The limited slip differential is a direct replacement for the standard differential. The limited slip differential is available in both the front axle group and the rear axle group.
Illustration 1 | g00280829 |
Limited Slip Differential (1) Case housing (2) Thrust washer (3) Clutch pack (4) Actuator housing (5) Side gears (6) Pinion (gears) (7) Pinion (gears) (8) Pinion shafts |
Illustration 2 | g00352596 |
Locking Ratio (4) Actuator housing (8) Pinion shaft (9) 50 degree angle |
When the wheels have equal traction, the limited slip differential sends an equal amount of power to both of the wheels. Power to both wheels with the limited slip is similar to the function of the standard differential. One wheel begins to turn faster than the other wheel if there is a loss of traction. When one wheel is faster than the other, the internal forces that are present between shaft (8) and actuator housings (4) will react on 50 degree angle (9). The internal forces push actuator housings (4) against clutch packs (3). The torque of the clutch pack limits the loss of traction to the wheel that is turning faster.
The limited loss of traction is due to the internal friction of the differential. This effect is produced by two clutch packs (3) which are arranged symmetrically in the differential housing. In a standard differential, one wheel can be held in position when the engine is running and a gear is engaged. The other wheel will turn faster. In the limited slip differential, the above procedure would be more difficult because of clutch packs (3). The above procedure will become more difficult as power increases.
The limited slip differential is identical on the left side and the right side of two pinion shafts (8). The limited slip differential contains the following components: two thrust washers (2), two clutch packs (3), two actuator housings (4), two bevel gears (5) and four pinion gears (7) .
The inside splines of side gears (5) are connected to the sun gears for the final drives. The outside splines of side gears (5) are meshed with the inner friction discs in clutch packs (3). The side gears send the power through the sun gears and to the final drives.
Housing (1) is fastened to the bevel gear. Housing (1) has inner grooves which hold the outer discs. The outer discs are in clutch pack (3). The clutch pack also has inner discs between the outer discs. The inner discs are splined to the side gears. Actuator housings (4) also fit in the same grooves. The actuator housings are held with the discs from moving radially. Side gears (5) fit into actuator housings (4). Pinion shafts (8) also fit into actuator housings (4). The pinion shafts lie in the 50 degree notches in the actuator housings. Pinion gear (6) and pinion gear (7) are installed on the pinion shafts.
Illustration 3 | g00280979 |
Disassembled Limited Slip Differential (1) Housing (2) Thrust washer (3) Clutch pack (4) Actuator housing (5) Side gears (6) Pinion (gears) (7) Pinion (gears) (8) Pinion shafts |
Operation of the Limited Slip Differential
Illustration 4 | g00352597 |
Normal No-slip Conditions |
The limited slip differential operates identically to a standard differential during straight forward operation or during straight reverse operation. The limited slip differential provides 50 percent torque to each wheel.
Illustration 5 | g03012342 |
Maximum Slipping Conditions |
When one wheel begins to turn faster than the other wheel, the clutch pack on the faster turning wheel is slipping. The slipping indicates that only 30 percent of the input torque is available at that wheel. 70 percent of the input torque is available to the slower turning wheel. For example, the inside tire during a turn provides 70 percent of the traction.
The advantage of a limited slip differential over a standard differential is shown by the difference in torque.
A standard differential could only transfer the same amount of torque from the slipping side to the opposite side. The limited slip differential can transfer 2.3 times the amount of torque to the slipping side. The overall advantage of the limited slip differential would be a 40 percent increase in traction to the slipping side.