- Clutches connect and disconnect the engine to the transmission, allowing the driver to control power flow. The main components are the flywheel, clutch disc, pressure plate, and release bearing. - When the clutch pedal is depressed, the release bearing pushes the pressure plate away from the flywheel, disengaging the clutch and transmission from the engine. When the pedal is released, the pressure plate squeezes the clutch disc between it and the flywheel to engage power transfer. - Proper clutch operation requires that it can transmit torque, engage gradually, dissipate heat, dampen vibration and noise, and be balanced and compact and easy for the driver to operate.

1. Automotive Drivetrains
CLUTCHES

2. Purpose
To connect and disconnect engine power flow to the
transmission at the will of the driver.

3. Clutch
Requirements of a Clutch
• Transmit maximum torque of the engine.
• Engage gradually to avoid sudden jerks.
• Dissipate maximum amount of heat.
• Damp the vibrations and noise.
• Dynamically balanced.
• As small as possible.
• Easy to operate.
9

4. •Clutch systems
are used to
disengage the
engine from the
road
•When the clutch
pedal is
depressed, the
clutch (and
transmission) is
disengaged from
the engine
Clutch System

5. •With your foot off of the pedal, the
clutch is engaged to the engine.
•The pressure plate holds the clutch
against the flywheel, allowing power to
travel through the clutch to the input
shaft of the transmission ...
Clutch System
•The engine power
will transfer
through the
clutch to the gear
box.

6. 1. Clutch/Input shaft: Transfers power
from clutch to the transmission
2. Flywheel: Transfers engine power to
the clutch
3. Clutch Disk (clutch): Splined to input
shaft; transfers power from engine
to the input shaft
4. Pressure Plate Assembly: Spring
pressure tightly holds the clutch to
the flywheel
System Components

7. Components cont:
5. Release Bearing (throw-out bearing):
Connected through linkage or hydraulics
to the clutch pedal; Provides a way for
the pressure plate to release pressure
on the clutch
6.Pilot Bearing (bushing) : Mounted in the
tail of the crankshaft. Stabilizes the
input shaft.

8. Components cont:
7. Clutch Fork (if applicable): Slides
the release bearing into and away from
the pressure plate assembly
8. Clutch Linkage (or hydraulic
plumbing): Allows the driver to operate
the clutch fork
9.Clutch (bell-housing) Housing:
Encloses the clutch assembly

10. •Mounted on the rear
of the crankshaft
•Acts as balancer for
engine
•Adds inertia to the
rotating crankshaft
•Provides a surface for
the clutch to contact
•Usually surrounded by
a ring gear for electric
starter operation
Clutch Components –
1.Flywheel

11. 2.Clutch Disc
•Is squeezed between the flywheel and the pressure
plate
•Transmits power from the engine crankshaft to the
transmission input shaft

12. Clutch Disc Construction
Facing manufactured with frictional material
(may contain asbestos)
Other surface materials include:
•paper-based
•ceramic
•cotton
•brass

13. Clutch Disc Types
• Rigid - used
primarily for
industrial/racing
applications.
•Flexible - most
common, everything
from cruiser to
street/strip racing.

14. Flexible Clutch Disc
•Hub flange - in direct contact with the input shaft
•Friction ring - in direct contact with the
flywheel/pressure plate.

15. Flexible Clutch Disc
•Clutch facing -
friction
material
•marcel springs
- facing
dampener
•Torsional springs - further dampening for clutch
application
•Stop pins - limits the torsional spring’s travel
•Rivets -fastens the facing material to marcel (springs)

17. •Squeezes clutch disc onto flywheel
•Can be engaged or disengaged
•Acts like a spring-loaded clamp
3.Pressure Plate (clutch cover)

18. Pressure Plate - Types
Belleville/diaphragm-type Spring: uses a
cone-shaped diaphragm spring for clamping
force.
Multiple-Coil Springs: DUGH!
Semi-centrifugal: clamping force increases
as rotational (centrifugal) force increases

19. Belleville/diaphragm Spring:

20. Spring-type Pressure Plate

21. Benefits and Disadvantages:
Belleville/diaphragm type:
•cost effective
•uniform engagement
•limited spring pressure
Spring:
•unlimited pressure capabilities
•as springs wear, pressure may become
inconsistent

22. •Operated by the clutch linkage
•Presses against the pressure plate to release
the clutch
4. Release (throw-out) bearing

23. 5. Pilot Bearing (bushing)
•Installed (pressed) into a machined bore in the end of
the crankshaft or flywheel
•May be a bushing, ball-bearing or roller-bearing

25. 6. Clutch linkage –
a. Mechanical Linkage-type

26. Clutch linkage – Mechanical
b.Cable-type

27. Clutch linkage –
c.Hydraulic

28. Hydraulic Clutch Master

29. Hydraulic Clutch Slave

30. 7.Clutch (bell-housing) Housing: Encloses the clutch assembly
– May be integral with the transmission or removable

31. •Projects from the front of the transmission
•Usually has a pilot which rides in a
bearing or bushing in the end of the crankshaft
•The clutch disc is splined to the clutch shaft
8. Input (clutch) shaft