2 PurposeTo connect and disconnect engine power flow to the transmission at the will of the driver.
3 Clutch SystemClutch systems are used to disengage the engine from the roadWhen the clutch pedal is depressed, the clutch (and transmission) is disengaged from the engine
4 Clutch SystemWith 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
5 System Components Flywheel: Transfers engine power to the clutch Input shaft: Transfers power from clutch to the transmissionClutch Disk (clutch): Splined to input shaft; transfers power from engine to the input shaftPressure Plate Assembly: Spring pressure tightly holds the clutch to the flywheel
6 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 clutchPilot 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
8 Components cont:Clutch Linkage (or hydraulic plumbing): Allows the driver to operate the clutch forkClutch (bell-housing) Housing: Encloses the clutch assemblyMay be integral with the transmission or removable
9 Clutch Components - Flywheel Mounted on the rear of the crankshaftActs as balancer for engineAdds inertia to the rotating crankshaftProvides a surface for the clutch to contactUsually surrounded by a ring gear for electric starter operation
10 Flywheel Construction Usually constructed of nodular cast iron which has a high graphite contentThe graphite helps lubricate engagement of the clutchMay also be constructed from cold rolled steel
11 Dual-mass FlywheelThe flywheel hub and clutch mating area are two separate componentsSprings are used to dampen engine and clutch engagement oscillations
17 Clutch Components Input (clutch) shaft Projects from the front of the transmissionUsually has a pilot which rides in a bearing or bushing in the end of the crankshaftThe clutch disc is splined to the clutch shaft
18 Clutch Components – Clutch Disc Is squeezed between the flywheel and the pressure plateTransmits power from the engine crankshaft to the transmission input shaft
20 Facing manufactured with frictional material (may contain asbestos) Clutch Disc ConstructionFacing manufactured with frictional material(may contain asbestos)Other surface materials include:paper-basedceramiccottonbrass
21 Clutch Disc TypesRigid - used primarily for industrial/racing applications.Flexible - most common, everything from grandma’s cruiser to street/strip racing.
22 Flexible Clutch DiscHub flange - in direct contact with the input shaftFriction ring - in direct contact with the flywheel/pressure plate.
23 Flexible Clutch Disc Clutch facing - friction material marcel springs - facing dampenerTorsional springs - further dampening for clutch applicationStop pins - limits the torsional spring’s travelRivets -fastens the facing material to marcel (springs)
24 Pressure Plate (clutch cover) Clutch ComponentsPressure Plate (clutch cover)Squeezes clutch disc onto flywheelCan be engaged or disengagedActs like a spring-loaded clamp
25 Pressure Plate - TypesBelleville/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
39 Dual-clutch Transmission Essentially an “automatic” manual transmissionDelivered to the mainstream by Volkswagen – now being used/developed by most mfg.Eliminates the “power sucking” torque-converter of an automatic transmission
40 Dual-clutch Transmission Utilizes two input shafts – one inside of the otherEach 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.)
41 Dual-clutch Transmission May use a wet or dry “clutch-pack”
42 Dual-clutch Transmission or conventional clutch disc design
43 Dual-clutch Transmission Each of the input-shafts controls half of the transmissions gear-sets