1. Clutches

2. Clutch Construction and Operation
This presentation will explore:
Clutch Components and Construction
Basic Clutch Operation
Clutch Operating Mechanisms

3. Reason For Clutches Used with manual transmission systems.
Provide link between engine and transmission system.
Allow smooth take up of drive.
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4. Reason For Clutches
Clutch allows for brief separation between engine and gearbox.
Provides temporary disconnection when vehicle stopped in gear.
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5. Clutch Action Clutch action can be demonstrated by two discs .
Drive disc
Engine
Clutch action can be demonstrated by two discs .
Driven disc
Input shaft to transmission
Drive disc attached to engine.
Driven disc attached to transmission input shaft.
Driven disc disconnected, no drive.
Driven disc in contact with drive disc, drive applied.
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6. Pressure plate assembly
Clutch System Parts
Clutch system consists of:
Clutch plate
Flywheel.
Release bearing
Clutch Plate (driven plate).
Clutch
housing
Pressure Plate Assembly.
Release Bearing.
Flywheel
Clutch Fork.
Pressure plate assembly
Clutch fork
Clutch housing protects clutch components from outside elements.
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7. Clutch System Parts - Clutch Plate - 1
Located between flywheel and pressure plate.
Rivets
Friction material
Splined hub
Splines mesh with input shaft.
Frictional material riveted to cushion springs on either side of friction ring.
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8. Clutch System Parts - Clutch Plate - 2
Cushion springs
Cushioning springs cushion force as pressure plate pushes clutch plate onto flywheel.
Torsional spring
Torsional springs soften load applied to clutch plate as it begins to turn.
Cushion springs
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9. Clutch System Parts - Pressure Assembly - 1
Used to push clutch plate onto flywheel.
Two types of pressure plate: Coil Spring and Diaphragm Spring.
Pressure plate
Assembly comprises:
Cover
Diaphragm/coil spring.
Pressure plate.
Cover.
Diaphragm spring
Coil spring type uses a number of coil springs to push pressure plate against clutch plate.
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10. Clutch System Parts - Pressure Assembly - 2
Cover
Diaphragm spring pressure plate assembly uses dish-shaped spring.
Diaphragm spring
As spring is pushed toward engine, clutch plate released.
Pressure plate
Pivot rings
As spring is released, pressure returned to clutch plate.
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11. Clutch System Parts - Release Bearing & Clutch Fork
Release bearing and clutch fork move pressure plate.
As clutch fork moves, it pushes release bearing and disengages pressure plate from clutch plate.
As clutch fork moves in the other direction, release bearing engages clutch plate.
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12. Basic Clutch Operation - 1
A foot pedal operates clutch fork via a link.
Releasing foot pedal engages clutch.
Pedal action should be smooth to prevent judder.
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13. Basic Clutch Operation - 2
Clutch pedal must be be easy to operate, so levers (or hydraulics) are used to increase effort.
Force at cable: 100N x 3 = 300N 1 4 3
Pressure of 100 Newtons (22.5 lb) applied to foot pedal.
Multiplied by the pivot ratio of (3:1) on the pedal to a force of 300 Newtons (67.5 lb) on the cable.
Force at release bearing: 300N x 4 = 1200N
100N at pedal
Multiplied by the pivot ratio on the clutch fork of (4:1) to a force of 1200 Newtons (270 lb) at the release bearing.
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14. Clutch Operating Mechanisms - Mechanical
Multi-stranded steel wire cable connected between clutch fork and foot pedal.
Outer sheath
Wire cable
Wire protected by flexible outer sheath.
As pedal depressed, it pivots operating clutch fork.
Return spring
Return spring helps return clutch fork to rest position.
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15. Clutch Operating Mechanisms - Hydraulic
Master cylinder
Slave cylinder
Pipe connected between foot pedal and clutch fork.
Two cylinders: master cylinder and slave cylinder.
Pipe
As foot pedal depressed, master cylinder builds pressure in system, slave cylinder activated.
As foot pedal released, springs return system to rest position.
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16. Summary You should now be aware of: Clutch Components and Construction
Basic Clutch Operation
Clutch Operating Mechanisms
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