: Software Overview The Hydraulics Equipment in the Lab-Volt Virtual Laboratory (LVVL) provides three-dimensional replicas of the work surface, Power Unit, hydraulic components, and electrical control components included in the actual Hydraulics Training System. These replicas can be installed and operated in the same way as the actual equipment, and can be interconnected with hoses and leads to build a great variety of hydraulic circuits. Thus, you can perform many of the same demonstrations and exercises which are performed on the actual Hydraulics Training System.

Software Procedure: Tool Functions

Select tool

This is the most-often used tool. It allows selection of an object in the virtual laboratory. To select an object place the mouse pointer on the object and left-click. You cannot drag an object without first selecting this tool from the tool bar. Pan tool

The Pan tool lets you scroll across the virtual laboratory in any direction by dragging the pointer. The view changes according to the direction that you scroll the mouse pointer. Move Tool As the name implies, the Move tool permits you to move either forward or backward in the virtual laboratory. Forward motion is performed by moving the mouse pointer upward while holding the mouse left button. Backward motion is performed by moving the mouse pointer downward while holding the mouse left button. Camera Tool This tool allows you to observe the virtual laboratory from any angle. Note that the mouse pointer changes to a helicopter it is selected.


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Zoom Tool With the Zoom tool, you can zoom in or zoom out. Moving the mouse pointer upward while holding the mouse left button magnifies the view. Moving the mouse pointer downward while holding the left button zooms out. Zoom Window The Zoom Window tool zooms in on a particular area. This is performed by depressing the mouse left button while dragging the pointer to define a rectangular area. The defined area becomes a window that shows a magnified view.

Software Procedure: Equipment Views Various equipment views are available for most components in the virtual laboratory. Equipment views can be accessed by right-clicking on a selected object. A pop-up menu offers the options of Close-up View, Cutaway View, or Meter View depending on the piece of equipment. Close-up View This option provides an enlarged view of the object that is currently selected. For example, when a training module is selected, the close-up view makes it easier to read inscriptions on the front panel of the module.

Close-up View: Directional Valve Cutaway View View that shows what is inside the selected hydraulic component. For example, when an object is selected, the cutaway view shows the parts inside the component as well as oil flow (if any).

Cutaway View: Directional Valve


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Meter View View which displays the selected meter. For example, when a Flowmeter is selected, the meter view shows an enlarged version of the gauge. This feature makes it easier to read values indicated by the meter.

Meter View: Flowmeter

Software Procedure: Equipment Installation Select the piece of equipment to be installed by clicking the corresponding button on the Hydraulics equipment bar or by choosing the corresponding command in the LVVL Equipment menu. The Lab-Volt Virtual Laboratory is not limited to virtual hydraulic systems. Several training systems are available. If your software contains multiple training systems, you must select View>Equipment Bar>Hydraulics or Equipment>Hydraulics from the program’s top menu bar to install hydraulic components.

Once selected, the component to be installed is displayed beside the mouse pointer and is transparent. Drag the transparent part to the location where you wish to install it. Click the left mouse button to install the piece of equipment. Once installed, the component is no longer transparent.


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Activity 2 – Component Installation

Objective When you have completed this activity, you will have the knowledge and skills to install hydraulic components according to a pictorial diagram. You will be able to: • read and interpret a pictorial diagram. • attach a flexible connecting hose to the Power Unit, creating a complete

hydraulic system circuit.

Hardware Procedure: Flexible Hose Connection To connect the three-foot-long (91.44 cm) hose, do the following: 1. Hold the hose near the fitting at one end. 2. Using your other hand, pull the knurled ring on the metal connector toward the

hose. This releases the ball lock. 3. Slide the connector end over the T-port fitting and push hard. 4. Release the ring. It should click as it locks into place. 5. Gently push and pull on the connector to see if it is secure. 6. If the hose end comes off the fitting, repeat the procedure until the hose remains

connected to the T-port on the Power Unit. 7. Connect the other end of the flexible connecting hose to the P-port on the Power

Unit. Practice this procedure until you can make secure connections.


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Hardware Procedure: Ending the Activity To end this activity: 1. Remove the flexible connecting hose and place it into the hose storage rack. 2. Clean spilled oil from all surfaces. 3. Return the Power Unit to its storage location. Once you've completed the procedure, click on the Forward arrow to resume the multimedia presentation.

Software Procedure: Flexible Hose Connection 1. Open LVVL Virtual Lab for LVSim

(LVSIM_HYD version). 2. Select File>New and then save the new

file as Flex Hose with your initials. (For example: Flex Hose GP)

3. Create a work surface by clicking on its

icon . Drag the table into a desired position within the virtual lab.

NOTE: You can change your view of the trainer with the Camera tool . Use it to tilt and/or rotate the perspective.

4. Create a Power Unit (6310) by clicking

its icon . Drag the unit close to the work surface.

5. If the Power Unit is on, use the Select

tool and click on the On/Off switch to flip it to the Off position.

NOTE: You can use Zoom tool to enlarge or reduce the view.


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NOTE: Clicking on a port with the Select tool connects a hose to that port. To connect the other end of the hose you can drag to or click on another port.

6. Connect a hose between the Return (T) and Pressure (P) ports of the Power Unit. 7. Click on the On/Off switch to flip it to the On position. 8. Right-click on the Power Unit and

select Cutaway View from the pop-up menu.

NOTE: Cutaway View animates the internal operation of the selected component.

9. Turn the Power Unit switch to Off

and observe the Cutaway View.

NOTE: To remove a quick-connect hydraulic hose from one connection, click on the fitting with the Select tool and drag the hose off. To completely remove a hose from the circuit, click on the hose with the Select tool and press the Delete key.


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10. Click on the hose to select it and press the Delete key.

11. Click on the On/Off switch to flip it to On and observe the operation of the

Cutaway View.

12. Turn the Power Unit Off. 13. Save your project. 14. Close LVVL Virtual Lab for LVSim and return to the multimedia presentation,

Acomplishments.


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Software Procedure: Making Electrical Equipment Connections Making lab setups often involves electrical connections between the various pieces of equipment installed in the Lab-Volt Virtual Laboratory (LVVL). This section provides instructions for the installation and connection of electrical components as you create a simple electrical circuit.

1. Open LVVL Virtual Lab for LVSim (LVSIM_HYD version). 2. Select File>New and then save the new file as E-Circuit with your initials. (For

example: E-Circuit GP) 3. Create a work surface by clicking on its icon . Drag the table into a desired

position within the virtual lab.

NOTE: You can use the Camera tool to tilt and/or rotate the perspective.

4. Create a 24-volt DC power supply (6360) by clicking its icon. Drag the unit close to the left side of the work surface.

5. With the Select tool active, right-click on

the power supply and choose Rotate from the pop-up menu. (The mouse pointer becomes a circular arrow.)

6. Hold down the left mouse button and

rotate the power supply clockwise until the Lab-Volt logo is close to the left side of the workbench.


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7. Create another 24-volt DC power supply (6360) by clicking its icon. Drag the unit close to the middle-front of the work surface.

8. Create a Pushbutton Station (6361) by clicking its icon. Drag the unit near the center of the work surface.

9. Create a Pilot-Lamp Station (6365) by clicking its icon. Drag the unit near the middle-back of the work surface.

10. Create a Relay (6363) by clicking its icon. Drag the unit near the back of the work surface.

NOTE: Making electrical connections is similar to the procedure for making hydraulic connections. Place the mouse pointer over a terminal or a connector and click the left mouse button to connect one end of a lead or a cable to this terminal or connector. Place the mouse pointer over another terminal or connector that is similar to that selected previously and click the left mouse button to complete the connection.


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11. Connect the black and red terminals from the left power supply to one set of red and black terminals on the pushbutton switch.

12. Connect the other set of black and red terminals from the pushbutton switch to

the black and red terminals (#10 and #11) of the relay coil on the relay.

13. Connect the red and black terminals of the front power supply to the red and

white relay terminals #8 and #9. 14. Connect terminals #3 and #4 of the Pilot Lamp to terminals #9 and #7 of the

relay.

NOTE: The next step applies voltage to one side of the Pushbutton switch.


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15. If the left power supply is not already on, turn (click on) the On/Off switch to the On position. (A glowing red switch indicates the unit is on.)

16. If the front power supply is not on, turn (click on) the On/Off switch to turn it on.

NOTE: The next step verifies that you have constructed an operational electrical circuit.

17. Press (click on) the black button of the Pushbutton switch and observe the

orange pilot light. As the black pushbutton is depressed, the orange pilot light should illuminate.

18. If the circuit functioned correctly proceed to the next step. If the circuit did not

function correctly, review this procedure and recheck all of your connections for accuracy.

19. Save your E-Circuit XX file. (The XX represents your initials.) 20. Close the Virtual Lab for LVSim program. Once you've completed the procedure, click on the Forward arrow to resume the multimedia presentation.


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Activity 3 – System Operation

Objective When you have completed this activity, you will have the knowledge and skills to operate and test a hydraulic Power Unit. You will be able to: • run the Power Unit. • read the gauge to check the drop in pressure across the filter. • check the fluid level after a temperature change. • explain how a change in temperature affects the volume and flow rate of

hydraulic fluid.

Hardware Procedure: Preparing the Power Unit You will now prepare the Power Unit for operation. Before starting the Power Unit, check the: • pressure by reading the gauge above the oil filter. • oil gauge on the reservoir to make sure that clean oil reaches the black line. • tightness of the filter.

Hardware Procedure: Preparing for Safe Operation You and your partner will now prepare yourselves and others for safe operation. • Read and understand all the safety procedures before starting the unit. • Wear approved eye protection, cloth-lined rubber gloves, and protective clothing. • Clear the area of hazards. • Prevent others from coming too close to the unit.


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Hardware Procedure: Power Unit Operation This activity includes taking readings of oil level, pressure, and temperature. You will compare readings taken before and during the operation of the Power Unit. To begin this procedure: 1. Install a 3-foot-long (91.44 cm) flexible connecting hose between the P (pump)

and T (tank) ports of the Power Unit. 2. Place a piece of masking tape next to the oil level indicator. 3. Mark the oil level on the masking tape. 4. Plug the Power Unit power cord into a three-prong wall receptacle (15-ampere,

120-volt alternating current.)

Power Unit Operation Table OIL LEVEL TEMPERATURE PRESSURE

(psig/bar)) BEFORE STARTING ONE-MINUTE RUN TIME TEN-MINUTE RUN TIME Before starting the unit, take readings and record them in the Power Unit Operation Table in your Student Guide/Portfolio. 5. Write the height of the oil in the BEFORE STARTING row in the table. Use a

ruler to measure from the bottom of the oil level indicator to the mark on the masking tape.

6. Record the temperature reading in the BEFORE STARTING row in the table. 7. Look at the Pressure Gauge and record the reading in the table. 8. Move the Power Unit switch to the ON position. 9. If oil spills, move the Power Unit switch to the OFF position, then disconnect the

power cord from the wall receptacle. 10. Let the Power Unit run for one minute, then check the oil level.


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11. Write the height of the oil in the ONE-MINUTE RUN TIME row in the table. 12. Record the temperature reading in the ONE-MINUTE RUN TIME row in the

table. 13. Look at the Pressure Gauge and record the reading in the table. 14. Let the Power Unit run for ten minutes, then check the oil level. 15. Write the height of the oil in the TEN-MINUTE RUN TIME row in the table. 16. Record the temperature reading in the TEN-MINUTE RUN TIME row in the

table. 17. Look at the Pressure Gauge and record the reading in the table. 18. Move the power switch to the OFF position.

Hardware Procedure: Ending the Activity Follow this procedure to complete the activity: 1. Disconnect the flexible connecting hose. 2. Wipe excess oil from the connectors. 3. Place the hose into the hose storage rack. 4. Clean spilled oil from all surfaces. 5. Return the Power Unit to its storage location. Once you've completed the procedure, click on the Forward arrow to resume the multimedia presentation.

Mechanical Systems Topic 4 –Fundamental Concepts

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TOPIC 4 – FUNDAMENTAL CONCEPTS

Objective When you have completed this topic, you will understand the concepts of water pressure and flow rate. You will be able to relate them to the force of gravity and pump power. You will also be able to read pump performance graphs and use your knowledge to select the proper pump to suit a specific application.

Overview To have knowledge of hydraulics, you must have an understanding of pressure, what causes pressure, and how pressure can be used to make our lives easier. In the first activity of this topic, you will use a static pressure simulator to measure and record the weight of water and also record water pressure at different height intervals. You will use this information to calculate pressures in a deep-sea environment. In the second activity, you will use a pump head simulator to record pump flow rates at 1-foot height intervals, describe pump head pressure ratings, and read a pump curve to determine pump performance specifications.

New Terms and Words Archimedes' principle – an object floating upon a fluid is pushed upward by a force equal to the weight of the displaced fluid. This floating force is called buoyancy. force – a vector quantity that tends to produce an acceleration of a body in a specified direction. Note: This is a formal definition. impeller – the spinning part of a pump that has curved, paddle-like portions (vanes) used to push the fluid through the pump body. troubleshooting – locating and correcting causes of problems in machinery and technical equipment.


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Activity 1 – Static Pressure

Objective When you have completed this activity, you will have the knowledge and skills to calculate and measure the static pressure of water. You will be able to: • measure and record the pressure of water at 1-foot (0.305 m) height intervals. • define static pressure. • use United States Customary and International System (SI) unit conversions. • calculate static water pressure. • compare observed and calculated static water pressures.

Hardware Procedure: Static Pressure Simulator 1. Click on the red slider at the bottom of the water column and move it to the 1-ft

(0.305 m) mark on the column. (The blue area represents water rising in the column.)

2. Observe the reading of static pressure on the gauges to the right of the column.

Record the reading on a piece of paper. 3. Move the red slider to the 2-ft (0.61 m) mark on the column. 4. Observe the reading of static pressure on the gauges to the right of the column.

Record the reading on the same piece of paper. 5. Move the red slider to the 3-ft (0.915 m) mark on the column. 6. Observe the reading of static pressure on the gauges to the right of the column.

Again, record the reading on the same piece of paper. 7. Close the Static Pressure Simulator by clicking on Quit at the bottom right of

the simulator window or clicking on the X in the top right of the window. Once you've completed the procedure, click on the Forward arrow to resume the multimedia presentation.


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Activity 2 – Pump Head

Objective When you have completed this activity, you will have the knowledge and skills to measure pump head pressure. You will be able to: • measure and record pump flow rates at 1-foot (0.305 m) height intervals. • determine pump performance ratings. • plot and interpolate points on a graph. • read a pump curve to determine pump performance specifications. • compare the function and purpose of a pump in a hydraulic circuit with a pump

performance graph.


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Hardware Procedure: Pump Head Simulator 1. Click on the red slider at the bottom of the water column and move it to the 1-ft

(0.305 m) mark on the column. 2. Click on the Set button. (If you make a mistake at any time, press the Reset

button; the red dots will be cleared from the graph and the water in the column will return to the 0-ft (0 m) mark.)

3. Locate the red dot, then find the gpm (at the bottom of the graph) for that height

of water. You will have to approximate the gpm value as best as you can. 4. Enter the gpm value in the first row under the gpm column in the table in your

Student Guide/Portfolio. 5. Repeat this procedure for each height on the water column (up to and including

8 feet). 6. Complete the rest of the table in your Student Guide/Portfolio. 7. If you have access to a printer, print this screen by clicking on Click here to print

screen at the bottom left of the simulator window. If not, you can find a printed copy of this screen in your Student Guide/Portfolio.

8. Close the Pump Head Simulator by clicking on Quit at the bottom right of the

window or clicking on the X in the top right of the window. Once you've completed the procedure, click on the Forward arrow to resume the multimedia presentation.

Mechanical Systems Topic 5 – Test a Circuit

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TOPIC 5 – TEST A CIRCUIT

Objective When you have completed this topic, you will be able to measure the hydraulic fluid flow rate, identify and join movable components, measure friction in actuators, and estimate the weight of a load.

Overview You will install components by following a connection diagram. You will follow safety procedures to protect yourself and others in the classroom. You will report changes in the temperatures, pressures, and flow rates of hydraulic fluid. You will also study the efficiency of the actuator, calculate friction, and estimate the weight of a load.

New Terms and Words orifice – a precisely designed hole. It permits a specific amount of fluid to pass through at a given pressure; therefore, it is sometimes called a metering device.

Power Unit Maintenance Power unit maintenance includes:

• cleaning the unit. Wash it with mild soap and water. Strong or abrasive cleansers will damage plastic parts and painted surfaces.

• adding or replacing of hydraulic fluid as needed. • testing its operation. • setting the pressure relief value.

Preparation Power unit preparation includes:

• placing a drain pan that will hold 5 U.S. gallons (20 liters) under the reservoir drain.

• placing a fluid diverter (a curved piece of metal) under the drain fitting to channel oil away from the wheeled platform into the pan.


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Quick-Connect Inspection • Wipe the hose clean. • Remove the quick-connect fitting by pushing the hose toward the connector. • Pull back on the sliding ring. The locking ring should move smoothly. • Pull the hose away from the connection. • Drip excess oil into the drain pan or a towel. • Wipe the connection fitting clean and inspect the quick-connect fitting. • Inspect the hose for cuts, breaks, splits, or bulges. • Replace damaged hoses. • Wash oil from the exterior.


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Hydraulic Fluid Inspection It is extremely important to use clean hydraulic fluid at all times. Dirt in the fluid will act like sandpaper on seals and shafts. Fluid will escape from worn seals. Worn shafts will move out of alignment, creating further seal damage. When you are inspecting the fluid, look for metal and other particles; these damage hydraulic parts. They are evidence of mechanical breakage. Very small particles pass though the filter. Clean-looking oil may still be abrasive. Check with your instructor if you notice any particles in the hydraulic fluid.


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Activity 1 – System Measuring

Objective When you have completed this activity, you will have the knowledge and skills to measure the hydraulic fluid flow rate. You will be able to: • install components including Pressure Gauges and a Flowmeter by following a

connection diagram. • read Flowmeters. • connect and adjust a Flow Control Valve. • record set point pressures.


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Hardware Procedure: Install the Components by Following a Connection Diagram

1. Snap a 6390 5-port Manifold onto the lower left corner of the trainer tray. 2. Snap another 5-port Manifold onto the center left edge of the tray. 3. Install a 6350 Pressure Gauge a short distance (3 to 6 inches or 7.62 to 15.24 cm)

to the right of the top fitting on each of the 5-port Manifolds. 4. Install the 6351 Flowmeter to the right of the lower Pressure Gauge. Turn the

Flowmeter until you can read upright lettering on the glass. 5. Install a long flexible connector from the pressure (P) port to the center

horizontal fitting on the 5-port supply Manifold nearest to you. 6. Install a long flexible connector from the tank (T) port to the center horizontal

fitting on the more distant 5-port return Manifold.


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7. Install a short flexible connector from the end port on the return Manifold to a fitting on its nearest gauge.

8. Install a short flexible connector from the end port on the supply Manifold to a

fitting on its nearest gauge. 9. Install a short flexible connector from the end port on the return Manifold to the

most distant outlet (OUT) fitting on the Flowmeter. 10. Install a short flexible connector from the end port on the nearest Manifold to

the bottom inlet (IN) fitting on the Flowmeter. 11. Inspect the Hydraulic I Training System to make sure it is safe. 12. Clear the area of objects and people not involved with the trainer. 13. Plug the power unit cord into an AC power receptacle. 14. While looking for a fluid leak, flip the switch to the ON position. If you see a

leak, switch the power unit OFF, then call your instructor. If the operation is safe, let the machine run.

15. In this setup, without a flow control valve, the pressure gauges show no

significant pressure readings. Record the liter-per-minute (L/min) flow rate in the first row of the Pressure and Flow data sheet in your Student Guide/Portfolio.

16. Turn the power unit switch to the OFF position. Unplug the cord to prevent

someone from restarting the machine while you proceed with the next task. Click on the Forward arrow to resume the multimedia presentation.

WARNING: The Hydraulics I Training System creates high fluid pressure. A stream of hydraulic fluid leaking from it can cause severe injury. Also, be aware that you are dealing with a potentially harmful current.


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Hardware Procedure: Installing a Flow Control Valve 1. Snap the Flow Control Valve onto the tray between the supply Manifold (the 5-

port Manifold connected to the port marked P on the Power Unit) and the Flowmeter.

2. Remove the hose from the Flowmeter inlet connector and connect it to the Flow

Control Valve inlet (IN). 3. Install a short connector between the Flow Control Valve outlet (OUT) and the

Flowmeter inlet fitting. 4. Turn the flow control knob counterclockwise until it stops. This is the fully open

position. 5. Plug the power cord into an AC power outlet. 6. Move the power switch to the ON position. Hydraulic fluid should flow through

the flowmeter at more than 3 L/min. The pressure gauge should indicate less than 100 psig (6.9 bar). If the pressure gauge is over 500 psig (34.5 bar), turn the flow control valve counterclockwise until the gauge pressure drops below 100 psig (6.9 bar).

Hardware Procedure: Recording the Pressure and Flow When the flow control knob is turned counterclockwise all the way, record the supply pressure and flow rate on the Pressure and Flow data sheet in your Student Guide/Portfolio. 1. Turn the flow control knob until the pressure rises to 600 psig (41.37 bar). Record

your readings on the data sheet. 2. Adjust the Flow Control Valve until the pressure is 200 psig (13.79 bar). Prepare to record your readings on a new line of the Pressure and Flow data sheet at each setting during this procedure. 3. Turn the flow control knob to adjust the pressure from 200 psig (13.79 bar)

upward in steps of 20 psig (1.379 bar) until the flow reaches 1 L/min. 4. At each 20 psig (1.379 bar) setting, record your observations in the Comment

column regarding changes in noise and ease of setting the pressure.


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Hardware Procedure: Cleanup 1. Move the Power Unit switch to the OFF position. 2. Remove the power plug from the wall receptacle and wrap the cord around the

rear cord holder. 3. While holding rags or absorbent paper towels under the fittings, remove all parts

and return them to their storage locations. 4. Clean the area of oil and dirt. 5. Place the Hydraulics I Training System in its storage location. Once you've completed the procedure, click on the Forward arrow to resume the multimedia presentation.


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Software Procedure: Install the Components by Following a Connection Diagram Refer to the connections diagram and installation steps.


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1. Open LVVL Virtual Lab for LVSim (LVSIM_HYD version). 2. Select File>New and then save the new file as Flow Control with your initials.

(For example: Flow Control GP) 3. Install a Work Surface (6301) by clicking on its icon . Drag the table into a

desired position within the virtual lab.

4. Install a Power Unit (6310) by clicking its icon . Drag the unit close to the work surface.

5. If the Power Unit is on, use the Select tool and click on the On/Off switch to

flip it to the Off position. 6. Install a 5-port Manifold (6390) onto the lower left corner of the trainer tray. 7. Install another 5-port Manifold (6390) onto the center left edge of the tray. 8. Install two Pressure Gauges (6350) at a short distance to the right of the top

fitting on each of the 5-port Manifolds. 9. Install a Flowmeter (6351) to the right of the lower Pressure Gauge.


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10. Install a hose from the pressure (P) port of the Power Unit to the center

horizontal fitting on the 5-port supply Manifold nearest to you. 11. Install a hose from the tank (T) port of the Power Unit to the center horizontal

fitting on the more distant 5-port return Manifold. 12. Install a hose from the end port on the return Manifold (see diagram) to a fitting

on its nearest gauge. 13. Install a hose from the end port on the supply Manifold to a fitting on its nearest

gauge. 14. Install a hose from the end port on the return Manifold to the outlet (OUT)

fitting on the Flowmeter. 15. Install a hose from the end port on the nearest Manifold to the bottom inlet (IN)

fitting on the Flowmeter. 16. Turn (click) on the Power Unit switch if it is not already on. 17. Right-click on the lower (supply line) Pressure Gauge and select Meter View

from the pop-up menu. 18. Check that the pressure reads approximately 50 psi (3.45 bar). If it does not,

review this procedure and check your connections for accuracy. 19. Right-click on the Flowmeter and select Meter View from the pop-up menu.


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20. Check that the meter reads above 3.0 LPM. If it does not, review this procedure and check your connections for accuracy.

21. Save your Flow Control XX file. (The XX represents your initials.)


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Software Procedure: Installing a Flow Control Valve 1. Open your Flow Control XX file if it is not already open. 2. Turn off the Power Unit if it is on. 3. Install the Flow Control Valve (6321) between the supply Manifold (the Manifold

connected to the P port of the Power Unit) and the Flowmeter. 4. Remove the hose from the Flowmeter inlet connector and connect it to the Flow

Control Valve inlet (IN). 5. Install a hose between the Flow Control Valve outlet (OUT) and the Flowmeter

inlet fitting.

NOTE: In the next two steps you will adjust the Flow Control Valve from no flow (0% setting) to full flow (100% setting.) Observe the actions of the Flowmeter and Pressure Gauge as you adjust the flow.


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6. Turn on the Power Unit. 7. Click on the Flow Control Valve to view the setting knob. 8. Drag the flow control knob counterclockwise with the mouse

pointer for a 100% setting. This is the fully open position. You can also use the up and down arrows to change the flow setting to 100%.

Software Procedure: Recording the Pressure and Flow 1. When the flow control knob is set to 100%, record the supply pressure and flow

rate on the Software Procedure: Pressure and Flow data sheet in your Student Guide/Portfolio.

2. Turn the flow control knob until the pressure rises to 600 psig (41.37 bar).

Record your readings on the data sheet. 3. Adjust the Flow Control Valve until the pressure is 200 psig (13.79 bar). 4. Prepare to record your readings on a new line of the Software Procedure:

Pressure and Flow data sheet at each setting during this procedure. 5. Turn the flow control knob to adjust the pressure from 200 psig (13.79 bar)

upward in steps of 20 psig (1.379 bar) until the flow reaches 1 L/min. 6. At each 20 psig (1.379 bar) setting, record your observations in the Comment

column regarding the ease of setting and reading the pressure. 7. Save your file. 8. Close the LVVL Virtual Lab LabSim program. Once you've completed the procedure, click on the Forward arrow to resume the multimedia presentation.


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Activity 2 – Efficiency

Objective When you have completed this activity, you will have the knowledge and skills to measure friction in actuators. You will be able to: • read a connection diagram. • assemble an actuator circuit, including a Flow Control Valve. • actuate connected components. • vary resistance to fluid flow and regulate pressure in the circuit. • measure pressure drops across system components. • read gauge pressures in various hydraulic circuit locations. • observe and record changes in flow and pressure. • calculate load weight and friction.


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Hardware Procedure: Preparing the Trainer To prepare a circuit to lift the Power Unit, perform the following steps:

1. Install the actuator on the Power Unit frame and connect the actuator to the Power Unit.

2. Place the components on the tray according to the connection diagram and

connect the hoses. 3. Prepare the Power Unit by adding oil to the correct level. 4. Clear the area of objects and people not involved with the trainer. 5. Make sure the hoses and the Power Unit cord will not become wedged between

rigid parts of the trainer when the Power Unit moves. 6. Plug the Power Unit cord into a 115-volt receptacle


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Hardware Procedure: Running the Power Unit

WARNING: The Hydraulics I Training System creates high fluid pressure. A stream of hydraulic fluid leaking from it can cause severe injury. Also, be aware that you are dealing with a potentially harmful electric current.

1. While looking for a fluid leak, switch the power on. 2. If you see a leak, turn the machine off immediately and call your instructor. 3. Once you are sure the machine is safe, run the Power Unit.

Hardware Procedure: Adjusting the Pressure Hydraulic fluid should flow through the Flowmeter at more than 3 liters per minute (L/min). If the Pressure Gauge is over 500 psig (34.5 bar), turn the Flow Control Valve counterclockwise until the gauge pressure drops below 100 psig (6.9 bar). 1. Lift the knob of the Flow Control Valve and turn it counterclockwise until it

stops. This is the lowest pressure position. 2. Write the supply pressure and flow rate you observe on the Pressure and Flow

data sheet in your Student Guide/Portfolio. For example:

psig Bar L/min Comment 30 2.07 3.5 fully open

3. Turn the knob of the Flow Control Valve clockwise until the pressure rises to

200 psig (13.79 bar). 4. Write your readings on the next line of the data sheet.

NOTE: If the Flow Control Valve does not regulate pressure at any position within its range, it means that the valve is not connected correctly. Turn the unit off. Move the Flow Control Valve inlet connection to the outlet and the outlet connection to the inlet, then restart the procedure.

5. Slowly turn the knob of the Flow Control Valve clockwise to adjust the pressure

upward in steps of 20 psig (1.379 bar) until you reach 400 psig (27.58 bar). 6. With each reading, record any changes in noise, actuator movement, flow, and

ease of setting the pressure.


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7. Repeat the process of raising and lowering the Power Unit. Observe and record the pressures at which the Power Unit rises and falls.

Hardware Procedure: Pressure and Flow Analysis Move the Power Unit switch to the OFF position. Review your entries on the data sheet. See if you can answer the following questions: 1. At which pressures did the Power Unit become louder? 2. Were any pressure settings difficult to set? 3. At what pressures did the Power Unit move? 4. Did the pressure sometimes change without moving the knob of the Flow Control

Valve? It would be good practice to run the procedure again to comment on these questions as you adjust the pressures. Once you've completed the procedure, click on the Forward arrow to resume the multimedia presentation.

Hardware Procedure: Computing Friction Loss 1. Record the pressure required to lift the Power Unit (Lift Pressure) on the

Friction Loss data sheet in your Student Guide/Portfolio. The information is from the Pressure and Flow data sheet.

2. Write the pressure reading at which the Power Unit started to drop (Drop

Pressure) in the Drop Pressure box. 3. Add the Drop Pressure and the Lift Pressure, then divide by 2. Write that

number in the Average Pressure box. 4. Subtract the Average Pressure from the Lift Pressure, then write the answer in

the Friction box.

Hardware Procedure: Cleanup 1. Move the Power Unit switch to the OFF position. 2. Remove the power plug from the wall receptacle and wrap the cord around the

rear cord holder. 3. While holding rags or absorbent paper towels under the fittings, remove all parts

and return them to their storage locations.


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4. Clean the area of oil and dirt. 5. Place the Hydraulics I Training System in its storage location. Once you've completed the procedure, click on the Forward arrow to resume the multimedia presentation.


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Software Procedure: Preparing the Trainer To prepare a circuit to lift the Power Unit, perform the following steps:

1. Open LVVL Virtual Lab for LVSim (LVSIM_HYD version).

2. Open your Flow Control XX file if it is not already open. 3. Select a Double-acting Cylinder (6341) by clicking the corresponding button on

the Hydraulics equipment bar. 4. Move the mouse pointer so that it is located on the lifting attachment of the

Power Unit. (The cylinder is shown in the upright position when the mouse pointer is located on the lifting attachment.)

5. Click the left mouse button to install the hydraulic cylinder on top of the lifting

frame of the Power Unit. 6. Connect hoses from the cylinder to the Manifolds as shown in the diagram. 7. Verify that the components on the work surface match the connection diagram. 8. Save your file as Flow Control Lift XX.


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Software Procedure: Adjusting the Pressure 1. Open LVVL Virtual Lab for LVSim (LVSIM_HYD version). 2. Open your Flow Control Lift XX file. 3. Turn the Power Unit on. 4. Lift the knob of the Flow Control Valve and turn it counterclockwise until it

stops. This is the lowest pressure position.

NOTE: Hydraulic fluid should flow through the Flowmeter at more than 3 liters per minute (LPM). If the Pressure Gauge is over 300 psig (20.68 bar), turn the Flow Control Valve counterclockwise until the gauge pressure drops below 100 psig (6.9 bar).

5. Write the supply pressure and flow rate you observe on the Pressure and Flow datasheet in your Student Guide/Portfolio. For example:

6. Turn the knob of the Flow Control Valve clockwise or adjust the setting

percentage until the pressure rises to 200 psig (13.79 bar). 7. Write your readings on the next line of the data sheet.

NOTE: If the Flow Control Valve does not regulate pressure at any position within its range, verify that the hoses are properly connected.

8. Slowly adjust the Flow Control Valve clockwise to increase the pressure in steps

of 20 psig (1.379 bar) until you reach 400 psig (27.58 bar). 9. With each reading, record any changes in noise, actuator movement, flow, and

ease of setting the pressure.

psig Bar LPM Setting % Comment 100 6.9 3.3 30 Power unit raises


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10. Repeat the process of raising and lowering the Power Unit. Observe and record the pressures at which the Power Unit rises and falls.

Software Procedure: Pressure and Flow Analysis Move the Power Unit switch to the OFF position. Review your entries on the data sheet. See if you can answer the following questions:

NOTE: If necessary, run the procedure again to comment on these questions as you adjust the pressures.

1. Were any pressure settings difficult to set? 2. Did the pressure sometimes change without moving the knob of the Flow Control

Valve?

Software Procedure: Computing Friction Loss 1. Record the pressure required to lift the Power Unit (Lift Pressure) on the

Friction Loss data sheet in your Student Guide/Portfolio. The information is from the Pressure and Flow data sheet.

2. Write the pressure reading at which the Power Unit started to drop (Drop

Pressure) in the Drop Pressure box. 3. Add the Drop Pressure and the Lift Pressure, then divide by two. Write that

number in the Average Pressure box. 4. Subtract the Average Pressure from the Lift Pressure, then write the answer in

the Friction box. 5. Save your file. 6. Close the LVVL Virtual Lab LabSim program. Once you've completed the procedure, click on the Forward arrow to resume the multimedia presentation.

Mechanical Systems Topic 6 – Circuit Control

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TOPIC 6 – CIRCUIT CONTROL

Objective When you have completed this topic, you will be able to assemble and operate meter-in and meter-out hydraulic circuits.

Overview In this topic, you will operate a meter-in hydraulic circuit, in which the fluid reaches the flow control before it reaches the actuator. You will also operate a meter-out hydraulic circuit, in which the fluid reaches the actuator before it reaches the flow control. By adjusting pressures and flow rates, you will observe and adjust the speed of the rod in the actuator. As a designer of a hydraulic machine, you would need to carefully consider where you place a hydraulic control. You can use the experience you've gained to learn some of the serious decisions an engineer must make to ensure the safety of hydraulic machinery operators.

New Terms and Words pressure differential – a difference in pressure from the supply line to the return line. For example, if the supply pressure is 180 psig and the return pressure is 80 psig, the pressure differential is 180 minus 80, or 100 psig.







Quick-Connect Inspection • Wipe the hose clean. • Remove the quick-connect fitting by pushing the hose toward the connector. • Pull back on the sliding ring. The locking ring should move smoothly.


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• Pull the hose away from the connection. • Drip excess oil into the drain pan or a towel. • Wipe the connection fitting clean and inspect the quick-connect fitting. • Inspect the hose for cuts, breaks, splits, or bulges. • Replace damaged hoses. • Wash oil from the exterior.

Hydraulic Fluid Inspection It is extremely important to use clean hydraulic fluid at all times. Dirt in the fluid will act like sandpaper on seals and shafts. Fluid will escape from worn seals. Worn shafts will move out of alignment, creating further seal damage. When you are inspecting the fluid, look for metal and other particles; these damage hydraulic parts. They are evidence of mechanical breakage. Very small particles pass though the filter. Clean-looking oil may still be abrasive. Check with your instructor if you notice any particles in the hydraulic fluid.


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Activity 1 – Meter-In Control

Objective When you have completed this activity, you will have the knowledge and skills to install and operate a hydraulic circuit in which the flow control is situated before the actuator. You will be able to: • assemble meter-in actuator circuits. • adjust the speed of actuation.


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Hardware Procedure: Preparing the Meter-In Circuit To control the flow rate in one direction, install the components on the Hydraulics I Training System tray as shown in the meter-in connection diagram on your screen. Attach flexible connectors between the parts.

To start the Power Unit, perform the following: 1. Wear eye protection, rubber gloves, and protective clothing. 2. Follow the safety procedures in the Operating Safety reference. 3. Switch the Power Unit to ON. If you see any fluid leaking, switch the Power

Unit to OFF and ask your instructor for help.

Hardware Procedure: Adjusting the Controls Adjust the flow control to deliver 1 liter per minute while watching the Flowmeter and moving the DCV to various positions.

Hardware Procedure: Moving the Actuator By adjusting the pressure and flow rate to specific numbers, you control the speed of the rod. Using a watch, clock, or stopwatch, or by counting slowly, count how many seconds it takes for the actuator rod to fully extend. Move the actuator rod out of the cylinder using the DCV handle. Move the actuator rod into the cylinder using the DCV handle. Count how many seconds it takes for the actuator rod to retract. Does the rod take as much time to go back into the cylinder as it does to extend?


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Hardware Procedure: Placing a Control Upstream

1. Stop the Power Unit. 2. To control the flow rate in both directions, install the Flow Control Valve on the

trainer tray between the pump and the directional control valve (DCV). Fluid from the pump will then flow through the regulator.

3. Start the Power Unit. Move the actuator rod in and out of the cylinder by

pushing and pulling the DCV handle. 4. Count how many seconds it takes for the actuator rod to retract. 5. Return the Hydraulics I Training System to its storage location. Clean the area. Once you've completed the procedure, click on the Forward arrow to resume the multimedia presentation.


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Software Procedure: Adjusting the Controls in a Meter-In Circuit To construct a meter-in circuit and control the flow rate in one direction refer to the following steps and use the following components.

ID # Part # Component Description Qty 1 & 2 6390 Manifold, 5 ports, fixed 2

3 6322 Relief Valve 1 4 6351 Flowmeter 1 5 6320 Directional Valve, Lever-operated 1 6 6321 Flow Control Valve, non-compensated 1 7 6350 Pressure Gauge 2 8 6340 Double-acting Cylinder, 2.5-cm Bore 1 6301 Work Surface 1 6310 Power Unit 1

Meter-In Circuit

1. Open LVVL Virtual Lab for LVSim (LVSIM_HYD version). 2. Select File>New and then save the new file as Meter-In with your initials. (For

example: Meter-In GP) 3. Install a work surface by clicking on its icon . Drag the table into a desired

position within the virtual lab. 4. Install the components on the LabSim work surface as shown in the meter-in

connection diagram. Attach flexible connectors (hoses) between the parts.


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5. Switch the Power Unit to ON. NOTE: A 30% flow control setting provides an approximate delivery of 1 to 2 liters per minute while the Directional Control Valve (DCV) is moved to various positions.

6. Adjust the Flow Control Valve to a setting of 30%.

NOTE: The DCV lever is moved by dragging it with the mouse. The control lever automatically returns to the center position when the left mouse button is released. However, the control lever remains in position (pushed or pulled) when the left mouse button is released while pressing the CTRL key. This feature allows you to set the control lever to any one of the three positions.

7. Click on the DCV handle and drag it one way and then the other way while observing the Flowmeter, Pressure Gauge, and piston movement.


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Software Procedure: Moving the Actuator

1. Adjust the pressure and flow rate to specific numbers to vary the speed of the

rod in the double-acting cylinder. 2. Move the actuator rod in and out of the cylinder using the DCV handle. 3. Adjust the flow rate so that the cylinder rod moves slowly. 4. Count how many seconds it takes for the actuator rod to fully extend. 5. Count how many seconds it takes for the actuator rod to retract.

NOTE: Does the rod take as much time to go back into the cylinder as it does to extend?

6. Save your file.


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Software Procedure: Placing a Control Upstream

1. Open LVVL Virtual Lab for LVSim (LVSIM_HYD version). 2. Open your Meter-In XX file. 3. Select File>Save As and then rename and save this file as Control Upstream

XX with your initials in place of the XX. (For example: Control Upstream GP)


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4. Delete the existing Flow Control Valve that connects the Directional Valve and the Pressure Gauge.

5. Connect a hose between the open port on the Directional Valve and the open port

on the Pressure Gauge. 6. Remove (delete) the hose connection between the Flowmeter and the Directional

Valve. 7. To control the flow rate in both directions, install a Flow Control Valve on the

work surface between the Flowmeter and the Directional Valve. (Fluid from the Power Unit pressure side will then flow through the Flow Control Valve.)

8. Connect hose between the open port on the Flowmeter and the Flow Control

Valve. 9. Connect another hose between the open port of the Directional Valve and the

open port of the Flow Control Valve.

10. Start the Power Unit. 11. Move the actuator rod in and out of the cylinder by pushing and pulling

(dragging) the Directional Valve handle. 12. Count how many seconds it takes for the actuator rod to retract. 13. Save your file.


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14. Close the LVVL Virtual Lab LabSim program. Once you've completed the procedure, click on the Forward arrow to resume the multimedia presentation.


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Activity 2 – Meter-Out Control

Objective When you have completed this activity, you will have the knowledge and skills to install and operate a hydraulic circuit in which the flow control is situated after the actuator. You will be able to: • assemble meter-out actuator circuits. • adjust the speed of actuation.


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Hardware Procedure: Preparing the Meter-Out Circuit

To control the flow rate in one direction, install the components on the Hydraulics I Training System tray as shown in the meter-out connection diagram on your screen. Attach flexible connectors between the parts. To start the Power Unit, perform the following: 1. Wear eye protection, rubber gloves, and protective clothing. 2. Follow the safety procedures in the Operating Safety reference. 3. Switch the Power Unit to ON. If you see any fluid leaking, turn the Power Unit

switch to OFF and ask your instructor for help.

Hardware Procedure: Adjusting the Controls 1. Adjust the pressure relief valve to create 200 psig (13.79 bar) in the circuit. To

check the pressure, move the DCV to its various positions while reading the gauge.

2. Adjust the flow control to deliver 1 liter per minute while watching the

Flowmeter and moving the DCV to various positions.


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Hardware Procedure: Moving the Actuator 1. By adjusting the pressure and flow rate to specific numbers, you control the

speed of the rod. 2. Using a watch, clock, or stopwatch, or by counting slowly, count how many

seconds it takes for the actuator rod to fully extend. Move the actuator rod out of the cylinder using the DCV handle.

3. Move the actuator rod into the cylinder using the DCV handle. Count how many

seconds it takes for the actuator rod to retract. Does the rod take as much time to go back into the cylinder as it does to extend?

Hardware Procedure: Placing a Control Downstream 1. Stop the Power Unit. To control the flow rate in both directions, install the Flow

Control Valve on the trainer tray between the DCV and the T (tank) port as shown on your screen. Fluid from the pump will then flow through the regulator at all times.

2. Start the Power Unit. Move the actuator rod in and out of the cylinder by

pushing and pulling the DCV handle. Count how many seconds it takes for the actuator rod to retract. Does it take as many seconds as it did before you moved the Flow Control Valve between the DCV and T port?

3. Return the Hydraulics I Training System to its storage location. Clean the area. Once you've completed the procedure, click on the Forward arrow to resume the multimedia presentation.


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Software Procedure: Preparing the Meter-Out Circuit

ID # Part # Component Description Qty 1 & 2 6390 Manifold, 5 ports, fixed 2

3 6322 Relief Valve 1 4 6351 Flowmeter 1 5 6320 Directional Valve, Lever-operated 1 6 6321 Flow Control Valve, non-compensated 1 7 6350 Pressure Gauge 2 8 6340 Double-acting Cylinder, 2.5-cm Bore 1 6301 Work Surface 1 6310 Power Unit 1

NOTE: A meter-out circuit controls flow rate in one direction.

1. Open LVVL Virtual Lab for LVSim (LVSIM_HYD version). 2. Open your Meter-In XX file. 3. Select File>Save As and then rename and save this file as Meter Out XX with

your initials in place of the XX. (For example: Meter Out GP) 4. Install the components on the work surface as shown in the meter-out

connection diagram. 5. Attach flexible connectors (hoses) between the parts. 6. Save your Meter-Out project.


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Software Procedure: Adjusting the Controls 1. Open LVVL Virtual Lab for LVSim (LVSIM_HYD version). 2. Open your Meter-Out XX file. 3. Adjust the pressure relief valve to create 200 psig (13.79 bar) in the circuit.

NOTE: To check the pressure, move the control lever on the Directional Valve to its various positions. You can lock the lever in position when the left-mouse button is released while pressing CTRL key. The control lever returns to the center position when you click on it.

4. Adjust the flow control to deliver 1 liter per minute while watching the

Flowmeter and moving the Directional Valve to various positions.


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Software Procedure: Moving the Actuator NOTE: By adjusting the pressure and flow rate to specific numbers, you control the speed of the rod.

1. Open LVVL Virtual Lab for LVSim (LVSIM_HYD version). 2. Open your Meter-Out XX file. 3. Using a watch, clock, or stopwatch, or by counting slowly, count how many

seconds it takes for the actuator rod to fully extend in the next step. 4. Move the actuator rod out of the cylinder using the lever on the Directional

Valve handle. 5. Count how many seconds it takes for the actuator rod to retract in the next step. 6. Move the actuator rod into the cylinder using the DCV handle. 7. Save your Meter-Out project.

NOTE: Does the rod take as much time to go back into the cylinder as it does to extend?

Software Procedure: Placing a Control Downstream To control the flow rate in both directions perform the following steps. 1. Open LVVL Virtual Lab for LVSim (LVSIM_HYD version). 2. Open your Meter-Out XX file. 3. Select File>Save As and then rename and save this file as Control Downstream

XX with your initials in place of the XX. (For example: Control Downstream GP)

4. Stop the Power Unit. 5. Remove the existing Flow Control Valve and replace the connections with a hose.


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6. Install a Flow Control Valve on the work surface between the Directional Valve and the return port of the Power Unit.

NOTE: Fluid from the Power Unit will flow through the Flow Control Valve as the directional lever is pushed or pulled. However, the setting percentage determines the speed of the piston movement.

7. Start the Power Unit. 8. Count how many seconds it takes for the actuator rod to retract in the next step. 9. Move the actuator rod in and out of the cylinder by pushing and pulling the DCV

handle.

NOTE: Does it take as many seconds as it did before you moved the Flow Control Valve between the Directional Valve and pressure port?

10. Set the Flow Control Valve to a setting of 5% and observe the speed of the piston

movement as you move the Directional Control lever. 11. Set the Flow Control Valve at 95% and observe the speed of the piston

movement as you move the Directional Control lever.

NOTE: How does the setting of the Flow Control Valve affect the speed of the piston movement?

12. Save your Control Downstream XX file. 13. Close the LVVL Virtual Lab LabSim program. Once you've completed the procedure, click on the Forward arrow to resume the multimedia presentation.

Mechanical Systems Topic 7 – Levers

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TOPIC 7 – LEVERS

Objective When you have completed this topic, you will be able to determine the mechanical advantage of a lever, identify the three components of a lever, and calculate the amount of force or distance needed to move an object with a lever.

Overview The concept of the lever is important to the quality of life we have today. It is one of the first mechanical principles recognized and used by humans. Can you imagine moving huge stones without a pry bar? Cavemen would have been unable to shape caves. Boulders for building pyramids might still lie in stone quarries. Inventors built civilizations by applying the mechanical advantage of levers, such as pry bars and cranes, to fulfill their dreams. Today we enjoy the advantages of hammers, wheelbarrows, and simple machines like fishing rods and baseball bats. In this topic, you will study the Principle of the Lever and identify the three parts of a lever. You will also build three types of levers and calculate the mechanical advantage for each.

New Terms and Words counterbalance – to balance or oppose with an equal weight or force. distance advantage – the ratio of the output distance to the input distance; for example, a short motion creates a longer one. fulcrum – the support on which a lever turns. (This is a Latin word for “support.”) lever – a long bar that rests or rotates on a pivot point. load – any object or resistance, including friction, that a machine must move. onager – a heavy catapult that was used in ancient and medieval times. principle – a rule or law concerning the functioning of natural phenomena or mechanical processes. prize – a metal bar for moving heavy objects. resultant force – the combined effect of two or more forces acting on a load.


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Activity 1 – Leverage

Objective When you have completed this activity, you will have the knowledge and skills to explain the fundamental principles and parts of a lever. You will be able to: • identify the three parts of a lever. • demonstrate how levers create a mechanical advantage. • explain the Principle of the Lever. • calculate mechanical advantage.

General Procedure: An Experiment in Balance 1. Tape a pencil to your desk. 2. Balance the ruler across the pencil. 3. Place one washer on one end of the ruler. 4. Place a washer on the other end of the ruler. 5. Try to keep the center of the ruler over the pencil. 6. Move the washers so that they balance the ruler.

General Procedure: An Experiment in Balance and Mechanical Advantage 1. Tape a pencil to your desk. 2. Balance the ruler across the pencil. 3. Place one washer on one end of the ruler. 4. Stack three washers on top of each other and place them on the other end of the

ruler. 5. Move the ruler over the pencil to make the washers balance. Once you've completed the procedure, click on the Forward arrow to resume the multimedia presentation.


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Activity 2 – Cranes and Prizes

Objective When you have completed this activity, you will have the knowledge and skills to explain the fundamental principles and parts of a first-class lever. You will be able to: • locate the three parts of a first-class lever. • calculate the mechanical advantage of a first-class lever.

General Procedure: Repeating the Experiment in Balance and Mechanical Advantage 1. Tape a pencil to your desk. 2. Balance the ruler across the pencil. 3. Place one washer on one end of the ruler. 4. Stack three washers on top of each other and place them on the other end of the

ruler. 5. Move the ruler over the pencil to make the washers balance.

General Procedure: A Second Experiment in Balance and Mechanical Advantage 1. Tape a pencil to your desk. 2. Place the 3 inch (7.62 cm) mark of the ruler over the pencil. 3. Add washers to the shorter end of the ruler until it balances. 4. Place one washer on the longer end of the ruler. 5. Place three more washers on the shorter end of the ruler. 6. Carefully move the washers until you balance the ruler. The single washer should be three times farther from the fulcrum than the stack of washers on the other end of the ruler. Once you've completed the procedure, click on the Forward arrow to resume the multimedia presentation.


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Activity 3 – Wheelbarrows and Bottle Openers

Objective When you have completed this activity, you will have the knowledge and skills to explain the fundamental principles and parts of a second-class lever. You will be able to: • locate the three parts of a second-class lever. • calculate the mechanical advantage of a second-class lever.

General Procedure: An Experiment with a Second-Class Lever 1. Place the ruler on your desk. Let 1 inch (2.54 cm) of the ruler hang past the end

of the desk. 2. Take the newton scale and hold it by the top wire hanger. 3. Carefully lift the end of the ruler with the hook of the scale just high enough to

get a reading. This reading is the weight of the ruler. Record the weight on a piece of paper.

4. Stack four washers on top of each other and place them on the end of the ruler

that hangs past the end of the desk. 5. Take the newton scale and hold it by the top wire hanger. 6. Carefully lift the end of the ruler that has the washers with the hook of the

scale. Lift the ruler just high enough to get a reading on the scale, and be careful that the washers don’t fall off.

7. Read the scale. 8. Subtract the weight of the ruler from the reading on the scale. 9. Move the washers to the 6 inch (15.24 cm) mark on the ruler. 10. Carefully lift the end of the ruler with the hook of the scale. 11. Read the scale. 12. Subtract the weight of the ruler from the reading on the scale.


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When the washers are at the 6 inch (15.24 cm) mark, the scale reading will be half of what it was when the washers were at the end of the ruler. When the washers are at the end of the ruler, they are twice the distance from the fulcrum as they were at the 6 inch (15.24 cm) mark. The mechanical advantage, therefore, is 2:1. Once you've completed the procedure, click on the Forward arrow to resume the multimedia presentation.


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Activity 4 – Catapults and Fishing Rods

Objective When you have completed this activity, you will have the knowledge and skills to explain the fundamental principles and parts of a third-class lever. You will be able to: • locate the three parts of a third-class lever. • calculate the mechanical advantage of a third-class lever.

General Procedure: An Experiment with a Third-Class Lever 1. Weigh the ruler using the newton scale. Record the weight on a piece of paper. 2. Place the ruler on your desk. Let 7 inches (17.78 cm) hang past the end of the

desk. Use your finger to hold the other end of the ruler to the desk. (Your finger will be the fulcrum.)

3. Stack four washers on top of each other and place them on the end of the ruler

that hangs past the end of the desk. 4. Take the newton scale and hold it by the top wire hanger. Hook the scale under

the ruler at the 6 inch (15.24 cm) mark. 5. Carefully lift the ruler with the hook of the scale, making sure that the washers

don’t fall off. 6. Read the scale. 7. Subtract the weight of the ruler from the reading on the scale. The scale reading will be twice the actual weight of the washers. The washers at the end of the ruler (the output) are twice the distance from the fulcrum as the scale at the 6 inch (15.24 cm) mark on the ruler (the input). The mechanical advantage is 1:2. Once you've completed the procedure, click on the Forward arrow to resume the multimedia presentation.

Mechanical Systems Topic 8 – Resistance

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TOPIC 8 – RESISTANCE

Objective When you have completed this topic, you will be able to identify the parts of the Exploring Mechanisms Trainer, measure friction using a newton scale, and read a table of friction coefficients. You will also be able to define sliding and rolling friction and understand the purpose of lubrication.

Overview If friction didn't exist, there would be chaos everywhere. Cars and trains wouldn't go or stop, and people wouldn't be able to walk. Rolling over in bed would be impossible. Men would have very long beards, while women's makeup would slide right off. Forget about flying airplanes, let alone jumping out; parachutes wouldn't work either. Simple tasks like sharpening a knife would also be impossible. Friction is the resistance to movement between two bodies in contact. The idea of friction touches on very fundamental laws of physics, including concepts of weight, mass, and velocity. When using clamps and conveyors, you want to increase friction so that the material being moved does not fall off. When making in-line skates roll faster, you want to reduce friction so that the wheels spin more freely around the bearings. In this topic, you will use simple materials such as a block and a weight scale to experiment with the fundamentals of resistance. You will use parts of the Exploring Mechanisms Trainer to measure different kinds of friction. You will also learn to read tables similar to the ones engineers use to determine friction between materials.


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New Terms and Words adhesion – the physical attraction or joining of two substances. coefficient − a number that is a measure of some property; in this case, the property is friction. inertia – a property of matter where an object in motion remains in motion and when at rest remains at rest, unless acted upon by an external force. lubricate − to make slippery or smooth. peaks − the submicroscopic contact points between two objects. At these isolated contact points, molecular bonding takes place. Force is required to break these bonds and allow one object to move along the other. race − the groove or track in which the bearings roll. ratio – the relationship between two numbers, expressed as the division of one number by the other. Thus, a ratio of 12 to 3, expressed as 12/3, or 4, means that 12 contains 3 four times. static friction – the resistance to movement between two bodies at rest and in contact with each other. viscosity – the property of a fluid that resists flow when a force is applied. High-viscosity fluids flow slowly and with difficulty; low-viscosity fluids flow quickly and easily. wear – gradual erosion of contacting surfaces.


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Activity 1 – The Exploring Mechanisms Trainer

Objective When you have completed this activity, you will have the knowledge and skills to identify the parts of the Exploring Mechanisms Trainer. You will be able to: • locate the parts mounted on the front of the trainer. • explain the purpose of each part. • identify parts within the storage area.


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Activity 2 – Static Friction

Objective When you have completed this activity, you will have the knowledge and skills to measure and calculate static friction. You will be able to: • measure static friction. • calculate the coefficient of static friction. • read a table to determine the coefficient of static friction for several materials.

General Procedure: Weighing the Object You will now perform your own static friction experiment. To calculate the coefficient of static friction for the wood block, perform the following steps. 1. Remove the wood block and the spring scale from the trainer storage area. 2. Use the spring scale to measure the weight of the block. Observe the reading on

the scale and record the weight (in newtons) in your Student Guide/Portfolio.


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General Procedure: Measuring Static Friction 1. Lay the wood block on a rug or rubber mat and attach the spring scale to the

block as shown in the graphic. (If a rug or mat is not available, use a smooth surface.)

NOTE: You will not know the friction between the wood block and the surface you've chosen until you perform the following steps.

2. Slowly pull the block with the spring scale until it just starts to move, then stop.

Look at the spring scale and record the reading (in newtons) in your Student/Guide Portfolio.

3. Repeat the first two steps a few times and record the highest reading (in

newtons) just before the block starts to move. This is the force required to overcome static friction.

Once you've completed the procedure, click on the Forward arrow to resume the multimedia presentation.


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Activity 3 – Dynamic Friction

Objective When you have completed this activity, you will have the knowledge and skills to calculate dynamic friction. You will be able to: • measure dynamic friction. • calculate the coefficient of dynamic friction. • read a table to determine the coefficient of dynamic friction for several

materials. • define lubrication, sliding friction, and rolling friction.

General Procedure: Measuring Dynamic Friction 1. Lay the wood block on a rug or rubber mat and attach the spring scale to the

block as shown in the graphic. (If a rug or mat is not available, use a smooth surface.)

NOTE: You will not know the friction between the wood block and the surface you've chosen until you perform the following steps.

2. Slowly pull the block with the spring scale. Look at the spring scale as the block

slides along the surface, and record the reading (in newtons) in your Student Guide/Portfolio.

3. Repeat the first two steps a few times and record the average reading (in

newtons) in your Student Guide/Portfolio. This is the average force required to overcome dynamic friction.

4. Calculate the coefficient of dynamic friction. You will use the same equation you

used to calculate the coefficient of static friction: Cf = Of ÷ Ow. Record your answer in your Student Guide/Portfolio.

Once you've completed the procedure, click on the Forward arrow to resume the multimedia presentation.

Mechanical Systems Topic 9 – Drivers

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TOPIC 9 – DRIVES

Objective When you have completed this topic, you will be able to explain the benefits of friction drives and positive drives in industry. You will install, align, and operate belts, pulleys, gears, and chains on the Exploring Mechanisms Trainer. You will also observe how drives move the lift mechanism of the trainer. Overview In this topic, you will focus on two types of drives – friction and positive. Friction drives include round, flat, and v-belts. Positive drives include synchronous belts, gear trains, and chain drives. There are more types of drives, but in this topic you will study the ones used in many of the machines you see every day. Belts drive air-conditioning equipment, electric generators, and steering pumps in the family car. Gears and chains hidden inside the engine transfer energy to move the car forward. Drives are a special category of mechanical engineering. In this topic, you will learn about the fascinating history of drives in the growth of industry. Many companies design and manufacture drives. These drives are then used by other companies to make products.

New Terms and Words centrifugal force – the force that drives or propels an object away from a center or axis. drives – mechanisms that move a machine or machine part. light-duty – requiring a very small force to move or operate a device. positive drives – drives which prevent slipping. ratio – the relationship between two numbers, expressed as the division of one number by the other. sheave – a wheel or pulley that has a grooved circumference. torque – a twisting or turning force.


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Activity 1 – Friction Drives

Objective When you have completed this activity, you will have the knowledge and skills to identify, install, and operate friction drives. You will be able to: • install and operate the friction drive on the front of the trainer. • describe how a friction drive moves the lift mechanism of the trainer. • explain how belts are used to change direction and permit misalignment. • change belt speed by changing pulleys.

General Procedure: Safe Operation When working with the Exploring Mechanisms Trainer, be aware of the following:

WARNING: You can hurt your fingers by catching them between belts or gears.

When running the trainer, keep your hands outside the area enclosed by the safety door.

CAUTION: You can damage the trainer by placing objects between the belts, pulleys, or gears. Check to make sure that there is nothing that can get caught in the mechanisms on the front of the trainer. If there is something that can interfere with the safe operation of the trainer, call your instructor.


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General Procedure: Removing the Pulleys and Belt To gain hands-on experience with belt installation, you will remove the belt and pulleys from the front of the trainer, then replace them with the o-ring and o-ring pulleys.

NOTE: There may be a chain around the pulleys in place of the belt, depending on the previous students' progress. Also, the pulleys that are currently on the trainer may differ from the pulleys shown in the video you are about to see.

To remove the existing pulleys and belt (or chain), perform the following steps: 1. Take the small Allen (six-sided) wrench from the storage area on top of the

trainer. 2. Insert one end of the wrench into the Allen screws at the sides of the four pulleys

and loosen the Allen screws. 3. Loosen the tension adjustment knob and slide it down as far as it can go. 4. Slide the pulleys and belt (or chain) off the axles and place them in the storage

area.

General Procedure: Installing the Friction Pulleys To install the friction pulleys, perform the following steps (the pulleys and belt you are about to install make up the friction drive): 1. Remove the o-ring and the four round, grooved pulleys from the storage area. 2. Place the largest pulley on the driven gear axle. 3. For convenience, turn the Allen screw in the pulley so it faces toward you. 4. Slide the pulley over the axle until the end of the axle is even with the pulley

end. Tighten the screw with the Allen wrench. 5. Place and tighten the 1-inch (2.54 cm) pulley onto the topmost idler axle. 6. Place and tighten the 1.5-inch (3.81 cm) pulley onto the tension adjuster axle. 7. Place and tighten the 2-inch (5.08 cm) pulley onto the same axle as the o-ring

pulley at the lower center of the trainer.


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General Procedure: Installing the Lift Pulley To install the lift pulley, perform the following steps: 1. Place the o-ring over the pulleys as shown in the drawing on the upper left of the

trainer. 2. Slide the tension adjustment knob upward until the o-ring gives a light

resistance, then tighten it.

NOTE: Make sure the string is passed through the hole in the axle on the top lift axle, then knotted.

3. Pass the string around and under the lift pulley and catch the hook at the end of the string over the lift axle.

General Procedure: Observing Your Lift Installation To observe the success of your lift installation, perform the following steps: 1. Close the safety door. 2. If the trainer is safe to operate, plug the power cord into the power outlet

(receptacle), switch the lift control to RAISE, then press the POWER switch to the ON position, then press and hold down the MOTOR RUN START button.

3. Let the lift continue until it stops. The upper stop sensor disconnects the power. 4. Next, count the seconds as the lift travels from the upper to the lower stop.

Switch the lift control to LOWER, then permit the lift to lower until it stops by the lower stop sensor.

5. Release the START button. Once you've completed the procedure, click on the Forward arrow to resume the multimedia presentation.


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Activity 2 – Positive Drives

Objective When you have completed this activity, you will have the knowledge and skills to identify, install, and operate positive drives. You will be able to: • install, align, and operate belts, pulleys, gears, and chains. • specify the benefits of positive drives, such as precise timing and strength. • explain drive rotation and changes in direction.

General Procedure: Observing Your Lift Installation To gain experience with synchronous belt installation, you will remove the existing belt and pulleys and replace them with the synchronous belt and pulleys. Then you will run the trainer to see how the synchronous belt and pulleys operate. To remove the o-ring pulleys and belt, perform the following steps: 1. Take the small Allen (six-sided) wrench from the storage area. 2. Insert one end of the wrench into the Allen screws at the sides of the four pulleys

and loosen the Allen screws. 3. Loosen the tension adjustment knob and slide it down as far as it can go. 4. Slide the pulleys and o-ring (or chain) off the axles and place them in the storage

area.

General Procedure: Installing the Synchronous Pulleys To install the synchronous pulleys, perform the following steps: 1. Remove the synchronous toothed belt and the four grooved pulleys from the

storage area. 2. Place the largest pulley on the driven gear axle. For convenience, turn the Allen

screw in the pulley so it faces toward you. 3. Slide the pulley over the axle until the end of the axle is even with the pulley

end. Tighten the screw with the Allen wrench. 4. Place and tighten the 1-inch (2.54 cm)pulley onto the topmost idler axle.


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5. Place and tighten the 1.5-inch (3.81 cm) pulley onto the tension adjuster axle. 6. Tighten the 2-inch (5.08 cm) pulley onto the same axle as the o-ring pulley at the

lower center of the trainer.

General Procedure: Installing the Synchronous Belt To install the synchronous belt, perform the following steps:

1. Place the synchronous belt over the pulleys as shown in the drawing at the

upper left of the trainer. 2. Push the ridges of the belt into the grooves of the pulley. 3. Slide the tension adjustment knob upward until the belt gives a light resistance,

then tighten it. Make sure the string is passed through the hole in the axle on the top lift axle, then knotted. Pass the string around and under the lift pulley and catch the hook at the end of the string over the lift axle.

General Procedure: Observing Your Lift Installation To observe the success of your lift installation, perform the following steps: 1. Close the safety door. 2. If the trainer is safe to operate, plug the power cord into the receptacle, switch

the lift control to RAISE, then press the POWER switch to the ON position, then press and hold down the MOTOR RUN START button.

3. As the lift rises, watch the belt. You may see the belt twist slightly near the

pulleys. Let the lift continue until it stops. The upper stop sensor disconnects the power.

4. Next you will count the seconds as the lift travels from the upper stop to the

lower stop. 5. Switch the lift control to LOWER, then permit the lift to lower until it stops by

the lower stop sensor. Release the START button.

General Procedure: Changing the Gears Next you will change the gears on the trainer. But before you do, loosen the tension adjustment knob and remove the synchronous belt from around the pulleys. Then remove the largest pulley from the driven gear axle.


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To change the speed of the gears, perform the following steps:

1. Remove the 30t (30 teeth) and 42t (42 teeth) nylon spur gears from the drive and

driven axles. 2. Remove the 24t (24 teeth) and 48t (48 teeth) nylon spur gears from the storage

area. You will install these two gears onto the drive axles.

NOTE: Notice that the diameter of the drive gear is larger than the diameter of the driven gear.

3. Install the 24t gear onto the driven (upper) axle. 4. Install the 48t gear onto the drive (lower) axle. 5. Tighten the two new gears onto the shafts. 6. Tighten the Allen screws with the Allen wrench. When you are finished, reinstall the largest pulley onto the driven gear axle and place the synchronous belt around the pulleys.

General Procedure: Observing the Change in Speed The lift on the trainer will now move at a different speed because you changed the speed of the gears (i.e., the gear ratio). To observe the change in speed, perform the following steps: 1. Close the safety door. 2. If the trainer is safe to operate, plug the power cord into the receptacle, switch


3. Let the lift continue until it stops. The upper stop sensor disconnects the power. 4. Count the seconds as the lift travels from the upper to the lower stop. Switch the

lift control to LOWER, then permit the lift to lower until it stops by the lower stop sensor. Release the START button.


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General Procedure: Removing the Synchronous Pulleys and Belt To gain experience with chain drive installation, you will remove the synchronous pulleys and belt and replace them with the pulleys and chain. Then you will run the trainer to see how the pulleys and chain operate. To remove the synchronous pulleys and belt, perform the following steps: 1. Take the small Allen (six-sided) wrench from the storage area. 2. Insert one end of the wrench into the Allen screws at the sides of the four pulleys

and loosen the Allen screws. 3. Loosen the tension adjustment knob and slide it down as far as it can go. 4. Slide the pulleys and belt off the axles and place them in the storage area.

General Procedure: Installing the Chain Pulleys To install the chain pulleys, perform the following steps: 1. Remove the chain and the four-toothed pulleys from the storage area. 2. Place the largest pulley on the driven gear axle. For convenience, turn the Allen

screw in the pulley so it faces toward you. 3. Slide the pulley over the axle until the end of the axle is even with the pulley

end. Tighten the screw with the Allen wrench. 4. Place and tighten the 1-inch (2.54 cm) pulley onto the topmost idler axle. 5. Place and tighten the 1.5-inch (3.81 cm) pulley onto the tension adjuster axle. 6. Tighten the 2-inch (5.08 cm) pulley onto the same axle as the o-ring pulley at the

lower center of the trainer.

General Procedure: Aligning the Chain Pulleys To align the pulleys, perform the following steps: 1. Use a ruler to align the pulleys. 2. Loosen the Allen screw in the hub of the misaligned pulley. 3. Place the edge of the ruler across the sides of two pulleys. 4. Adjust the pulleys so they lie on the same plane. 5. Tighten the Allen screw.


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General Procedure: Installing the Chain To install the chain, perform the following steps: 1. Place the chain over the pulleys as shown in the drawing on the upper left of the

trainer. 2. Slide the tension adjustment knob upward until the chain gives a light

resistance, then tighten it. 3. Make sure the string is passed through the hole in the axle on the top lift axle,

then knotted. 4. Pass the string around and under the lift pulley and catch the hook at the end of

the string over the lift axle.

General Procedure: Running the Trainer To run the trainer, perform the following steps: 1. Close the safety door. 2. If the trainer is safe to operate, plug the power cord into the receptacle, switch


3. As the lift rises, watch the chain. Let the lift continue until it stops. The upper stop sensor disconnects the power.

4. Switch the lift control to LOWER, then permit the lift to lower until it stops by the lower stop sensor.

5. Release the START button. Once you've completed the procedure, click on the Forward arrow to resume the multimedia presentation.


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Mechanical Systems Topic 10 – Pulleys

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TOPIC 10 – PULLEYS

Objective When you have completed this topic, you will be able to calculate the mechanical advantage of different types of pulleys. You will understand the importance of pulleys in the history of technology. You will also identify similarities between how a wheel or pulley works and how a lever works.

Overview A machine is something that allows a person to use his or her energy more effectively. There are two simple machines: the inclined plane and the lever. Primitive man made use of the inclined plane when he threw stones downhill toward threatening opponents, and rolled boulders and logs uphill to make a defensive barrier. Hills and mountains are nature’s inclined planes. A lever multiplies a workman's muscle power. Both the inclined plane and the lever trade increased distance for decreased force (the greater the distance, the less force you need to exert). A wheel is a special type of lever that includes an inclined plane; a pulley is a form of wheel. This topic expands on these ideas. The pyramids in Egypt are monuments to the ability of architects in the earliest civilizations to move incredible amounts of earth and stone. They used the inclined plane, the lever, and the wheel to accomplish this. The fact that they had not yet discovered the screw and the block and tackle makes their accomplishments even more astounding. Although these simple machines are the oldest of technologies, modern society cannot exist without them. To create the future, you must master the simplest, and oldest, of machines.


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New Terms and Words aqueducts – structures built to carry a large amount of water a long distance. block and tackle – pulley blocks used for hoisting with a rope. compound bow − a bow that has multiple-grooved pulleys at the ends, through which strong string is passed to provide force for arrows. fixed pulley − an anchored pulley; one that does not move freely. fulcrum − the support on which a lever turns. fortresses – walled defenses that sometimes included an entire town. lever − a long bar that rests or rotates on a pivot point. ore − dirt or stone from which a valuable mineral is extracted. radius − a line from the center of a circle to its circumference. resultant force – the combined effect of two or more forces acting on a load. winch – a powerful machine with a drum on which to coil a rope or chain


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Activity 1 – Fixed Pulleys

Objective When you have completed this activity, you will have the knowledge and skills to identify and apply fixed pulleys. You will be able to: • describe the history of the fixed pulley and its uses. • use a fixed pulley to change the direction of force. • explain how the lever and inclined plane within a pulley work. • specify how a fixed pulley is used to reduce effort and increase work.


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Activity 2 – Movable Pulleys

Objective When you have completed this activity, you will have the knowledge and skills to identify and select movable pulleys, as well as a winch. You will be able to: • calculate the mechanical advantage of a winch and a block and tackle. • explain the design and uses of these machines. • describe the history of both machines.

APPENDICES

Mechanical Systems Appendix A – Operating Safety

A-1

Appendix A – Operating Safety You will follow the safety rules for these three areas: • maintaining and connecting hydraulic hoses. • running and stopping the Power Unit. • disconnecting and storing components.

Bending a Flexible Connecting Hose An experienced technician will know just how far to bend a flexible connecting hose. The minimum bend diameter of the hose is 6 inches (152.4 mm). If you force the ends of the semicircle (hose) closer together than 6 inches, the hose may tear.

Testing the Connection Fittings The connection fittings should be in working condition. To test this, do the following: 1. Move each ball inside the fitting with your finger. 2. If any ball sticks, clean the ball lock and apply fresh oil. (Stuck ball locks will

prevent proper connections.) 3. Check that the knurled ring moves freely. 4. If the ring is too difficult to move, get a new hose.

Dangerous Pressure

WARNING: The Power Unit can produce pressures approaching 1000 psig (70 bar). Air and hydraulic fluid can be trapped inside flexible connecting hoses. If so, when you remove a connector or if the hose leaks, a high-pressure spray of hydraulic fluid could pierce your skin.

Even in the less dangerous situation of a fluid spill, wear gloves; you could be allergic to some fluids.

If you detect a hydraulic leak, DO NOT ATTEMPT TO COVER OR REPAIR THE LEAK. The high-pressure fluid may injure someone in the area. • Call the instructor. • If it is possible to disconnect the power without injury, do so. • Seek medical help for any injury.


A-2

Before Starting the Power Unit Always perform the following safety procedures before you start the Power Unit. • Know and use all safety precautions. • Wear approved eye protection, cloth-lined rubber gloves, and protective clothing. • Clear the area of hazards. • Prevent others from coming too close to the unit. • Report any dangerous conditions to your instructor. • Do not use a damaged flexible connecting hose. • Give any damaged hoses to your instructor for replacement.

When Running the Power Unit The following safety procedures protect you and others while you operate the Power Unit: • Be sure you are wearing safety goggles and protective clothing. • If you notice a leak, turn the Power Unit off. • Move out of the way of leaks. • Handle fluid with cloth-lined rubber gloves. • If any fluid gets on your skin, wash it off immediately. • Keep cloth or paper towels nearby to wipe oil from the parts. • Keep a fire extinguisher nearby. Monitoring Fluid Temperatures It is important to continually monitor conditions while operating the Power Unit. The temperature and pressure of the hydraulic fluid are valuable clues to conditions inside the unit. Overheated fluid may no longer lubricate parts properly. Also, overheated hydraulic fluid can flash into fire.

When Stopping the Power Unit Stopping the Power Unit is the most dangerous part of the activity. Part of the circuit may hold pressure between closed valves. Air compressed between valves can spray fluid in any direction. To end an activity in which the Hydraulics I Training System is used, perform the following procedure:


A-3

1. Turn the Power Unit switch to the OFF position. 2. Drain fluid back into the reservoir for five minutes. Make sure there is no

pressure in any part of the system. Whenever possible, release all pressure through a drain valve into the reservoir.

NOTE: A connector that is difficult to remove may still be under pressure.

3. Point the connector away from yourself and others while connecting or disconnecting a flexible connecting hose. Remove all flexible connecting hoses from the Power Unit.







Quick-Connect Inspection • Wipe the hose clean. • Remove the quick-connect fitting by pushing the hose toward the connector. • Pull back on the sliding ring. The locking ring should move smoothly. • Pull the hose away from the connection. • Drip excess oil into the drain pan or a towel. • Wipe the connection fitting clean and inspect the quick-connect fitting. • Inspect the hose for cuts, breaks, splits, or bulges. • Replace damaged hoses. • Wash oil from the exterior.


A-4

Hydraulic Fluid Inspection It is extremely important to use clean hydraulic fluid at all times. Dirt in the fluid will act like sandpaper on seals and shafts. Fluid will escape from worn seals. Worn shafts will move out of alignment, creating further seal damage. When you are inspecting the fluid, look for metal and other particles; these damage hydraulic parts. They are evidence of mechanical breakage. Very small particles pass though the filter. Clean-looking oil may still be abrasive. Change the oil on a regular schedule. The oil should be changed each time the power unit has run for 50 hours.

Mechanical Systems Appendix B – Internet Resources

B-1

Appendix B – Internet Resources In many countries, engineers join associations to meet others with the same interests. Before computers, engineers formed committees to solve common problems such as deciding standard methods of measurement. The Internet user might consider these committee meetings as a form of chat room. The following institutions are a resource for continuing education in engineering fields of study. The American Society of Mechanical Engineers (ASME) maintains a website for the mechanical engineering community. You will find articles and authors on a wide range of engineering interests. The ASME is a professional society that offers a variety of publications and services. Student memberships are available. www.asme.org The American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) is a specialized engineering community. These engineers have interests in common with the ASME, but their main concentration is in the areas of human comfort, food preservation, manufacturing processes requiring thermal transfer, and other areas concerning thermodynamics. ASHRAE is a professional society that offers a variety of publications and services. Student memberships are available. www.ashrae.org The Air-Conditioning and Refrigeration Institute (ARI) publishes a list comparing appliances to industry standards. ARI offers a variety of publications and services. www.ari.org

Documents

NOT YET RELEASED 37208-E0 MechanicalSystems CG ED2 PR2€¦ · Lab-Volt License Agreement By using the software in this package, you are agreeing to become bound by the terms of this