RA33004630301Z 3.1 - General: General Information on Differential Locks

RA33004630301Z 3.1 - General: General Information On Differential Locks

General Information on differential locks

In the cross-country vehicle series 463 there are three differentials in bevel gear design.

These differentials are required for equalizing the different speeds (particularly in corners) between the front and rear axle and the individual wheels, thus avoiding distortion in the drive train. This additionally provides a considerable improvement in the driving comfort!

With the installation of an interaxle differential in the 3-shaft transfer case (VG 150-3W/2, 16), the anti-lock braking system can also be applied to the drive train (without imitation).

In comparison:

In the series 460 and 461 there is no differential built in the transfer case position "SA" (= on-road 4-wheel), no interaxle equalization can take place between the drive axles. The speed difference of the drive axles has to take place via the wheels/tires which results in distortion when driving on dry roads, and this can then lead to impaired driving comfort and extensive loads being exerted on the drive train.

Note:
In these series an anti-lock braking system (ABS) is not available!

The disadvantage of the differential gears is that on slippery roads or off the road, these differentials perform their job and equalize the different speeds of the axles and the individual wheels - which is what is wanted in this case. In order to avoid this happening, there are three differential locks installed as standard in the model 463.

Under "normal conditions" the power distribution is 50:50, this means: when driving straight ahead, on a dry road, the power to the individual axles is 50% respectively, this results in: front axle 50% and rear axle 50% traction.

With unlocked interaxle differential (in the transfer case) the driving power to the axle with less grip is lost.

If the interaxle differential is locked, this means that each driving axle receives 50% traction respectively (independent of the ground conditions) and the front and rear axle propeller shaft run at the same speed (1 :1).

In order to avoid equalization via the individual wheels, the cross locks in the axles can be selected separately. If all differential locks have been engaged, each individual driving wheel can take up to 25% traction (4x4 = 100% : 4 = 25%). This means that as long as just one wheel has got firm ground under it, traction can still take place via this wheel.

The differential locks are designed as claw-type locks. They are only to be engaged when the locking claw and the mating gear are rotating at the same speed. If this is not observed, considerable damage is caused in the components, which then requires extensive repair work. When the gears have engaged, the differential locks lock to 100%.

This means that very high torques can be transferred to the driving axles free of slip and thus the highest possible traction is achieved.

All Mercedes-Benz cross-country vehicles have a locking effect of 100% when all differential locks are engaged, which means that each of the 4 driving wheels rotates at the same speed, independently of the ground condition.

Task of differential locks

Prevents spinning of a wheel or axle over uneven or slippery ground.

Design
^ electric/electronic (Type 463)
^ pneumatic (Type 463)
^ hydraulic
^ mechanical

Function

By engaging claw couplings the respective differential is locked with the corresponding output shaft. This cancels the function of the differential and effects a 100% locking action.

Arrangement

The differential locks are arranged on the following components:
^ Front axle
^ Rear axle
^ Transfer case (Type 463)

Risk of accident!

Never drive on a firm road surface with engaged differential locks.
With engaged transfer case lock the anti-lock braking system (ABS) is switched off automatically. The ABS indicator lamp in the instrument cluster lights up.
With engaged front axle differential lock the steering properties of the vehicle are impaired.

Apply the parking brake when switching off.

Important! Model 463

When operating on chassis dynamometers (even for short periods) always unflange the front axle propeller shaft and engage the transfer case differential lock, otherwise serious damage is caused to the transfer case.