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For other uses, see Clutch (disambiguation).
Flywheel (100x100)
Flywheel
Flywheel
Clutch for a drive shaft: The clutch disc (center) spins with the flywheel (left). To disengage, the lever is pulled (black arrow), causing a white pressure plate (right) to disengage the green clutch disc from turning the drive shaft, which turns within the thrust-bearing ring of the lever. At rest, all 3 rings connect, with no gaps.
Rear side of a Ford V6 engine, looking at the clutch housing on the flywheel
Rear side of a Ford V6 engine, looking at the clutch housing on the flywheel
Single, dry, clutch friction disc. The splined hub is attached to the disc with springs to damp chatter.
Single, dry, clutch friction disc. The splined hub is attached to the disc with springs to damp chatter.

A clutch is a mechanism for transmitting rotation, which can be engaged and disengaged. Clutches are useful in devices that have two rotating shafts. In these devices, one shaft is typically driven by a motor or pulley, and the other shaft drives another device. In a drill, for instance, one shaft is driven by a motor, and the other drives a drill chuck. A drill (from Dutch Drillen) is The clutch connects the two shafts so that they can either be locked together and spin at the same speed (engaged), or be decoupled and spin at different speeds (disengaged).

Contents

Vehicular

There are many different vehicle clutch designs but most are based on one or more friction discs, pressed tightly together or against a flywheel using springs. Friction is the Force resisting the relative motion of two Surfaces in contact or a surface in contact with a fluid (e A flywheel is a mechanical device with significant Moment of inertia used as a storage device for Rotational energy. A spring is a flexible elastic object used to store mechanical Energy. The friction material varies in composition depending on whether the clutch is dry or wet, and on other considerations. Friction discs once contained asbestos, but this has been largely eliminated. Asbestos is a group of Minerals with long thin fibrous Crystals The word "asbestos" (῾ἀσβεστος is derived from a Greek adjective Clutches found in heavy duty applications such as trucks and competition cars use ceramic clutches that have a greatly increased friction coefficient, however these have a "grabby" action and are unsuitable for road cars. The spring pressure is released when the clutch pedal is depressed thus either pushing or pulling the diaphragm of the pressure plate, depending on type, and the friction plate is released and allowed to rotate freely. Pressure (symbol 'p' is the force per unit Area applied to an object in a direction perpendicular to the surface

When engaging the clutch, the engine speed may need to be increased from idle, using the manual throttle, so that the engine does not stall (although in most cars, especially diesels, there is enough torque at idling speed that the car can move. A throttle is the mechanism by which the flow of a fluid is managed by constriction or obstruction This requires fine control of the clutch). However, raising the engine speed too high while engaging the clutch will cause excessive clutch plate wear. Engaging the clutch abruptly when the engine is turning at high speed causes a harsh, jerky start. This kind of start is desired in drag racing and other competitions, however. Drag racing is a competition in which objects compete to be the first to cross a set finish mark usually from a dead stop and in a straight line

Wet and dry

A 'wet clutch' is immersed in a cooling lubricating fluid, which also keeps the surfaces clean and gives smoother performance and longer life. A lubricant (sometimes referred to as a "Lube" is a substance (often a liquid introduced between two moving surfaces to reduce the Friction between them improving Wet clutches, however, tend to lose some energy to the liquid. A 'dry clutch', as the name implies, is not bathed in fluid. Since the surfaces of a wet clutch can be slippery (as with a motorcycle clutch bathed in engine oil), stacking multiple clutch disks can compensate for slippage.

Operation in automobiles

In a car the clutch is operated by the left-most pedal using hydraulics or a cable connection from the pedal to the clutch mechanism. For the mechanical technology see Hydraulic machinery and Hydraulic cylinder Hydraulics is a topic of science and Engineering A cable is one or more Wires or Optical fibers bound together typically in a common protective jacket or sheath Even though the clutch may physically be located very close to the pedal, such remote means of actuation are necessary to eliminate the effect of slight engine movement, engine mountings being flexible by design. With a rigid mechanical linkage, smooth engagement would be near-impossible, because engine movement inevitably occurs as the drive is "taken up. " No pressure on the pedal means that the clutch plates are engaged (driving), while depressing the pedal disengages the clutch plates, allowing the driver to shift gears or coast. This is the page for mechanical Gears For other uses see Gear (disambiguation For the gear-like device used to drive a roller chain see Sprocket

A manual transmission contains cogs for selecting gears. A manual transmission (also known as a stick shift or just 'stick' 'straight drive' or standard transmission) is a type of transmission used in These cogs have matching teeth, called dog teeth, which means that the rotation speeds of the two parts have a synchronizer, a device that uses frictional contact to bring the two parts to the same speed, and a locking mechanism called a blocker ring to prevent engagement of the teeth (full movement of the shift lever into gear) until the speeds are synchronized.

Non-powertrain in automobiles

There are other clutches found in a car. For example, a belt-driven engine cooling fan may have a clutch that is heat-activated. The driving and driven elements are separated by a silicone-based fluid. When the temperature is low, the fluid is thin and so the clutch slips. When the temperature is high, the fluid thickens, causing the fan to spin. There are also electronically engaged clutches (such as for an air conditioning compressor) that use magnetic force to lock the pulley and compressor together. The term air conditioning refers to the cooling and dehumidification of indoor air for Thermal comfort.

Operation in motorcycles

On most motorcycles, the clutch is operated by the clutch lever, located on the left handlebar. MotorCycle is the title of a 1993 album by Rock band Daniel Amos, released on BAI Records. No pressure on the lever means that the clutch plates are engaged (driving), while pulling the lever back towards the rider will disengage the clutch plates, allowing the rider to shift gears. Motorcycle clutches are usually made up of a stack of alternating plain steel and friction plates. One type of plate has lugs on its inner diameter that key it to the engine crankshaft, while the other type of plate has lugs on its outer diameter that key it to a basket that turns the transmission input shaft. The plates are forced together by a set of coil springs when the clutch is engaged. Racing motorcycles often use slipper clutches to eliminate the effects of engine braking. A slipper clutch (also known as a back-torque limiter) is a specialized Clutch developed for performance oriented Motorcycles to mitigate the Engine braking is the act of using the energy-requiring compression stroke of the Internal combustion engine to dissipate energy and slow down a vehicle

Centrifugal

Some cars and mopeds have a centrifugal clutch, using centrifugal effects to engage the clutch above certain rpm, see Saxomat. Mopeds are a class of low-powered (typically under 50 cc displacement) motorized vehicle generally two or three wheeled A centrifugal clutch is a Clutch that uses Centrifugal force to connect two concentric shafts with the driving shaft nested inside the driven shaft Saxomat was a type of automatic Clutch available as an option on Fiat 1800, Saab 93, Volkswagen Beetle, Borgward, Goliath DKW

Other clutches

See also

External links

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