Standard Differential

Torque is split and balanced right to left regardless of speed or speed differences right to left. This is done by all the torque going through pinion gears and a free spinning differential case where the case will spin at any imbalance in torque from right to left.

Limited Slip Differential

Torque is split right to left but can be out of balance to a designed limit. The torque all goes through pinion gears that deliver torque to each side as in the standard diff., however the differential case is not free to spin. This resistance to spinning allows a torque imbalance right to left. The amount of the imbalance is governed by the amount of resistance to spinning of the case. When imbalance reaches the design level, the case will spin. There are several different ways to create this resistance. In the PRA-352 axle this is done by a series of clutch plates. The separating forces in the side gears actuate these plates to create a frictional resistance to the case spinning. Since the separating force is greater as the gears are taking more torque, the resistance to spinning goes up in proportion to the torque. The amount of imbalance right to left then is a multiplier of the torque. This referred to as bias ratio.

No-Spin

The no spin does not split torque but acts as a solid lock right to left up to a point where if one wheel wants to roll faster than it is being driven, it can roll ahead. This is accomplished using dog teeth that lock side to side, but when one side want to go faster, cams disengage the dog teeth on that side.

Standard Differential

The torque to each tire remains the same at all times. If the tire on one side gets in poor traction condition compared to the opposite side and there is sufficient torque applied, that wheel will slip. The torque available to the non-slipping side is equal to the torque on the slipping side. The slipping tire has increased tire speed resulting in spinning of the differential case. This is called a "spin-out". The total torque is dependent on the ground coefficient on the worst side and is equal to twice that value. If the total torque is not enough to keep the vehicle moving, the vehicle and the wheel on the good traction side can stop resulting in the slipping tire to have a speed twice the normal speed. Maximum traction is only achieved when traction condition on each side is equal.

Limited Slip Differential

The torque to each tire can be different up to the limit or bias that is designed into the diff. If the tire on one side gets into poor traction condition compared to the other side when the ground coefficient difference is more than the diff. design bias, and there is sufficient torque applied, that wheel will slip. The torque to the opposite side will be equal to the torque on the slipping side times the bias ratio. It is therefore still possible to have a "spin-out" condition when a large difference in ground conditions side to side exists. The total torque when this happens is dependent on the ground coefficient on the poor traction side with the total torque equal to the bias ratio plus one times the torque at the slipping tire. If the total torque is not sufficient to propel the vehicle the vehicle and one wheel will stop as with the standard diff. Maximum traction is achieved when the traction condition on each side does not vary by more than the diff. bias ratio.

No-Spin

The torque to each side can vary with out limit. The wheels are locked together and both will spin if sufficient torque is applied. Maximum traction is always achieved regardless of side to side traction differences.