Mechanism of Clutch type (Pressure ring-based) limited-slip differential?

Pressure ring-based:

One of the wheels encountered a slippery surface

    A differential is one, which enables normal and smoothing operation of the drive wheels. In the previous post, we have seen about the construction and operation of the open differential method, which is used to control the speed of the drive wheels independently. Through this process, both wheels are made to cover a specific distance at an exact time, when a turn is made. But it has a disadvantage, by which if one of the wheels has encountered a slippery surface, most of the engine power is transferred to the slippery wheel and the vehicle is unable to move. This disadvantage is overcome by the Limited Slip Differential (LSD). There are various types of LSD used namely,

1.          Clutch type (Pressure ring based)

2.          Clutch type (Preload spring-based)

3.              Hydraulic Locking type

4.          Torsen Differential

 

    Among the above types, Clutch type (Pressure ring Based) LSD is most preferred. Now let’s see about the construction and operation of the Pressure ring-based Clutch type LSD.

Complete setup of Clutch type (Pressure ring spring-based) limited-slip differential

Pressure ring

     Pressure ring-based LSD is completely a different process compared to the normal slip differential. As shown in the above figure, at first the engine power is transferred from the pinion gear to the ring gear, from which the power is transferred to the case which is placed in the slots of the ring gear.  Inside the slots of the case, a pair of pressure rings containing a single or double pair of spider gears is placed. In this LSD, the spider gears are placed inside the grooved slots of the pressure rings rather than attaching directly to the ring gear like the open differential method. Then two drive wheels attached to the side gears are also well meshed to the spider gears. So the power flows from the case to the pressure rings and then to the spider gears and side gears. Then a set of clutch packs is placed across both sides of the pressure rings. These clutch packs consist of both steel plates and frictional plates. The steel plates are fitted with the case and the frictional plates are fitted with the side gears. When the clutch pack is well pressed, the steel plates which is attached to the rotating case makes contact with the frictional plates and makes both the side gears to rotate at the same speed. Therefore both the wheel rotates at the same speed even though in a slippery condition.

Clutch packs placed at both the sides of the pressure rings

Clutch packs with the pressure ring are placed inside the case

    Consider an instance where one wheel has encountered in a slippery condition. Now when the vehicle is in this condition it is natural that the driver will press the accelerator. So the slippery wheel will rotate at a faster rate than the other wheel. As one wheel travels at a higher speed than the other, one side gear will rotate faster than the other side gear. If that particular side gear begins to rotate suddenly, a sudden acceleration will be made. This sudden acceleration causes the spider gear to push in the opposite direction causing the pressure rings to open. Once the pressure rings got separated it will press the clutch pack present at both the side of the pressure rings, which will make the steel plates attached to the case, to make in contact with the frictional plates attached with the side gears. So both the side gears move at the same speed as the case and the wheels are able to overcome the slippery action.

 

Movement of the spider gear inside the pressure ring, when the sudden jerk is caused

   So the main purpose of the limited-slip differential is, during a slippery action instead of giving most of the engine power to one wheel, the power is transferred to both the wheels to overcome the problem.