Transcript Automotive Drivetrains

Automotive Drivetrains
CLUTCHES
Purpose
To connect and disconnect engine power flow to
the transmission at the will of the driver.
Clutch System
•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
•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 ...
•The engine power
will transfer
through the
clutch to the
road
System
Components
•Flywheel: Transfers engine power to the
clutch
•Input shaft: Transfers power from
clutch to the transmission
•Clutch Disk (clutch): Splined to input
shaft; transfers power from engine to
the input shaft
•Pressure Plate Assembly: Spring pressure
tightly holds the clutch to the flywheel
Components cont:
•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
•Pilot Bearing (bushing) : Mounted in the
tail of the crankshaft. Stabilizes the
input shaft. Not always used for FWD.
•Clutch Fork (if applicable): Slides the
release bearing into and away from the
pressure plate assembly
Components cont:
•Clutch Linkage (or hydraulic plumbing):
Allows the driver to operate the clutch
fork
•Clutch (bell-housing) Housing: Encloses
the clutch assembly
–May be integral with the transmission or removable
Clutch Components Flywheel
•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
Flywheel Construction
•Usually constructed
of nodular cast iron
which has a high
graphite content
•The graphite helps
lubricate
engagement of the
clutch
•May also be
constructed from
cold rolled steel
Dual-mass Flywheel

The flywheel hub
and clutch mating
area are two
separate
components
 Springs are used to
dampen engine and
clutch engagement
oscillations
Dual-mass Flywheel
Flywheel Measurements
Run-out – measured with a dial indicator
Parallelism – straight-edge & feeler gauge
Thickness – micrometer or dial indicator
Clutch Components
Input (clutch)
shaft
•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
Clutch Components – Clutch
Disc
•Is squeezed between the flywheel and the pressure
plate
•Transmits power from the engine crankshaft to the
transmission input shaft
Clutch Disc Construction
Facing manufactured with frictional material
(may contain asbestos)
Other surface materials include:
•paper-based
•ceramic
•cotton
•brass
Clutch Disc Types
• Rigid - used
primarily for
industrial/racing
applications.
•Flexible - most
common, everything
from grandma’s
cruiser to
street/strip racing.
Flexible Clutch Disc
•Hub flange - in direct contact with the input shaft
•Friction ring - in direct contact with the
flywheel/pressure plate.
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)
Clutch Components
Pressure Plate (clutch cover)
•Squeezes clutch disc onto flywheel
•Can be engaged or disengaged
•Acts like a spring-loaded clamp
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
Belleville/diaphragm Spring:
Spring-type Pressure Plate
Benefits and Disadvantages:
Belleville/diaphragm type:
•cost effective
•uniform engagement
•limited spring pressure
Spring:
•unlimited pressure capabilities
•as springs wear, pressure may become
inconsistent
Clutch Components
Release (throw-out) bearing
•Operated by the clutch linkage
•Presses against the pressure plate to release
the clutch
Clutch Components
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
Clutch linkage – Mechanical
Linkage-type
Clutch linkage – Mechanical
Cable-type
Clutch linkage – Hydraulic
Most Commonly used today
Hydraulic Clutch Master
Hydraulic Clutch Slave
Hydraulic Clutch Slave
Concentric-type
Dual-clutch Transmission



Essentially an
“automatic” manual
transmission
Delivered to the
mainstream by
Volkswagen – now
being used/developed
by most mfg.
Eliminates the “power
sucking” torqueconverter of an
automatic transmission
Dual-clutch Transmission



Utilizes two input
shafts – one inside
of the other
Each input shaft will
have a dedicated
clutch or clutch pack
splined to it.
A processor
(computer) will
engage one or the
other clutches (or
neither for neutral.)
Dual-clutch Transmission

May use a wet or dry “clutch-pack”
Dual-clutch Transmission

or conventional clutch disc design
Dual-clutch Transmission

Each of the
input-shafts
controls half
of the
transmissions
gear-sets
Dual-clutch Transmission