Clutch - Grewal

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Clutch
Automotive clutch is used to connect and disconnect the manual
transmission from the engine.
Clutch Parts
Clutch release mechanism – cable, linkage or hydraulic system
allows the driver to disengage the clutch when using foot pedal.
Master Cylinder – any leak in the
hydraulic system will prevent the clutch
pedal from coming back up.
Takes brake fluid.
Slave Cylinder
Cable
Clutch Parts
Clutch Fork – lever that forces the release bearing into the
pressure plate.
Clutch Parts
Release/throw out bearing – bearing that reduces friction
between the clutch fork and the pressure plate.
•Dry or worn bearing will cause a squeal when stepping on the
clutch pedal, worse on a cold day.
Clutch Parts
Pressure plate – spring loaded device that presses the clutch
disc against the flywheel.
Two types – Coil spring and Diaphragm type.
Clutch Parts
Clutch Disc – Friction disc (same material as brakes) splined to
the transmission. There should never be any oil or grease on the
clutch parts.
Clutch facing springs – are use to cushion disc when it engages.
Clutch Parts
Flywheel – provides a mounting place for the clutch and
friction disc assembly.
•Flywheels are made from hardened steel (brake rotors).
•Ring gear around the flywheel can be replaced.
•Grind if cracks (over heating), grooves, or glazed.
•Warped flywheel will cause pulsation in clutch pedal and may
grab at acceleration.
Clutch Parts
Pilot Bearing – bushing or bearing that supports the forward
end of the transmission input shaft.
Clutch
Clutch Problems
Grabbing clutch – vibration or jerking on takeoff.
Cause: Engine mount, friction plate, pressure plate, flywheel.
Dragging Clutch – transmission grind when trying to shift or
engage clutch.
Cause: too much pedal free play, warped or bent friction disc,
oil or grease on the friction disc.
Clutch slippage – RPMs go up, but the vehicle doesn’t move.
Cause: Worn friction disc, miss adjustment of the clutch cable.
Manual Transmission
Manual Transmission
Transmission input shaft – a shaft, operated by the clutch (engine),
that turns the gears inside the transmission.
Transmission Gears – provide a means of changing output torque
and speed.
Synchronizers – devices for meshing gears into engagement and
prevent grinding.
Shift forks – pronged units for moving synchros on there shafts for
gear engagement.
Manual Transmission
Shift linkage – arms or rods that connect the shift lever to the
shift forks.
Gear shift lever – lever allowing the driver to shift gears.
Two types –Internal and external. If out of adjustment might
cause grinding.
Output shaft – shaft that transfers rotating power out of the
transmission to the driveshaft.
Transmission case – housing that encloses transmission shaft,
gears, and lubricating oil.
Counter shaft – Gears on this shaft are attached to the output
shaft.
Manual Transmission
Neutral
Neutral – all the synchronizer sleeves are located in the center.
Input shaft turns and output shaft is stationary.
1st Gear
1st Gear (4.36:1) – Synchronizers engage to the first output gear.
Small gear on countershaft drives a large gear on output shaft
giving high torque and low speed.
2nd Gear
2nd Gear (2.52:1) – 1/2 gear synchronizer is moved away from the
first gear and engaged to the second gear. This provides less torque,
but more speed than the first gear.
3rd Gear
3rd Gear (1.51:1) –3/4 synchronizer is moved to engage the third
gear (1/2 synchronizer is in neutral).
4th Gear
4th gear (1:1) – 3/4 synchronizer is moved to engage the fourth
gear. The synchronizer sleeve locks the input shaft directly to the
output shaft. No torque multiplication.
5th Gear
5th Gear/Overdrive gear (0.87:1) – Keeps the engine speed
down at highway speeds to increase fuel economy.
Reverse Gear
Reverse gear (4.02:1) – Synchronizer is moved onto reverse gear
on the output shaft. Power flows through the counter shaft,
reverse idler gear (changes the direction), reverse gear, and to the
output gear. Reverse light switch is engaged at the same time.
Manual Transmission
Transmission Gear oil
Takes 80W – 90W, also called synchro oil.
If low on oil, might cause noises.
Speedo meter Gear
A gear (worm) is attached to the output shaft to drive the Speedo meter.

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