A slipper clutch ''(also known as a back-torque limiter)'' is a specialized

clutch A clutch is a mechanical device that engages and disengages power transmission, especially from a drive shaft to a driven shaft. In the simplest application, clutches connect and disconnect two rotating shafts (drive shafts or line shafts). ...

with an integrated freewheel mechanism, developed for performance-oriented

motorcycle A motorcycle (motorbike, bike, or trike (if three-wheeled)) is a two or three-wheeled motor vehicle Steering, steered by a Motorcycle handlebar, handlebar. Motorcycle design varies greatly to suit a range of different purposes: Long-distance ...

s to mitigate the effects of engine braking when riders decelerate. The main purpose of a slipper clutch is to prevent over engine rev and rear wheel hop (or clatter) especially under hard braking in a vehicle (usually performance motorcycles). It does so by partially slipping until engine's speed matches with the vehicle's speed upon sudden braking.

Design

The slipper clutch consists of two bases, one with dog clutches and ramps with

ball bearing A ball bearing is a type of rolling-element bearing that uses balls to maintain the separation between the bearing races. The purpose of a ball bearing is to reduce rotational friction and support radial and axial loads. It achieves this ...

s, a splined hub, and clutch plates. In normal operation, the dog clutches mate, driving the transmission. When a back torque comes from the transmission, the splined hub slides up the bearing ramps, disconnecting from the clutch plates and allowing a limited slip between input and output. This type of clutch is designed to partially disengage or "slip" when the rear wheel tries to drive the engine faster than it would run under its own power. The engine braking forces in conventional clutches will normally be transmitted back along the

drive chain Chain drive is a way of transmitting mechanical power from one place to another. It is often used to convey power to the wheels of a vehicle, particularly bicycles and motorcycles. It is also used in a wide variety of machines besides vehicles. ...

causing the rear wheel to hop, chatter or lose traction. This is especially noted on larger displacement

four-stroke engine A four-stroke (also four-cycle) engine is an internal combustion (IC) engine in which the piston completes four separate strokes while turning the crankshaft. A stroke refers to the full travel of the piston along the cylinder, in either directi ...

s, which have greater engine braking than their

two-stroke A two-stroke (or two-stroke cycle) engine is a type of internal combustion engine that completes a power cycle with two strokes (up and down movements) of the piston during one power cycle, this power cycle being completed in one revolution of ...

or smaller displacement counterparts. Slipper clutches eliminate this extra loading on the rear suspension giving riders a more predictable ride and minimize the risk of over-revving the engine during downshifts. Slipper clutches can also prevent a catastrophic rear wheel lockup in case of engine seizure. Generally, the amount of force needed to disengage the clutch is adjustable to suit the application. Slipper clutches have also been used to a lesser extent on automobiles, primarily those powered by motorcycle engines. They can also be found on racing remote control cars. Some

experimental aircraft An experimental aircraft is an aircraft intended for testing new aerospace technologies and design concepts. The term ''research aircraft'' or '' testbed aircraft'', by contrast, generally denotes aircraft modified to perform scientific studies, ...

use a slipper clutch to control torsional resonance in the drive train and protect the engine from shock in the event of a propeller strike. A slipper clutch for an automobile was patented with a French priority date of 1953 to J.Maurice et al. The principle of this slipper is identical to that used in modern motorcycles. One-way sprag clutches have also been used for the same purpose, but are generally not adjustable for disengagement force. Early Honda Shadow models used a design wherein a sprag clutch is connected to just half of the clutch friction plates, allowing the clutch to slip during heavy backloading sufficiently to prevent rear-wheel lockup, while still allowing moderate engine compression braking with the remaining friction plates.

History

Slipper clutches have been used in most high displacement

four stroke A four-stroke (also four-cycle) engine is an internal combustion (IC) engine in which the piston completes four separate strokes while turning the crankshaft. A stroke refers to the full travel of the piston along the cylinder, in either directi ...

road racing Road racing is a form of motorsport racing held on a paved road surface. The races can be held either on a closed circuit or on a street circuit utilizing temporarily closed public roads. Originally, road races were held almost entirely on publ ...

motorcycles since the early 1980s, having been introduced on the Honda NR500 in 1982 in 500GP. Slipper clutches are now fitted to many current

sport bike A sport bike (sports motorcycle, or sports bike) is a motorcycle designed and optimized for speed, acceleration, braking, and cornering on asphalt concrete race tracks and roads. They are mainly designed for performance at the expense of comfor ...

References

External links

Detailed history
* Motorcycle transmissions Clutches {{Motorcycle-stub

Design

History

See also

References

External links