Experiment No.10

8/20/2019 Experiment No.10

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Lab Experiment 10

Linear Velocity

To demonstrate the working principle of Geneva mechanism on a

laboratory scale apparatus

!erformance "b#ectives$

i To understand the work principle of Geneva mechanismii To learn the importance in textile Engineeringiii To indentify the factors a%ecting the performance of Geneva mechanism

&pparatus$

Laboratory scale designed of Geneva mechanism

'iscussion ( Theory $

The Geneva mechanism was originally invented by a watch maker. The

name derives from the devices eerier application in mechanical watches

Switzerland and Geneva being an important concern of watch making. It is

also known as pin and star wheel. It is a devise which is used to convert the

continues rotary into an intermittent rotary motion.

As show in the Figure !" the driver wheel is an ordinary sprocket with

a pin #tted as a point near the circumference. The driven wheel is shaped as

show and has radical slots cut at regular intervals around its circumference.

As the pin rotates" it enters one of these slots" moves the driven through a

pre$determined angle" and then leaves the slot so that the movement of the

driven wheel casts. The drive wheel also has a raised circular blacking dies

that locks the driven wheel position between stops. The mechanism needs to

be well lubricated% it is often enclosing in a capsule.

The number of slots around the dream wheel" the number and positionof pin on the &enver wheel and the shaft spacing are arranged in achieve

the desired intermittent movement of the denser wheel. There is usually a

large huu on the driver wheel to keep the star wheel locked in position when

it is not turning.

Geneva )heel 'esign$

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)ame* +uhammad ,mar -oll )o. /0$!1

Score* 222222222222 Signature of the lab tutor*2222222222222222222 &ate*

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Lab Experiment 10

Linear Velocity +any factors contribute to a successful Geneva mechanism design

such as material used" surface #nish" tolerances" loads" stress levels"

lubricant" etc. ,nsuccessful e4perimental application of this mechanism usually

results in two modes of failure pin wear and wheel breakage of thesetwo modes" wear is the handset to control.

The present design approach here is to reduce wear by altering the

geometry of wheel to reduce the contact stress while maintaining

acceptable stress level in other regions of the wheel. The design of the Geneva mechanism is initiated by specifying the hub

radius" the roller diameter and the number of slots. At least / slots are

necessary but most problems can be solved with wheel having from 1

to ! slots.

The lower wheel drives the upper one. The national movement of the

lower wheel is continues but the upper wheel only rotates

intermittently 5in steps6. It takes si4 revolutions of the lower wheel to

produce one revolution of the upper wheel. If there is si4 slots present

in the star wheel.

The drive pin on the lower wheel engages with the slots onthe Geneva

7heel and makes it turn 8ust enough so that it is position when the pin

comes round again.

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Lab Experiment 10

Linear Velocity

!rocedure ( *ethod$

. &emonstrate the parts and working principle of the entire apparatus while it

is turned o9.

!. 'lug in the main power supply and e4plain the mechanics involved in thedesign of the apparatus" while the apparatus is running.

/. :4plain the variable factors e4ist in the apparatus" such as number of slots in

the drive wheel and number of pins on the driving wheel.1. -emove the main power supply.

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Lab Experiment 10

Linear Velocity

Test +esults ( +eport$

The test result s 3 report should include the following particulars*

6 +anufacturer and model.!6 Important parts./6 )o of pins in drive wheel.16 )o of slots in driven wheel(6 Type of belt used.

+eview ,uestion$

. 7hy the Geneva +echanism is called as 'in and star wheel;

!. State the applications of Geneva mechanism in te4tile;

/. &iscuss the factors by which we can regular the movement of the driven wheel;

-inal .hecklist$

. <lean your apparatus and workbench before you leave.

!. =eep the apparatus back to their proper places.

/. Submit your answer to >uestions together with your data" calculations and results ?eaving

the laboratory.

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Lab Experiment 10

Linear Velocity

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Experiment No.10