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WorkbookTP 800
With CD-ROM
Festo Didactic
574166 en
Mobile Hydraulics
TP
D (X2) A B
LS
C (X1)
P
C
T
B
LSLS2
T
A
D
LS1
P
Order no. 574166
Revision level: 03/2013
Authors: Ulrich Schedel, Levent Unan
Editor: Christine Löffler
Graphics: Doris Schwarzenberger
Layout: 03/2013, Susanne Durz, Christine Löffler
© Festo Didactic SE, Rechbergstraße 3, 73770 Denkendorf, Germany, 2015
All rights reserved.
+49 711 3467-0 www.festo-didactic.com
+49 711 34754-88500 did@de.festo.com
The purchaser shall receive a single right of use which is non-exclusive, non-time-limited and limited
geographically to use at the purchaser's site/location as follows.
• The purchaser shall be entitled to use the work to train his/her staff at the purchaser's site/location and
shall also be entitled to use parts of the copyright material as the basis for the production of his/her
own training documentation for the training of his/her staff at the purchaser's site/location with
acknowledgement of source and to make copies for this purpose. In the case of schools/technical
colleges and training centres, the right of use shall also include use by school and college students and
trainees at the purchaser's site/location for teaching purposes.
• The right of use shall in all cases exclude the right to publish the copyright material or to make this
available for use on intranet, Internet and LMS platforms and databases such as Moodle, which allow
access by a wide variety of users, including those outside of the purchaser's site/location.
• Entitlement to other rights relating to reproductions, copies, adaptations, translations, microfilming and
transfer to and storage and processing in electronic systems, no matter whether in whole or in part,
shall require the prior consent of Festo Didactic.
© Festo Didactic 574166 III
Contents
Intended use _____________________________________________________________________________ VIII
Preface ________________________________________________________________________________ IX
Introduction ______________________________________________________________________________ XI
Work and safety instructions ________________________________________________________________ XII
Mobile hydraulics training package (TP 800) _________________________________________________ XIV
Learning objectives _________________________________________________________________________ XV
Allocation of learning objectives to exercises __________________________________________________ XVII
Equipment set _____________________________________________________________________________ XX
Allocation of components to exercises ______________________________________________________ XXVII
Notes for the teacher/trainer ________________________________________________________________ XXX
Structure of the exercises _________________________________________________________________ XXXI
Component designations __________________________________________________________________ XXXI
CD-ROM contents ________________________________________________________________________ XXXI
Exercises and solutions: Mobile hydraulics, basic level working hydraulics (TP 801)
Exercise 1-1: Examining performance for a controller using constant displacement pump
and fixed pressure limitation _____________________________________________________ 3
Exercise 1-2: Examining performance for a controller using constant displacement pump
and adjusted pressure limitation using open-centre load-sensing pressure balance ______ 13
Exercise 1-3: Examining performance of speed control using a 6/3-way proportional valve ____________ 23
Exercise 1-4: Examining energy efficiency of speed control in an open-centre load-sensing system _____ 31
Exercise 1-5: Moving and holding a load with a 6/3-way proportional valve ________________________ 41
Exercise 1-6: Moving and holding a load with a piloted non-return valve ___________________________ 51
Exercise 1-7: Moving and holding a load with a pressure-relief valve as counter pressure _____________ 59
Exercise 1-8: Moving and holding a load with a counterbalancing valve ____________________________ 69
Exercise 1-9: Examining parallel, series and tandem configurations _______________________________ 79
Exercises and solutions: Mobile hydraulics, advanced level steering system (TP 802)
Exercise 2-1: Examining the steering valve in a hydrostatic steering system ________________________ 91
Exercise 2-2: Examining steering when external forces are exerted ________________________________ 99
Exercise 2-3: Examining overload protection for steering _______________________________________ 107
Exercise 2-4: Examining a steering system with priority function _________________________________ 115
Exercise 2-5: Designing a steering system for centre-pivot steering ______________________________ 123
IV © Festo Didactic 574166
Exercises and solutions: Mobile hydraulics, advanced level working hydraulics (TP 803)
Exercise 3-1: Examining a hydraulic system with load-sensing-controlled variable displacement pump _ 133
Exercise 3-2: Examining the load hold function _______________________________________________ 143
Exercise 3-3: Remotely controlling proportional directionalcontrol valves using a hydraulic joystick ___ 151
Exercise 3-4: Setting a (volumetric) flow rate independent of load _______________________________ 159
Exercise 3-5: Setting the volumetric flow rate using a load-sensing-controlled pump unit ____________ 169
Exercise 3-6: Examining a load-sensing system with upstream pressure balance ___________________ 179
Exercise 3-7: Examining a load-sensing system with downstream pressure balance _________________ 191
Exercises and worksheets: Mobile hydraulics, basic level working hydraulics (TP 801)
Exercise 1-1: Examining performance for a controller using constant displacement pump
and fixed pressure limitation _____________________________________________________ 3
Exercise 1-2: Examining performance for a controller using constant displacement pump
and adjusted pressure limitation using open-centre load-sensing pressure balance ______ 13
Exercise 1-3: Examining performance of speed control using a 6/3-way proportional valve ____________ 23
Exercise 1-4: Examining energy efficiency of speed control in an open-centre load-sensing system _____ 31
Exercise 1-5: Moving and holding a load with a 6/3-way proportional valve ________________________ 41
Exercise 1-6: Moving and holding a load with a piloted non-return valve ___________________________ 51
Exercise 1-7: Moving and holding a load with a pressure-relief valve as counter pressure _____________ 59
Exercise 1-8: Moving and holding a load with a counterbalancing valve ____________________________ 69
Exercise 1-9: Examining parallel, series and tandem configurations _______________________________ 79
Exercises and worksheets: Mobile hydraulics, advanced level steering system (TP 802)
Exercise 2-1: Examining the steering valve in a hydrostatic steering system ________________________ 91
Exercise 2-2: Examining steering when external forces are exerted ________________________________ 99
Exercise 2-3: Examining overload protection for steering _______________________________________ 107
Exercise 2-4: Examining a steering system with priority function _________________________________ 115
Exercise 2-5: Designing a steering system for centre-pivot steering ______________________________ 123
Exercises and worksheets: Mobile hydraulics, advanced level working hydraulics (TP 803)
Exercise 3-1: Examining a hydraulic system with load-sensing-controlled variable displacement pump _ 133
Exercise 3-2: Examining the load hold function _______________________________________________ 143
Exercise 3-3: Remotely controlling proportional directional control valves using a hydraulic joystick ___ 151
Exercise 3-4: Setting a (volumetric) flow rate independent of load _______________________________ 159
Exercise 3-5: Setting the volumetric flow rate using a load-sensing-controlled pump unit ____________ 169
Exercise 3-6: Examining a load-sensing system with upstream pressure balance ___________________ 179
Exercise 3-7: Examining a load-sensing system with downstream pressure balance _________________ 191
© Festo Didactic 574166 V
Basics of mobile hydraulics
1 Introduction _______________________________________________________________________ I-5
2 Fundamentals of hydraulics __________________________________________________________ I-7
2.1 Basic principles of pressure and flow control valves _______________________________________ I-7
2.2 Pressure drop _____________________________________________________________________ I-10
2.3 Heat generation due to the pressure drop ______________________________________________ I-13
3 Closed hydraulic circuit (hydrostatic system) __________________________________________ I-15
3.1 Setting up a closed hydraulic circuit ___________________________________________________ I-15
3.2 Hydraulic pumps for closed hydraulic circuits ___________________________________________ I-17
3.2.1 Mechanically resetting the hydraulic pump _____________________________________________ I-17
3.2.2 Hydraulically resetting the hydraulic pump _____________________________________________ I-18
3.3 Feed pumps _______________________________________________________________________ I-20
3.4 Flushing valves ____________________________________________________________________ I-20
3.5 Shock valves ______________________________________________________________________ I-21
4 Load-sensing systems ______________________________________________________________ I-23
4.1 Attributes of load-sensing systems ____________________________________________________ I-23
4.1.1 Open-centre load-sensing systems ____________________________________________________ I-23
4.1.2 Closed centre load-sensing systems ___________________________________________________ I-25
4.2 Energy efficiency of the hydraulic pressure supply _______________________________________ I-30
4.2.1 Loss of energy _____________________________________________________________________ I-30
4.2.2 Pressureless pump recirculation circuit ________________________________________________ I-32
4.2.3 Flow rate control in systems with constant displacement pump ____________________________ I-34
4.2.4 Flow rate control in systems with variable displacement pump _____________________________ I-36
4.2.5 Flow rate control in open-centre load-sensing systems ___________________________________ I-38
4.2.6 Flow rate control in closed centre load-sensing systems __________________________________ I-40
5 Variable-displacement pumps _______________________________________________________ I-42
5.1 Types of variable displacement pumps ________________________________________________ I-42
5.2 Vane pump________________________________________________________________________ I-42
5.3 Axial piston pump __________________________________________________________________ I-44
6 Two-pump system with shut-off valve _________________________________________________ I-46
6.1 Requirements of a pump system for mobile machines ____________________________________ I-46
6.2 Example of a two-pump system with shut-off valve ______________________________________ I-47
7 Flow dividers ______________________________________________________________________ I-48
7.1 Synchronicity of drives ______________________________________________________________ I-48
7.2 Flow divider (50/50 slide valve) ______________________________________________________ I-48
7.3 Rotation flow valve _________________________________________________________________ I-50
7.4 Rotation flow valve for pressure boosting ______________________________________________ I-51
VI © Festo Didactic 574166
8 Valve manifold for mobile hydraulics _________________________________________________ I-49
8.1 Setup of valve blocks _______________________________________________________________ I-53
8.2 Circuit symbol of proportional directional control valves in valve modules ___________________ I-55
8.3 Setup of valve modules _____________________________________________________________ I-56
8.4 Valve slides of proportional directional constant valves ___________________________________ I-57
8.4.1 Design of valve slides _______________________________________________________________ I-57
8.4.2 Influence of control notches on flow rate characteristics __________________________________ I-58
8.5 Input module of a valve manifold _____________________________________________________ I-59
8.5.1 Design of an input module ___________________________________________________________ I-59
8.5.2 Input module in combination with an open-centre valve module ___________________________ I-60
8.5.3 Input module in combination with a closed-centre valve module ___________________________ I-61
8.6 Shock and anti-cavitation valve _______________________________________________________ I-62
9 Circuits with open-centre valves _____________________________________________________ I-64
9.1 Open-centre valves _________________________________________________________________ I-64
9.2 Design of an open-centre 6/3-way valve _______________________________________________ I-66
9.3 Parallel connection _________________________________________________________________ I-69
9.4 Tandem configuration_______________________________________________________________ I-70
9.5 Series connection __________________________________________________________________ I-71
10 Load-independent flow rate control with proportional valves _____________________________ I-72
10.1 Proportional flow control valve _______________________________________________________ I-72
10.2 Upstream pressure balance __________________________________________________________ I-74
10.3 Downstream pressure balance _______________________________________________________ I-78
11 Holding and safe lowering of load ____________________________________________________ I-82
11.1 Application example ________________________________________________________________ I-82
11.2 Piloted non return valve _____________________________________________________________ I-83
11.3 Pressure-relief valve ________________________________________________________________ I-84
11.4 Counterbalancing valve _____________________________________________________________ I-85
12 Hydraulic pilot control ______________________________________________________________ I-88
12.1 Hydraulic pilot control with a joystick __________________________________________________ I-88
13.2 Hydraulic joystick (manually-operated pilot control) _____________________________________ I-88
13.3 Electronic joystick (electro-hydraulic pilot control) _______________________________________ I-90
13 Prioritising consuming devices ______________________________________________________ I-92
13.1 Necessity of prioritising consuming devices ____________________________________________ I-92
13.2 Pressure sequence valve ____________________________________________________________ I-92
13.3 Circuit prioritisation ________________________________________________________________ I-93
13.4 Way valves with prioritisation ________________________________________________________ I-94
13.5 Static prioritity valve ________________________________________________________________ I-94
13.6 Dynamic priority valve ______________________________________________________________ I-95
13.7 3-way flow control valve _____________________________________________________________ I-96
© Festo Didactic 574166 VII
14 Hydrostatic steering _______________________________________________________________ I-98
14.1 Design and characteristics of hydrostatic steering _______________________________________ I-98
14.2 Design of steering valves ____________________________________________________________ I-98
14.2.1 Rotary slide valve and bush __________________________________________________________ I-99
14.2.2 Proportioning pump (Orbitrol pump) _________________________________________________ I-100
14.3 Versions of steering valves _________________________________________________________ I-101
14.3.1 Open-centre steering valves ________________________________________________________ I-101
14.3.2 Closed-centre steering valves _______________________________________________________ I-102
14.3.3 Load-sensing steering valves ________________________________________________________ I-103
14.3.4 Reaction and non-reaction steering valves _____________________________________________ I-103
14.4 Types of steering systems __________________________________________________________ I-104
14.4.1 Ackermann steering system with axle journal steering ___________________________________ I-105
14.4.2 Articulated steering system _________________________________________________________ I-105
Picture credits ___________________________________________________________________________ I-107
© Festo Didactic 574166 VIII
Intended use
The mobile hydraulics basic and advanced level training packages are only to be used:
• for the intended purpose in teaching and training applications
• when their safety functions are in flawless condition
The components in the training packages are designed in accordance with the latest technology as well as
recognised safety rules. However, life and limb of the user and third parties may be endangered, and the
components may be impaired, if they are used incorrectly.
The learning system from Festo Didactic has been developed and produced exclusively for training and
continuing vocational education in the field of automation technology. The training companies and/or
trainers must ensure that all trainees observe the safety instructions described in this workbook.
Festo Didactic hereby excludes all liability for damage suffered by the trainee, the training company and/or
any other third parties as a result of use of these equipment sets outside a purely training situation, unless
Festo Didactic has caused this damage wilfully or through gross negligence.
© Festo Didactic 574166 IX
Preface
Festo Didactic’s training system for automation and technology is geared towards various educational
backgrounds and vocational requirements. The learning system is therefore broken down as follows:
• Technology oriented training packages
• Mechatronics and factory automation
• Process automation and control technology
• Mobile robotics
• Hybrid learning factories
The training system for automation and technology is continuously updated and expanded in accordance
with developments in the field of education, as well as actual professional practice.
The training packages deal with various technologies including pneumatics, electro-pneumatics,
servopneumatics, hydraulics, electro-hydraulics, proportional hydraulics, servohydraulics, mobile
hydraulics, programmable logic controllers, sensor technology, electrical engineering, electronics and
electric drives.
The modular design of the training system allows for applications which go above and beyond the
limitations of the individual training packages. For example, PLC actuation of pneumatic, hydraulic and
electric drives is possible.
X © Festo Didactic 574166
All training packages feature the following elements:
• Hardware
• Media
• Seminars
Hardware
The hardware in the training packages is comprised of industrial components and systems that are specially
designed for training purposes. The components contained in the training packages are specifically
designed and selected for the projects in the accompanying media.
Media
The media provided for the individual topics consist of a mixture of teachware and software. The teachware
includes:
• Technical literature and textbooks (standard works for teaching basic knowledge)
• Workbooks (practical exercises with supplementary instructions and sample solutions)
• Lexicons, manuals and technical books
(which provide technical information on groups of topics for further exploration)
• Transparencies and videos (for easy-to-follow, dynamic instruction)
• Posters (for presenting information in a clear-cut way)
Within the software, the following programmes are available:
• Digital training programmes (learning content specifically designed for virtual training)
• Simulation software
• Visualisation software
• Software for acquiring measurement data
• Project engineering and design engineering software
• Programming software for programmable logic controllers
The teaching and learning media are available in several languages. They are intended for use in classroom
instruction, but are also suitable for self-study.
Seminars
A wide range of seminars covering the contents of the training packages round off the system for training
and vocational education.
Do you have tips, feedback or suggestions for improving this workbook?
If so, please send us an e-mail at did@de.festo.com.
The authors and Festo Didactic look forward to your feedback.
© Festo Didactic 574166 XI
Introduction
This workbook is part of the training system for automation technology from Festo Didactic SE. The system
provides a solid basis for practice oriented training and vocational education. The mobile hydraulics
workbook communicates the basics and fundamental knowledge on the hydraulic systems of mobile work
machines.
The contents of the workbook are project exercises on the basic level of working hydraulics (TP 801),
advanced level steering systems (TP 802) and advanced level working hydraulics (TP 803). The workbook
also contains a basic information section on mobile hydraulics.
The basic level working hydraulics (TP 801) is suitable for basic training in mobile hydraulics.
Using practice-related problem descriptions, the energy balances of different hydraulic systems (also while
loaded) will be examined and evaluated. Control systems with multiple consuming devices are set up in
parallel, tandem and series connections and examined in relation to priority, flow rate distribution, and
pressure dependency. Further course topics are the behaviour of consuming devices while under loads and
the options for safely holding and lowering a load. Basic knowledge of hydraulic device technology is a
prerequisite.
The advanced level steering system (TP 802) communicates the basics of hydrostatic steering systems with
suitable hydraulic controls. The controllers contain typical components of a steering system like steering
valve, shock and anti-cavitation valve, steering cylinder and, if required, a secondary consuming device.
In the project exercises for advanced level working hydraulics (TP 803), details of the working hydraulics are
expanded upon and hydraulic controls with load-sensing controlled variable displacement pump will be set
up and examined.
Technical prerequisites for setting up the controllers include:
• A Learnline or Learntop-S workstation equipped with Festo Didactic slotted profile plates.
• A hydraulic power unit with constant displacement pump (volumetric flow rate: 4 l/min) for TP 801 and
TP 802, a hydraulic power unit with constant displacement pump (volumetric flow rate: 4 l/min) and
load-sensing controlled variable displacement pump for TP 803.
• A power pack with short-circuit protection (input: 230 V, 50 Hz, output: 24 V, max. 5 A).
• Laboratory safety cables
The practical execution of the nine project exercises for TP 801 requires a TP 801 equipment set. One TP 801
and TP 802 equipment set is required for the practical execution of each of the five project exercises for
TP 802. An additional TP 803 equipment set is necessary for the practical execution of the seven project
exercises for TP 803.
The theoretical fundamentals for understanding these exercises can be found in the following textbooks:
• Hydraulics, basic level
• Electro-hydraulics, basic level
as well as in the appendix to this workbook.
Data sheets for the individual components are also available (cylinders, valves, sensors etc.).
XII © Festo Didactic 574166
Work and safety instructions
General
• Trainees should only work with the circuits under the supervision of a trainer.
• Electrical devices (e.g. power supply units, compressors and hydraulic power units) may only be
operated in laboratory rooms which are equipped with residual current devices (RCDs).
• Observe specifications included in the technical data for the individual components, and in particular all
safety instructions!
• Malfunctions which may impair safety must not be generated in the training environment, and must be
eliminated immediately.
• Wear personal safety gear (safety glasses, safety shoes) when working on circuits.
Mechanical system
• Only reach into the setup when it is at a complete standstill.
• Mount all of the components securely onto the slotted profile plate.
• Limit switches may not be actuated frontally.
• Danger of injury during troubleshooting!
Use a tool to actuate the limit switches, for example a screwdriver.
• Set all components up so that activation of switches and disconnectors is not made difficult.
• Adhere to the instructions regarding positioning of the components.
• Always set up cylinders together with the appropriate cover.
Electrical functions
• Use extra-low voltage only (max. 24 V DC).
• Establish or interrupt electrical connections only in the absence of voltage!
• Use only connecting cables with safety plugs for electrical connections.
• When disconnecting connector cables, only pull by the plug, never by the cable.
Hydraulics
• Limit system pressure to 6 MPa (60 bar).
Maximum permissible pressure for all devices included in the training package is 12 MPa (120 bar).
• In the case of double-acting cylinders, pressure could be increased relative to the surface area ratio due
to pressure boosting. With a surface area ratio of 1:1.7 and a system pressure of 6 MPa (60 bar), it may
amount to more than 10 MPa (100 bar).
• Danger of injury due to oil temperatures of greater than 50° C!
Hydraulic fluid with an oil temperature of greater than 50° C may result in burns or scalding.
© Festo Didactic 574166 XIII
• Danger of injury when switching on the hydraulic power unit!
Cylinders may extend and retract automatically.
• Connecting tubing lines
– Never connect or disconnect tubing lines when the hydraulic power unit is running, or while under
pressure!
Couplings must be connected in the unpressurised state.
– Set the coupling socket vertically onto the coupling nipple!
The coupling socket and the coupling nipple must not be fitted askew.
– After each disconnection, make sure that the couplings have closed themselves!
• Hydraulic circuit assembly
– The hydraulic power unit and the electrical power pack
must be switched off when assembling the circuit.
– Before commissioning, make sure that all tank lines have been connected
and that all couplings have been securely fitted.
– Make sure that tubing lines connected to the cylinder are rinsed with hydraulic fluid,
if the volume of oil accommodated by the cylinder is less than the volume which can
be contained by the tubing lines.
• Commissioning
– Cylinders may only be commissioned with their covers in place.
– Switch on the electrical power pack first, and then the hydraulic power unit.
• Dismantling hydraulic circuits
– Assure that pressure has been relived before dismantling the circuit.
– Switch off the hydraulic power unit first, and then the electrical power pack.
• If connections are decoupled while under pressure, pressure is trapped in the device by the non-return
valve in the coupling. This pressure can be vented with the pressure relief unit.
Mounting technology
The mounting boards for the components are equipped with mounting variant A, B or C:
• Variant A, snap-in system
Lightweight devices which cannot be subjected to loads (e.g. directional control valves and sensors).
Simply clip the components into the slots on the slotted profile plate. Release the components from the
slots by actuating the blue lever.
• Variant B, rotary system
Components with medium load capacity (e.g. hydraulic cylinders). These components are clamped to
the slotted profile plate with T-head bolts. The blue knurled nut is used for clamping and loosening.
Make sure that the T-head bolts have been turned 90° after tightening.
• Variant C, screw system
For devices with high load capacity and devices which are seldom removed from the slotted profile plate
(e.g. the hydraulic power unit). These devices are fastened with socket head screws and T-head nuts.
Required accessories
Two digital multimeters are required to evaluate exercises which make use of the flow sensor.
The output voltage of the flow sensor is measured with the multimeter.
XIV © Festo Didactic 574166
Mobile hydraulics training package (TP 800)
The TP 800 training package consists of a multitude of individual training materials. This package refers to
components and basic circuits of the hydraulic systems of working machines. Individual components from
training package TP 800 may also be included in other packages.
Important TP 800 components
• Permanent workstation with Festo Didactic profile plate
• Equipment sets or individual components (e.g. cylinders, valves and pressure gauges)
• Complete set of laboratory equipment
Media
The teachware for the training package TP 800 consists of one workbook. The contents of the workbook are
the project exercises on the basic level of working hydraulics (TP 801), advanced level steering systems
(TP 802) and advanced level working hydraulics (TP 803). The theoretical fundamentals for understanding
the exercises are described in the textbook attachment.
The workbook includes the exercise sheets and worksheets for the project exercise, the solutions to each
individual worksheet and a CD-ROM. A set of ready-to-use exercise sheets and worksheets is included in
each workbook for all of the exercises.
Data sheets for the hardware components are made available along with the equipment set.
Media
Textbooks Fundamentals of hydraulics and electrohydraulics
Workbooks Mobile hydraulics (TP 800)
Set of posters Hydraulics
Simulation programme FluidSIM® Hydraulic
TP 810 Diagnostic system FluidLab® M
Digital training programme Web-based training, hydraulics – Basics of hydraulics principles
Web-based training electro-hydraulices – Basics of electro-hydraulics principles
Overview of media for training package TP 800
The media are offered in several languages. Further training materials can be found in our catalogues and on
the Internet.
© Festo Didactic 574166 XV
Learning objectives
Mobile hydraulics: Basic level working hydraulics (TP 801)
• To know the relationship between pressure, flow rate and power output.
• To be able to calculate the power consumption of a hydraulic system.
• To know that flow division can lead to energy losses in a hydraulic system.
• To know that when using a constant displacement pump, non-decreasing volume flow leads to energy
loss.
• To know how a constant displacement pump with an open-centre load-sensing pressure balance works.
• To know the power-relevant advantages of a constant displacement pump with pressure regulation by
an open-centre load-sensing pressure balance over a constant displacement pump without an open-
centre load-sensing pressure balance.
• To be familiar with the mode of operation of a 6/3-way proportional valve.
• To know that proportional directional control valves restrict inflow and outflow.
• To know that a 6/3-way proportional valve with mid-position tank recirculation only generates minor
energy loss in mid-position.
• To know how a shuttle valve works and how to use it.
• To understand the control circuit of an open-centre load-sensing system.
• To know that a proportional directional control valve in connection with an open-centre load-sensing
pressure balance represents a flow control valve.
• To be able to use the cylinder load simulator (loading unit).
• To understand the behaviour of the cylinders under load.
• To know how to use a delockable double non-return valve for the purpose of secure holding.
• To know the advantages and disadvantages of a delockable double non-return valve.
• To be able to use a pressure-relief valve as a counter-pressure valve for secure holding and lowering.
• To know the advantages and disadvantages of counter-pressure valves.
• To be able to use a counterbalancing valve for the secure holding and lowering of a load.
• To know the main difference between a counterbalancing valve and a pressure-relief valve.
• To know that using a counterbalancing valve can reduce energy when lowering a load.
• To know how series, parallel and tandem configurations of 6/3-way proportional valves work.
• To be able to describe the advantages and disadvantages of these configuration types for an
application.
XVI © Festo Didactic 574166
Mobile hydraulics: Advanced level steering system (TP 802)
• To understand how the steering valve works.
• To know the properties of a non-reaction steering valve.
• To understand the behaviour of the steering system under the influence of external forces.
• To explain how a shock valve works.
• To know for which applications shock valves are to be used.
• To understand why it is necessary that one drive in a hydraulic system with multiple drives must
preferably be supplied by oil (priority function).
• To know the effects of the priority function.
• To know the setup of a centre-pivot steering.
Mobile hydraulics: Advanced level working hydraulics (TP 803)
• To be able to explain the load-sensing function of valve manifolds.
• To understand how the load-dependent pump pressure regulation (load-sensing) works.
• To know the power-relevant advantages of hydraulic systems with load-sensing-controlled variable
displacement pumps.
• To know how valve manifolds in mobile hydraulics work and how to use them.
• To know the properties of a hydraulic joystick.
• To be able to control proportional directional control valves with a hydraulic joystick.
• To know the relationship between load changes and speed changes when using a flow control valve.
• To know the properties of a 2-way flow control valve.
• To know how to maintain a constant speed despite changing loads.
• To be able to regulate flow rate with a load-sensing controlled pump unit.
• To know the limits of a load-sensing system.
• To understand the advantages and disadvantages of the upstream pressure balance in load-sensing
systems.
• To be familiar with the mode of operation of the downstream pressure balance.
• To know the advantages and disadvantages of the downstream pressure balance in load-sensing
systems.
© Festo Didactic 574166 XVII
Allocation of learning objectives to exercises
Mobile hydraulics: Basic level working hydraulics (TP 801)
Exercise 1-1 1-2 1-3 1-4 1-5 1-6 1-7 1-8 1-9
Learning objective
To know the relationship between pressure, flow rate and power
output. •
To be able to calculate the power consumption of a hydraulic
system. •
To know that flow division can lead to energy losses in a hydraulic
system. •
To know that when using a constant displacement pump, non-
decreasing volume flow leads to energy loss. •
To know how a constant displacement pump with an open-centre
load-sensing pressure balance works. •
To know the power-relevant advantages of a constant
displacement pump with pressure regulation by an open-centre
load-sensing pressure balance over a constant displacement
pump without an open-centre load-sensing pressure balance.
•
To be familiar with the mode of operation of a 6/3-way
proportional valve. •
To know that proportional directional control valves restrict inflow
and outflow. •
To know that a 6/3-way proportional valve with mid-position tank
recirculation only generates minor energy loss in mid-position. •
To know how a shuttle valve works and how to use it. •
To understand the control circuit of an open-centre load-sensing
system. •
To know that a proportional directional control valve in
connection with an open-centre load-sensing pressure balance
represents a flow control valve.
•
To be able to use the cylinder load simulator (loading unit). •
To understand the behaviour of the cylinders under load. •
To know how to use a delockable double non-return valve for the
purpose of secure holding. •
To know the advantages and disadvantages of a delockable
double non-return valve. •
XVIII © Festo Didactic 574166
Exercise 1-1 1-2 1-3 1-4 1-5 1-6 1-7 1-8 1-9
Learning objective
To be able to use a pressure-relief valve as a counter-pressure
valve for secure holding and lowering. •
To know the advantages and disadvantages of counter-pressure
valves. •
To be able to use a counterbalancing valve for the secure holding
and lowering of a load. •
To know the main difference between a counterbalancing valve
and a pressure-relief valve. •
To know that using a counterbalancing valve can reduce energy
when lowering a load. •
To know how series, parallel and tandem configurations of 6/3-
way proportional valves work. •
To be able to describe the advantages and disadvantages of these
configuration types for an application. •
Mobile hydraulics: Advanced level steering system (TP 802)
Exercise 2-1 2-2 2-3 2-4 2-5
Learning objective
To understand how the steering valve works. •
To know the properties of a non-reaction steering valve. •
To understand the behaviour of the steering system under the influence of external
forces. •
To explain how a shock valve works. •
To know for which applications shock valves are to be used. •
To understand why it is necessary that one drive in a hydraulic system with multiple
drives must preferably be supplied by oil (priority function). •
To know the effects of the priority function. •
To know the setup of a centre-pivot steering. •
© Festo Didactic 574166 XIX
Mobile hydraulics: Advanced level working hydraulics (TP 803)
Exercise 3-1 3-2 3-3 3-4 3-5 3-6 3-7
Learning objective
To be able to explain the load-sensing function of valve manifolds. •
To understand how the load-dependent pump pressure regulation (load-
sensing) works. •
To know the power-relevant advantages of hydraulic systems with load-
sensing-controlled variable displacement pumps. •
To know how valve manifolds in mobile hydraulics work and how to use
them. •
To know the properties of a hydraulic joystick. •
To be able to control proportional directional control valves with a
hydraulic joystick. •
To know the relationship between load changes and speed changes when
using a flow control valve. •
To know the properties of a 2-way flow control valve. •
To know how to maintain a constant speed despite changing loads. •
To be able to regulate flow rate with a load-sensing controlled pump unit. •
To know the limits of a load-sensing system. •
To understand the advantages and disadvantages of the upstream
pressure balance in load-sensing systems. •
To be familiar with the mode of operation of the downstream pressure
balance. •
To know the advantages and disadvantages of the downstream pressure
balance in load-sensing systems. •
XX © Festo Didactic 574166
Equipment set
The equipment sets TP 801, TP 802 and TP 803 are compiled for the basic and advanced level mobile
hydraulics. Equipment set TP 801 includes all of the components which are necessary for mastering the
learning objectives for TP 801. To master the learning objectives for TP 802, you will require the components
of the three equipment sets TP 801 and TP 802. For the setup of the control units for TP 803, you will require
the components of the three equipment sets TP 801, TP 802 and TP 803. The equipment sets can be
supplemented with other equipment sets as desired.
Equipment set: Mobile hydraulics, basic level working hydraulics (TP 801), order no. 574161
Designation Order number Quantity
6/3-way proportional hand lever valve, mid-position with tank recirculation 572141 2
3-way pressure regulator 544337 1
Shut-off valve 152844 1
Double non-return valve, delockable 572151 1
Flow control valve 152842 1
Pressure-relief valve 544335 2
Pressure balance for open-centre load-sensing 572123 1
Electronic pressure switch 548612 2
Flow sensor 567191 2
Hydraulic motor 152858 2
Diaphragm accumulator with shut-off block 152859 1
Non-return valve, opening pressure: 0.6 MPa 548618 1
Delockable counter balance valve (overcentre valve) 572149 1
T-distributor 152847 3
4-way manifold plate with pressure gauge 159395 2
Shuttle valve 572122 1
Cylinder load simulator (loading unit) 572145 1
© Festo Didactic 574166 XXI
Graphic symbols, equipment set
Component Graphic symbol
6/3-way proportional hand lever valve,
mid-position with tank recirculation
T2P1P2
BT1A
3-way pressure regulator
T
A
P
Shut-off valve
Double non-return valve,
delockable
B1A1
B2A2
Flow control valve A B
Pressure-relief valve P
T
Pressure balance for open-centre
load-sensing
XT
P0.55 MPa
P
TX
0.55 MPa
XXII © Festo Didactic 574166
Component Graphic symbol
Electronic pressure switch ISO 1219-1 EN 60617-7
p
2
RD (1)BK1 (4),BK2 (5),
WH (2)
BU (3)
p
U
SP1SP2
Flow sensor ISO 1219-1 EN 60617-7
0V (BU)
q
24V (RD)
0 – 10V(BK)
Hydraulic motor
Diaphragm accumulator with shutoff block
1 0 2
TP
Non-return valve, opening pressure:
0.6 MPa
Delockable counter balance valve
(overcentre valve)
X (1:3)
P
T
T-distributor
© Festo Didactic 574166 XXIII
Component Graphic symbol
4-way manifold plate,
with pressure gauge
Shuttle valve B
A2A1
Cylinder load simulator
(loading unit)
A1.2A1.1 A2.1 A2.2
Equipment set: Mobile hydraulics, advanced level steering system (TP 802), order no. 574162
Designation Order number Quantity
4/3-way hand lever valve, working lines relieved in mid-position, detenting 544344 1
Steering valve (Orbitrol) 572146 1
Shock and replenishing manifold 572148 1
4-way return header, unpressurised 573026 1
Tubing line for unpressurised return 573024 1
XXIV © Festo Didactic 574166
Graphic symbols, equipment set
Component Graphic symbol
4/3-way hand lever valve, working lines
relieved in mid-position, detenting
BA
TP
Steering valve (Orbitrol) L R
P ET
Shock and replenishing manifold
T B1
B2
A1
A2
4-way return header, unpressurised
Tubing line for unpressurised return
© Festo Didactic 574166 XXV
Equipment set: Mobile hydraulics, advanced level working hydraulics (TP 803), order no. 5741632
Designation Order number Quantity
Flow control valve 152842 2
Pressure balance, downstream 572741 2
Pressure balance, upstream 573023 1
Load-sensing control block 572144 1
Tubing line for unpressurised return 573024 1
T-distributor 152847 1
Pilot controller (joystick), 2x2-channel 572147 1
Graphic symbols, equipment set
Component Graphic symbol
Flow control valve A B
Pressure balance, downstream
XA
P
35 kPa
A
P
X
35 kPa
Pressure balance, upstream
XP
A
0.55 MPa
A
PX
0.55 MPa
Load-sensing control block
TP
D (X1.2) A1 B1
LS
D (X2.2) A2 B2
XXVI © Festo Didactic 574166
Component Graphic symbol
Tubing line for unpressurised return
T-distributor
Pilot controller (joystick),
2x2-channel
X1.1
TP
X1.2 X2.1 X2.2
© Festo Didactic 574166 XXVII
Allocation of components to exercises
Equipment set: Mobile hydraulics, basic level working hydraulics (TP 801)
Exercise 1-1 1-2 1-3 1-4 1-5 1-6 1-7 1-8 1-9
Component
6/3-way proportional hand lever valve, mid-position with tank
recirculation 1 1 1 1 1 1 2
3-way pressure regulator 1 1 1 1
Shut-off valve 1 1 1 1 1 1 1 1 1
Double non-return valve, delockable 1
Flow control valve 1 1 1
Pressure-relief valve 2 1 2 2 1 2
Pressure gauge 1 1
Pressure balance for open-centre load-sensing 1 1
Electronic pressure switch 2 2 2 2 2 2 2 2 2
Flow sensor 2 2 2 2 1 1 1 2
Hydraulic motor 2 2 2 2 1 1 1 2
Diaphragm accumulator with shutoff block 1 1 1 1
Non-return valve, opening pressure: 0.6 MPa 1 1 1 1
Delockable counter balance valve (overcentre valve) 1
T-distributor 1 2 1 2 2 3 2
4-way manifold plate with pressure gauge 2 2 2 2 2 2 2 2 2
Shuttle valve 1
Cylinder load simulator (loading unit) 1 1 1 1
Required accessories
Exercise 1-1 1-2 1-3 1-4 1-5 1-6 1-7 1-8 1-9
Component
Digital multimeter 2 2 2 2 1 1 1 2
Hydraulic power unit with constant displacement pump
(volumetric flow rate: 4 l/min) 1 1 1 1 1 1 1 1 1
Power pack, 24 V DC 1 1 1 1 1 1 1 1 1
Tubing line 9 10 13 15 12 15 16 16 16
XXVIII © Festo Didactic 574166
Mobile hydraulics equipment set: Advanced level steering system (TP 802)
Exercise 2-1 2-2 2-3 2-4 2-5
Component
4/3-way hand lever valve, working lines relieved in mid-position, detenting 1 1 1
Steering valve (Orbitrol) 1 1 1 1 1
Shock and replenishing manifold 1
4-way return header, unpressurised 1 1 1 1
Tubing line for unpressurised return 1 1 1 1 1
3-way pressure regulator 1 1 1
Shut-off valve 1 1 1 1 1
Pressure gauge 1 1 1
Electronic pressure switch 2 2 2 2
Flow sensor 1
Hydraulic motor 1
Diaphragm accumulator with shutoff block 1 1 1
Non-return valve, opening pressure: 0.6 MPa 1 1 1
Delockable counter balance valve (overcentre valve) 2
T-distributor 1 2 2
4-way manifold plate with pressure gauge 2 2 2 2 2
Cylinder load simulator (loading unit) 1 1 1 1 1
* Components with grey background come from equipment set TP 801.
Required accessories
Exercise 2-1 2-2 2-3 2-4 2-5
Component
Digital multimeter 1
Hydraulic power unit with constant displacement pump
(volumetric flow rate: 4 l/min) 1 1 1 1 1
Power pack, 24 V DC 1 1 1 1
Tubing line 8 13 16 15 9
© Festo Didactic 574166 XXIX
Mobile hydraulics equipment set: Advanced level working hydraulics (TP 803)
Exercise 3-1 3-2 3-3 3-4 3-5 3-6 3-7
Component
Flow control valve 1 1 2
Pressure balance, downstream 2
Pressure balance, upstream 1 1
Load-sensing control block 1 1 1 1
Tubing line for unpressurised return 1
T-distributor 1
Pilot controller (joystick), 2x2-channel 1
4-way return header, unpressurised 1
Tubing line for unpressurised return 1 1 1 1
Shut-off valve 1
Flow control valve 1 1 1 1
Pressure-relief valve 1 2 2 2
Pressure gauge 1 1
Electronic pressure switch 2 2 2 2 2 2 2
Flow sensor 1 1 2 2 2
Hydraulic motor 1 1 1 2 2
T-distributor 1 2 3 3
4-way manifold plate with pressure gauge 2 2 2 2 2 2 2
Shuttle valve 1 1
Cylinder load simulator (loading unit) 1 1
*) Components with light grey background are components from the equipment set TP 802
**) Components with dark grey background are components from the equipment set TP 801
Required accessories
Exercise 3-1 3-2 3-3 3-4 3-5 3-6 3-7
Component
Digital multimeter 1 1 2 2 2
Hydraulic power unit with a constant displacement pump (volumetric flow
rate: 4 l/min) and load-sensing-controlled variable displacement pump 1 1 1 1 1 1 1
Power pack, 24 V DC 1 1 1 1 1 1 1
Tubing line 10 10 9 8 9 15 16
XXX © Festo Didactic 574166
Notes for the teacher/trainer
Learning objectives
The basic learning objective of this workbook is to understand, set up, safely commission and analyse using
measurement technology the basic hydraulic circuits of mobile work machines. This knowledge is gained by
means of theoretical questions and by actually setting up the circuits on the slotted profile plate. Direct
interplay of theory and practice ensures fast progress and long-lasting learning. The more specific learning
objectives are documented in the matrix. Concrete, individual learning objectives are assigned to each
exercise.
Required time
The time required for working through the exercises depends on the learner’s previous knowledge of the
subject matter. Each exercise should take approximately 1 to 1½ hours.
Components of the equipment sets
The project exercises of the workbook and associated equipment sets TP 801, TP 802 and TP 803 are
coordinated with each other. For the nine exercises of basic level working hydraulics (TP 801), you will
require the components of a TP 801 equipment set. For the five exercises of the advanced level steering
system (TP 802), you will require the components of each of the TP 801 and TP 802 equipment sets. For the
seven exercises of advanced level working hydraulics (TP 803), you will require the components of the three
equipment sets TP 801, TP 802 and TP 803.
Standards
The following standards are applied in this workbook:
ISO 1219-1 Fluid power systems and components – Graphic symbols and
circuit diagrams
EN 60617-2 to EN 60617-8 Graphic symbols for diagrams
EN 81346-2 Industrial systems, installations and equipment and industrial products;
structuring principles and reference designations
Identification in the workbook
Solutions and supplements in graphics or diagrams appear in red.
Components used to simulate the load for the application have grey backgrounds in the circuit diagram.
Classifications in the set of exercises
Texts which require completion are identified with a grid or grey table cells.
Graphics and diagrams which require completion include a grid.
Notes for the lesson
Additional information is provided here regarding the didactic-methodological procedure, the individual
components and the completed controllers. These notes are not included in the set of exercises.
© Festo Didactic 574166 XXXI
Solutions
The solutions specified in this workbook result from test measurements. The results of your measurements
may deviate from these.
Structure of the exercises
All of the project exercises of the basic level TP 801 and the two advanced levels TP 802 and TP 803 have the
same methodical structure. The tasks and are broken down into:
• Title
• Learning objectives
• Problem description
• Positional sketch
• Project assignments
• Work aids
• Worksheets
The workbook includes the solutions for all of the worksheets for all exercises.
Component designations
Components are designated in circuit diagrams in accordance with DIN ISO 1219-2. All of the components
included in any given circuit have the same primary identifying number. Letters are assigned depending on
each respective type of component. Consecutive numbers are assigned if several components of the same
type are included within a single circuit.
Cylinders: 1A1, 2A1, 2A2 ...
Valves: 1V1, 1V2, 1V3, 2V1, 2V2, 3V1 …
Sensors: 1B1, 1B2 ...
Signal input: S1, S2 …
Accessories: 0Z1, 0Z2, 1Z1 …
CD-ROM contents
The workbook is included on the CD-ROM as a PDF file. The CD-ROM also provides you with additional
media.
The CD-ROM contains the following folders:
• Data sheets
• Illustrations
• Operating instructions
XXXII © Festo Didactic 574166
Data sheets
The data sheets for the components included in the training package are supplied along with the equipment
set, and are additionally available as PDF files.
Illustrations
Photos and graphics of components and industrial applications are made available. These can be used to
illustrate individual tasks or to supplement project presentations.
Operating instructions
Operating instructions are provided for various components included in the training package. These
instructions are helpful when using and commissioning the components.
© Festo Didactic 574166 1
Contents
Exercises and solutions: Mobile hydraulics, basic level working hydraulics (TP 801)
Exercise 1-1: Examining performance for a controller using constant displacement pump
and fixed pressure limitation _____________________________________________________ 3
Exercise 1-2: Examining performance for a controller using constant displacement pump
and adjusted pressure limitation using open-centre load-sensing pressure balance ______ 13
Exercise 1-3: Examining performance of speed control using a 6/3-way proportional valve ____________ 23
Exercise 1-4: Examining energy efficiency of speed control in an open-centre load-sensing system _____ 31
Exercise 1-5: Moving and holding a load with a 6/3-way proportional valve _________________________ 41
Exercise 1-6: Moving and holding a load with a piloted non-return valve ___________________________ 51
Exercise 1-7: Moving and holding a load with a pressure-relief valve as counter pressure _____________ 59
Exercise 1-8: Moving and holding a load with a counterbalancing valve ____________________________ 69
Exercise 1-9: Examining parallel, series and tandem configurations _______________________________ 79
2 © Festo Didactic 574166
© Festo Didactic 574166 3
Exercise 1-1: Examining performance for a controller using constant displacement pump
and fixed pressure limitation
Learning objectives
After completing this exercise:
• you will be familiar with the relationship between pressure, flow rate and power output.
• you will be able to calculate the power consumption of a hydraulic system.
• you will know that flow division can lead to energy losses in a hydraulic system.
• you will know that when using a constant displacement pump, non-decreasing volume flow leads to
energy loss.
Problem description
The motor speed of a wheel milling cutter is controlled using a flow control valve. The rotation of the motor
is only in one direction. The load acting on the motor changes depending on the soil conditions.
Examine how different load requirements affect the energy balance of the controls.
Positional sketch
Wheel saw, © Bobcat, www.bobcat.eu
Exercise 1-1 – Examining performance for a controller using constant displacement pump and fixed pressure limitation
4 © Festo Didactic 574166
Parameters
• When the hydraulic power unit is switched on, the motor will turn.
• The load on the motor should be simulated using a proportional pressure-relief valve.
Project assignments
1. Set up the controller.
2. Familiarise yourself with the commissioning procedure.
3. Find out about the procedure when taking measurements in the electrical circuit.
4. Double check the controller configuration.
5. Measure the pressure and flow rate at different load pressures.
6. Calculate the power output of the pump unit; the effective power and the power loss based on the
measured values. Depict the calculated power output in the bar chart and evaluate the results.
Visual inspection
Continuous visual inspection for defects in tubing and hydraulic devices is an essential part of
hydraulic safety standards.
Work aids
• Data sheets, operating instructions
• Hydraulics textbook
• Basics of mobile hydraulics (see attachment)
Exercise 1-1 – Examining performance for a controller using constant displacement pump and fixed pressure limitation
© Festo Didactic 574166 5
1. Setting up the controller
1B3
0Z1
1V1
p2
1V3
1B4
45 bar
P2LS T T L L LA LAP1
60 bar
P
Tp1
1V4
1V2
P
Tq2
n
1B21A1
n
1B1
q1
A
B
Circuit diagram
Note for the lesson
The shut-off valve is used for switching pump recirculation. This type of commissioning circuit is
used for all of the exercises below as well.
Electronic pressure switches are used to display precise pressure values.
If the hydraulic motor is only used in connection with a flow sensor, the combination of the two will
be given the equipment designation B for a sensor. If the hydraulic motor is an independent driving
component of the control system, it will be given its own designation A (also only in connection with
a flow sensor).
Note
The pressure-relief valve 1V4 is used to set load pressures.
Exercise 1-1 – Examining performance for a controller using constant displacement pump and fixed pressure limitation
6 © Festo Didactic 574166
Quantity Labelling Designation
2 1B3, 1B4 Electronic pressure switch
2 1B1, 1B2 Flow sensor, coupled with hydraulic motor
1 1A1 Hydraulic motor
1 1V3 Flow control valve
2 1V1, 1V4 Pressure-relief valve
1 1V2 Shut-off valve
2 — 4-way manifold plate with pressure gauge
9 — Tubing line
1 0Z1 Hydraulic power unit with constant displacement pump
Equipment list
Note
You will need the following in order to perform the measurements.
• 1 power pack 24 V DC
• 2 digital multimeters
– Set up the controller.
Observe the following points when setting up the controller:
• Set the pressure-relief valve for the constant displacement pump of the hydraulic power unit to a
pressure of 60 bar (6 MPa) before setting up the control.
• Use the circuit diagram.
• Designate the components.
• Connecting tubing lines
– Never connect or disconnect tubing lines when the hydraulic power unit is running, or while under
pressure!
Couplings must be connected in the unpressurised state.
– Set the coupling socket vertically onto the coupling nipple!
The coupling socket and the coupling nipple must not be fitted askew.
• Selecting and laying tubing lines
– Select the tubing line length such that adequate leeway is available
in order to accommodate changes in length which result from pressure.
– Avoid mechanical stressing of the tubing line.
– Do not bend the tubing line into a radius of less than its specified minimum bending radius
of 51 mm.
– Do not twist the tubing line during installation.
– Make sure that tubing lines do not become kinked.
• Mark the completed tubing connections in the hydraulic circuit diagram.
Exercise 1-1 – Examining performance for a controller using constant displacement pump and fixed pressure limitation
© Festo Didactic 574166 7
2. Becoming familiar with the commissioning procedure
Information
During practice operation and for industrial maintenance purposes, safe commissioning is
undertaken at low pressure which is then increased up to the maximum value. This is possible with
either a pressure-relief valve or a pump recirculation circuit. At low pressure, leaks can be safely
detected after device replacement, for example.
Commissioning procedure with pump recirculation circuit
1. Switch to pump recirculation by opening the shut-off valve.
2. With electro-hydraulic controls, activate the electrical 24 V DC control voltage.
3. Switch the hydraulic pump on.
4. Slowly close the shut-off valve until a circulating pressure of approximately 15 bar prevails.
Immediately set the pump back to recirculation in the event of leaks.
5. Run the sequence once and watch for leaks.
6. Fully close the shut-off valve and set the pressure limit at the pressure-relief valve of the
hydraulic power unit to the specified value.
3. Finding out about the procedure when taking measurements in the electrical circuit
Safety instructions
• Before measuring, make sure that the section of the controller in which you intend to take
measurements only works with an electrical voltage of no greater than 24 V DC!
• Measurements within sections of the controller which function with higher voltages (e.g. 230 V)
may only be performed by persons who have received appropriate training or instruction.
• Incorrect performance of this measurement is life endangering!
• Observe the safety precautions for working with electrical power!
Exercise 1-1 – Examining performance for a controller using constant displacement pump and fixed pressure limitation
8 © Festo Didactic 574166
Information
Procedure for performing measurements in the electrical circuit
1. Switch off supply power to the electrical circuit.
2. Select the desired operating mode at the multimeter (e.g. direct current measurement).
3. Connect the measuring instrument with correct polarity when measuring direct current/
direct voltage.
4. Select the largest measuring range.
5. Switch supply power to the electrical circuit back on.
6. Watch the display and switch to increasingly smaller measuring ranges step-by-step.
7. Read the value from the display after arriving at the smallest possible measuring range.
4. Double checking the controller setup
Observe the following points when commissioning the controller:
• Before commissioning, make sure that all tank lines have been connected and that all couplings have
been securely fitted.
• Fully close the flow control valve 1V3.
• Fully open both pressure-relief valves 1V1 and 1V4.
• Switch to pump recirculation by opening shut-off valve 1V2.
• Switch off the 24 V DC electrical supply voltage for the flow sensors and pressure switches.
Note
You will find information on the sensors in the operating instructions.
When using the analogue output of the pressure switch, make sure it is set to between 0-10 V.
• Switch the hydraulic power unit on.
• Slowly close the shut-off valve 1V2. The entire pump unit delivery rate flows at low pressure through the
pressure-relief valve 1V1 to the tank.
Immediately set the pump back to recirculation in the event of leaks.
• Set the pressure at the pressure-relief valve 1V1 to 45 bar.
• Perform the measurement tasks.
5. Measuring pressure and flow rate at different load pressures
Execution
Set the pressure-relief valve 1V1 to 45 bar. Set the values indicated in the table for the flow control
valve 1V3 and the pressure-relief valve 1V4. Measure the pressure and flow rate for these values.
Exercise 1-1 – Examining performance for a controller using constant displacement pump and fixed pressure limitation
© Festo Didactic 574166 9
– Set the values indicated in the table. Enter the measured pressure and flow rate values into the table.
Load case Valve specifications Pump pressure p1 [bar]
Flow rate q1 [l/min]
Load pressure p2 [bar]
Flow rate q2 [l/min]
a 1V3: open
1V4: Minimum pressure 15.8 4.14 12.4 4.22
b 1V3: open 33 4.1 30 4.18
c 1V4: Minimum pressure 43.8 4.06 3.2 0.5
d — 43.6 4.06 30 0.5
e — 40.6 4.06 25 2
f — 45 4.06 1 0
Measurement log
Notes
Fully open the flow control valve 1V3 before dismantling the controller.
Fully open the pressure-relief valves 1V1 and 1V4 before dismantling.
6. Calculating the pumping power, effective power and power loss
Information
The formula for calculating the power in the hydraulic system when using the indicated physical
units is:
600q pP ⋅
=
P Power [kW]
q Flow rate [l/min]
p Pressure [bar]
Power output of the pump unit: PP
1 1P 600
q pP
⋅=
PP Power output of the pump unit [kW]:
q1 Flow volume of the pump unit [l/min]
p1 Pump pressure [bar]
Exercise 1-1 – Examining performance for a controller using constant displacement pump and fixed pressure limitation
10 © Festo Didactic 574166
Effective power (output of the consuming device): PL
2 2L 600
q pP
⋅=
PL Output of the consuming device [kW]
q2 Flow rate to the consuming device [l/min]
p2 Load pressure [bar]
Power loss: PV
V P LP P P= −
PV Power loss [kW]
a) Calculate the pumping power, effective power and power loss for the load cases a to f (see workbook 4).
Enter the values to the table.
Load case Pumping power
PP [kW]
Effective power
PL [kW]
Power loss
PV [kW]
a 0.109 0.087 0.022
b 0.226 0.209 0.017
c 0.296 0.003 0.293
d 0.295 0.025 0.27
e 0.275 0.083 0.192
f 0.305 0 0.305
Performance for the load cases a to f
Exercise 1-1 – Examining performance for a controller using constant displacement pump and fixed pressure limitation
© Festo Didactic 574166 11
b) Transfer the performance values for load cases a to f to a bar chart.
PP Pumping power
PL Effective power
PV Power loss
Performance of the system with constant displacement pump and pressure limitation with different load cases a to f
c) When is power loss PV particularly high? Give reasons for your answer.
Power loss (PV) is particularly high when the flow rate of the consuming device (q2) is low. In this case,
almost the entire delivery rate of the pump unit must discharge at maximum pressure through the
pressure-relief valve.
Exercise 1-1 – Examining performance for a controller using constant displacement pump and fixed pressure limitation
12 © Festo Didactic 574166
© Festo Didactic 574166 1
Contents
Exercises and worksheets: Mobile hydraulics, basic level working hydraulics (TP 801)
Exercise 1-1: Examining performance for a controller using constant displacement pump
and fixed pressure limitation _____________________________________________________ 3
Exercise 1-2: Examining performance for a controller using constant displacement pump
and adjusted pressure limitation using open-centre load-sensing pressure balance ______ 13
Exercise 1-3: Examining performance of speed control using a 6/3-way proportional valve ____________ 23
Exercise 1-4: Examining energy efficiency of speed control in an open-centre load-sensing system _____ 31
Exercise 1-5: Moving and holding a load with a 6/3-way proportional valve ________________________ 41
Exercise 1-6: Moving and holding a load with a piloted non-return valve ___________________________ 51
Exercise 1-7: Moving and holding a load with a pressure-relief valve as counter pressure _____________ 59
Exercise 1-8: Moving and holding a load with a counterbalancing valve ____________________________ 69
Exercise 1-9: Examining parallel, series and tandem configurations _______________________________ 79
Exercises and worksheets: Mobile hydraulics, advanced level steering system (TP 802)
Exercise 2-1: Examining the steering valve in a hydrostatic steering system ________________________ 91
Exercise 2-2: Examining steering when external forces are exerted ________________________________ 99
Exercise 2-3: Examining overload protection for steering _______________________________________ 107
Exercise 2-4: Examining a steering system with priority function _________________________________ 115
Exercise 2-5: Designing a steering system for centre-pivot steering ______________________________ 123
Exercises and worksheets: Mobile hydraulics, advanced level working hydraulics (TP 803)
Exercise 3-1: Examining a hydraulic system with load-sensing-controlled variable displacement pump _ 133
Exercise 3-2: Examining the load hold function _______________________________________________ 143
Exercise 3-3: Remotely controlling proportional directional control valves using a hydraulic joystick ___ 151
Exercise 3-4: Setting a (volumetric) flow rate independent of load _______________________________ 159
Exercise 3-5: Setting the volumetric flow rate using a load-sensing-controlled pump unit ____________ 169
Exercise 3-6: Examining a load-sensing system with upstream pressure balance ___________________ 179
Exercise 3-7: Examining a load-sensing system with downstream pressure balance _________________ 191
2 © Festo Didactic 574166
© Festo Didactic 574166 3
Exercise 1-1: Examining performance for a controller using constant displacement pump
and fixed pressure limitation
Learning objectives
After completing this exercise:
• you will be familiar with the relationship between pressure, flow rate and power output.
• you will be able to calculate the power consumption of a hydraulic system.
• you will know that flow division can lead to energy losses in a hydraulic system.
• you will know that when using a constant displacement pump, non-decreasing volume flow leads to
energy loss.
Problem description
The motor speed of a wheel milling cutter is controlled using a flow control valve. The rotation of the motor
is only in one direction. The load acting on the motor changes depending on the soil conditions.
Examine how different load requirements affect the energy balance of the controls.
Positional sketch
Wheel saw, © Bobcat, www.bobcat.eu
Exercise 1-1 – Examining performance for a controller using constant displacement pump and fixed pressure limitation
4 Name: __________________________________ Date: ____________ © Festo Didactic 574166
Parameters
• When the hydraulic power unit is switched on, the motor will turn.
• The load on the motor should be simulated using a proportional pressure-relief valve.
Project assignments
1. Set up the controller.
2. Familiarise yourself with the commissioning procedure.
3. Find out about the procedure when taking measurements in the electrical circuit.
4. Double check the controller configuration.
5. Measure the pressure and flow rate at different load pressures.
6. Calculate the power output of the pump unit; the effective power and the power loss based on the
measured values. Depict the calculated power output in the bar chart and evaluate the results.
Visual inspection
Continuous visual inspection for defects in tubing and hydraulic devices is an essential part of
hydraulic safety standards.
Work aids
• Data sheets, operating instructions
• Hydraulics textbook
• Basics of mobile hydraulics (see attachment)
Exercise 1-1 – Examining performance for a controller using constant displacement pump and fixed pressure limitation
© Festo Didactic 574166 Name: __________________________________ Date: ____________ 5
1. Setting up the controller
1B3
0Z1
1V1
p2
1V3
1B4
45 bar
P2LS T T L L LA LAP1
60 bar
P
Tp1
1V4
1V2
P
Tq2
n
1B21A1
n
1B1
q1
A
B
Circuit diagram
Note
The pressure-relief valve 1V4 is used to set load pressures.
Exercise 1-1 – Examining performance for a controller using constant displacement pump and fixed pressure limitation
6 Name: __________________________________ Date: ____________ © Festo Didactic 574166
Quantity Labelling Designation
2 1B3, 1B4 Electronic pressure switch
2 1B1, 1B2 Flow sensor, coupled with hydraulic motor
1 1A1 Hydraulic motor
1 1V3 Flow control valve
2 1V1, 1V4 Pressure-relief valve
1 1V2 Shut-off valve
2 — 4-way manifold plate with pressure gauge
9 — Tubing line
1 0Z1 Hydraulic power unit with constant displacement pump
Equipment list
Note
You will need the following in order to perform the measurements.
• 1 power pack 24 V DC
• 2 digital multimeters
– Set up the controller.
Observe the following points when setting up the controller:
• Set the pressure-relief valve for the constant displacement pump of the hydraulic power unit to a
pressure of 60 bar (6 MPa) before setting up the control.
• Use the circuit diagram.
• Designate the components.
• Connecting tubing lines
– Never connect or disconnect tubing lines when the hydraulic power unit is running, or while under
pressure!
Couplings must be connected in the unpressurised state.
– Set the coupling socket vertically onto the coupling nipple!
The coupling socket and the coupling nipple must not be fitted askew.
• Selecting and laying tubing lines
– Select the tubing line length such that adequate leeway is available
in order to accommodate changes in length which result from pressure.
– Avoid mechanical stressing of the tubing line.
– Do not bend the tubing line into a radius of less than its specified minimum bending radius
of 51 mm.
– Do not twist the tubing line during installation.
– Make sure that tubing lines do not become kinked.
• Mark the completed tubing connections in the hydraulic circuit diagram.
Exercise 1-1 – Examining performance for a controller using constant displacement pump and fixed pressure limitation
© Festo Didactic 574166 Name: __________________________________ Date: ____________ 7
2. Becoming familiar with the commissioning procedure
Information
During practice operation and for industrial maintenance purposes, safe commissioning is
undertaken at low pressure which is then increased up to the maximum value. This is possible with
either a pressure-relief valve or a pump recirculation circuit. At low pressure, leaks can be safely
detected after device replacement, for example.
Commissioning procedure with pump recirculation circuit
1. Switch to pump recirculation by opening the shut-off valve.
2. With electro-hydraulic controls, activate the electrical 24 V DC control voltage.
3. Switch the hydraulic pump on.
4. Slowly close the shut-off valve until a circulating pressure of approximately 15 bar prevails.
Immediately set the pump back to recirculation in the event of leaks.
5. Run the sequence once and watch for leaks.
6. Fully close the shut-off valve and set the pressure limit at the pressure-relief valve of the
hydraulic power unit to the specified value.
3. Finding out about the procedure when taking measurements in the electrical circuit
Safety instructions
• Before measuring, make sure that the section of the controller in which you intend to take
measurements only works with an electrical voltage of no greater than 24 V DC!
• Measurements within sections of the controller which function with higher voltages (e.g. 230 V)
may only be performed by persons who have received appropriate training or instruction.
• Incorrect performance of this measurement is life endangering!
• Observe the safety precautions for working with electrical power!
Exercise 1-1 – Examining performance for a controller using constant displacement pump and fixed pressure limitation
8 Name: __________________________________ Date: ____________ © Festo Didactic 574166
Information
Procedure for performing measurements in the electrical circuit
1. Switch off supply power to the electrical circuit.
2. Select the desired operating mode at the multimeter (e.g. direct current measurement).
3. Connect the measuring instrument with correct polarity when measuring direct current/
direct voltage.
4. Select the largest measuring range.
5. Switch supply power to the electrical circuit back on.
6. Watch the display and switch to increasingly smaller measuring ranges step-by-step.
7. Read the value from the display after arriving at the smallest possible measuring range.
4. Double checking the controller setup
Observe the following points when commissioning the controller:
• Before commissioning, make sure that all tank lines have been connected and that all couplings have
been securely fitted.
• Fully close the flow control valve 1V3.
• Fully open both pressure-relief valves 1V1 and 1V4.
• Switch to pump recirculation by opening shut-off valve 1V2.
• Switch off the 24 V DC electrical supply voltage for the flow sensors and pressure switches.
Note
You will find information on the sensors in the operating instructions.
When using the analogue output of the pressure switch, make sure it is set to between 0-10 V.
• Switch the hydraulic power unit on.
• Slowly close the shut-off valve 1V2. The entire pump unit delivery rate flows at low pressure through the
pressure-relief valve 1V1 to the tank.
Immediately set the pump back to recirculation in the event of leaks.
• Set the pressure at the pressure-relief valve 1V1 to 45 bar.
• Perform the measurement tasks.
5. Measuring pressure and flow rate at different load pressures
Execution
Set the pressure-relief valve 1V1 to 45 bar. Set the values indicated in the table for the flow control
valve 1V3 and the pressure-relief valve 1V4. Measure the pressure and flow rate for these values.
Exercise 1-1 – Examining performance for a controller using constant displacement pump and fixed pressure limitation
© Festo Didactic 574166 Name: __________________________________ Date: ____________ 9
– Set the values indicated in the table. Enter the measured pressure and flow rate values into the table.
Load case Valve specifications Pump pressure p1 [bar]
Flow rate q1 [l/min]
Load pressure p2 [bar]
Flow rate q2 [l/min]
a 1V3: open
1V4: Minimum pressure
b 1V3: open 30
c 1V4: Minimum pressure 0.5
d — 30 0.5
e — 25 2
f — 1 0
Measurement log
Notes
Fully open the flow control valve 1V3 before dismantling the controller.
Fully open the pressure-relief valves 1V1 and 1V4 before dismantling.
6. Calculating the pumping power, effective power and power loss
Information
The formula for calculating the power in the hydraulic system when using the indicated physical
units is:
600q pP ⋅
=
P Power [kW]
q Flow rate [l/min]
p Pressure [bar]
Power output of the pump unit: PP
1 1P 600
q pP
⋅=
PP Power output of the pump unit [kW]:
q1 Flow volume of the pump unit [l/min]
p1 Pump pressure [bar]
Exercise 1-1 – Examining performance for a controller using constant displacement pump and fixed pressure limitation
10 Name: __________________________________ Date: ____________ © Festo Didactic 574166
Effective power (output of the consuming device): PL
2 2L 600
q pP
⋅=
PL Output of the consuming device [kW]
q2 Flow rate to the consuming device [l/min]
p2 Load pressure [bar]
Power loss: PV
V P LP P P= −
PV Power loss [kW]
a) Calculate the pumping power, effective power and power loss for the load cases a to f (see workbook 4).
Enter the values to the table.
Load case Pumping power
PP [kW]
Effective power
PL [kW]
Power loss
PV [kW]
a
b
c
d
e
f
Performance for the load cases a to f
Exercise 1-1 – Examining performance for a controller using constant displacement pump and fixed pressure limitation
© Festo Didactic 574166 Name: __________________________________ Date: ____________ 11
b) Transfer the performance values for load cases a to f to a bar chart.
PP Pumping power
PL Effective power
PV Power loss
Performance of the system with constant displacement pump and pressure limitation with different load cases a to f
c) When is power loss PV particularly high? Give reasons for your answer.
Exercise 1-1 – Examining performance for a controller using constant displacement pump and fixed pressure limitation
12 Name: __________________________________ Date: ____________ © Festo Didactic 574166
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