VMD - Lecture 9 -Clutches

8/4/2019 VMD - Lecture 9 -Clutches

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Vibration & Machine Design(MCT-320)

Lecture 9Machine Design - Clutches

Dr. Kashif Saeedemail: [email protected]

University of Engineering and Technology, Lahore.

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MCT 320 Vibration & Machine Design

Objectives Understand the Basics of Engineering Vibration (Before Mid) Designing Bearings, Gears, Breaks and Clutches (After Mid)

Text Book Engineering Vibration by Daniel J. Inman Mechanical Engineering Design by Joseph E. Shigley

Reference Books Mechanical Vibration by Singiresu S. Rao Vibration with Control by Daniel J. Inman. Machine Design An Integrated Approach by Robert L. Nortion

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Clutches

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What does Clutch means in English ?

Verb : Grasp or SeizeNoun : A tight grasp

What is a mechanical Clutch ?

A clutch is a mechanical member used toconnect a driving shaft to a driven shaft

so that the driven shaft may be started orstopped at will.


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Clutches

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What can be possible applications of clutches ?Clutches are used whenever the ability to limitthe transmission of power or motion needs to

be controlled either in amount or over time.

AutomobilesElectric screwdrivers

What kind of mechanism can be used to

design a clutches ?Two types :

1. Positive clutches2. Friction clutches


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Clutches Positive Clutch

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A clutch that consists of two surfaces withinterconnecting elements, such as teeth, thatlock together to prevent slipping.

Positive clutches are also known asmechanical lockup clutches.

Used for positive drive

What kind of Interconnecting elementscan be designed ?


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Clutches Positive Clutch

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Clutches Friction Clutch

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A mechanical clutch that transmits torquethrough surface friction between the faces ofthe clutch

What would be some principle designconsiderations ?

Used principally in the transmission of powerof shafts and machines which must be started

and stopped frequently.

Frictional force should pickup and hold the load

Heat of friction should be readily dissipated

Reasonably uniform distribution of pressure


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M ATERIAL

What kind of material should be used ?

High and Uniform coefficient of friction

Not affected by moisture or oil

Withstand high temperature

High heat conductivity

High resistance to wear

What is the most common materialhaving all these properties ?

Cast Iron


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M ATERIAL

Modern clutches typically use a compound organic resin with copper wirefacing or a ceramic material. A typical coefficient of friction used on a

friction disc surface is 0.35 for organic and 0.25 for ceramic


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T YPES

Many types, Most Common being :

Disc or Plate Clutch


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T YPES



Cone Clutch

The cone clutch transfers a higher torque than plate or disk clutches of thesame size due to the wedging action and increased surface area.


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T YPES

Centrifugal Clutch



Cone Clutch

A centrifugal clutch is a clutch that usescentrifugal force to connect two concentric

shafts, with the driving shaft nested inside thedriven shaft

As the load increases, the speed drops,disengaging the clutch, letting the speed rise

again and reengaging the clutch.


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D ESIGN P LATE OR D ISC C LUTCH

Every machine should fulfill certain requirements

How to Design a Plate or Disc Clutch ?

What are the requirements that a Plate orDisc Clutch should fulfill?

Transmit a certain amount of powerOr

Deliver a certain amount of torque at a given speed

What are the unknowns that are to becalculated ?

Pressure

Dimensions


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D ESIGN P LATE OR D ISC C LUTCH

Documents

VMD - Lecture 9 -Clutches