Clutches.2011

Automotive DrivetrainsCLUTCHES

Purpose

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

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 ...Clutch SystemThe engine power will transfer through the clutch to the road

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 shaftPressure Plate Assembly: Spring pressure tightly holds the clutch to the flywheelSystem Components

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 assemblyMay be integral with the transmission or removable

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 Clutch Components - Flywheel

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 steelFlywheel Construction

Dual-mass FlywheelThe flywheel hub and clutch mating area are two separate componentsSprings are used to dampen engine and clutch engagement oscillations

Dual-mass Flywheel

Run-out measured with a dial indicatorParallelism straight-edge & feeler gaugeThickness micrometer or dial indicator

Flywheel Measurements

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 shaftClutch ComponentsInput (clutch) shaft

Clutch Components Clutch Disc

Is squeezed between the flywheel and the pressure plateTransmits power from the engine crankshaft to the transmission input shaft

Clutch Disc ConstructionFacing manufactured with frictional material (may contain asbestos)

Other surface materials include:

paper-basedceramiccottonbrass

Clutch Disc Types Rigid - used primarily for industrial/racing applications.

Flexible - most common, everything from grandmas cruiser to street/strip racing.

Flexible Clutch DiscHub flange - in direct contact with the input shaftFriction ring - in direct contact with the flywheel/pressure plate.

Flexible Clutch DiscClutch facing - friction materialmarcel springs - facing dampenerTorsional springs - further dampening for clutch applicationStop pins - limits the torsional springs travelRivets -fastens the facing material to marcel (springs)

Squeezes clutch disc onto flywheelCan be engaged or disengagedActs like a spring-loaded clampClutch ComponentsPressure Plate (clutch cover)

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

Belleville/diaphragm Spring:

Spring-type Pressure Plate

Benefits and Disadvantages:Belleville/diaphragm type:cost effectiveuniform engagementlimited spring pressureSpring:unlimited pressure capabilitiesas springs wear, pressure may become inconsistent

Operated by the clutch linkagePresses against the pressure plate to release the clutchClutch ComponentsRelease (throw-out) bearing

Clutch ComponentsPilot Bearing (bushing)Installed (pressed) into a machined bore in the end of the crankshaft or flywheelMay be a bushing, ball-bearing or roller-bearing

Clutch linkage MechanicalLinkage-type

Clutch linkage MechanicalCable-type

Clutch linkage HydraulicMost Commonly used today

Hydraulic Clutch Master

Hydraulic Clutch Slave

Hydraulic Clutch SlaveConcentric-type

Dual-clutch TransmissionEssentially 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

Dual-clutch TransmissionUtilizes 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.)

Dual-clutch TransmissionMay use a wet or dry clutch-pack

Dual-clutch Transmissionor conventional clutch disc design

Dual-clutch TransmissionEach of the input-shafts controls half of the transmissions gear-sets

Dual-clutch Transmission