LIMITED SLIP DIFFERENTIAL Introduction What is a Differential? A differential is a device that splits the engine torque in two ways, allowing each output to spin at a different speed. Facilitates the driven wheels to rotate at the same speed while on a straight road. Allows the outer wheel to rotate faster than the inner wheel, while taking a curve or traveling on an uneven surface. Main Functions To aim the engine power at the wheels. To act as the final gear reduction in the vehicle, slowing the rotational speed of the transmission one final time before it hits the wheels. To transmit the power to the wheels while allowing them to rotate at different speeds. Need For Differential Driven wheels demand different RPM’s at different situations. A great deal of force is required to make a tire slip, while cornering a curve. Heavy strain on the axle components. Open Differential Disadvantage Always applies the same amount of torque to each wheel. Slipping of wheels having less traction. Not suitable for off-road driving Limited Slip Differential (LSD) It rules out the disadvantages of an open differential. Uses various mechanisms to allow normal differential action when going around turns. When a wheel slips, they allow more torque to be transferred to the non- slipping wheel. Reduces Slipping of wheels to a great extent. Classification Three main types of LSD’s: 1) Clutch type 2) Viscous Coupling 3) Worm & Wheel LSD Clutch Type LSD Main Components same as that of an open differential. It adds a Spring Pack and a set of Clutches. Spring pack along with the clutches provides a Preload. Constructional Details Working Both side gears spin with the cage during normal operation. If one wheel wants to spin faster than the other, it must first overpower the clutch. Viscous Coupling No gear train involved. Power is transferred through highly viscous fluid. Used in All Wheel Drive (AWD) vehicles. Worm & Wheel LSD Most efficient among all the LSDs. Worm and worm gears replaces the pinions and side gears in an open differential. It works on the principle that “a worm gear can turn a worm wheel, but the worm wheel is not capable of turning the worm gear”. Working Working As the carrier is turned by the ring gear, it forces the worm wheels to rotate with it. Because the wheel is unable to turn the worm gear, this transfers power to axle shaft. Working In a corner when differential action is required the inside axle slows, slowing the worm gear to which it is attached. This in turn twists the worm wheels in which it is contact. Working As these worm wheels twist they turn the spur gear. This spur gear turns the spur gear of the second worm wheel, which is in contact with the worm gear of the outer wheel shaft. Questions……???
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