Understanding Differentials in 4WD Vehicles

Category: Mechanical

Published on 31. Jan 2014 - 16:10 by 1mak

Understanding Differentials in 4WD Vehicles

Employed to allow for the differences in distance traveled between the inner and outer wheels during turns, differentials are present in all vehicles. 4WD vehicles, however, have a differential in each axle. A full-time 4WD vehicle has a center differential contained in the transfer case, as well. The reason for the center differential is because the front wheels of a full-time 4WD will rotate faster than the ones in the back under certain conditions, such as turning corners and forward movement.

What are Open Differentials?

The basic action of an open differential is to prevent problems with scrubbing tires, as well as to reduce understeer in normal cornering and load on the transmission. It allows a single wheel to turn more quickly in the event it needs to do so. In a full-time 4WD vehicle, an unlocked open differential means that if any one wheel loses traction, the others cannot compensate, meaning the vehicle is stuck.

In a vehicle with 4WD engaged, a locked open differential allows one axle to maintain traction if a wheel on the other axle loses contact with the ground.

If a vehicle with a locked open differential has its 4WD engaged and one wheel on each axle loses traction, it is stuck as neither axle will be able to function properly.

What do Differential Locks do?

The drawbacks to unlocked differentials are obvious. While they provide an invaluable service during normal driving conditions, unlocked differentials can lead to serious problems just when 4WD abilities are needed most. The best way to remedy this problem is with a differential lock. This type of lock inhibits the differential, allowing the drive power to be delivered to each wheel and axle equally.

Once you engage the differential lock, you’ll likely be able to maneuver out of most situations. The drawback is that differential locks are either engaged or not.

There’s no middle ground. In cases of extreme traction loss, as on ice, a differential lock can do more harm than good, so it must be used wisely.

Use Differential Locks Wisely!

The center differential lock that is necessary on full-time 4WD vehicles is prone to being used in a manner that produces excessive wear and tear. Make sure you’ve consulted the owner’s manual before you decide to get down and dirty in a full-time 4WD. If you engage a center differential lock on surfaces where it’s not needed, it can cause the differential to overheat, leading to failure.

Keep in mind that the lock is a fairly small part and it performs at a rate three or four times greater than the wheels in contact with the ground. When used as intended, it is one of the greatest traction systems ever; if it’s used when it’s not needed, it won’t last very long.