The locking differential functions as a regular or open differential but has
the ability to lock the shafts leading to the two wheels on an axle together and forces them to rotate at the same speed.
Both wheels are therefore operating as if were on a single shaft.
The locking differential is the superior alternative for off road manoeuvres as both wheels spin with equal force regardless
of which wheel receives the power and that wheel can move the vehicle out of a sticky situation. This is opposed to a
limited slip differential which is mainly used to direct torque
to the wheel with the most traction to achieve better handling and performance in on road driving.
A locking differential is designed to be used in difficult situations during off road driving as it is not constantly
locked. There is a switch to lock the differential for off road driving and to unlock it for regular asphalt driving. A
locking differential should never be locked once the vehicle is being driven on a paved road and it may not be required to
be locked on light off roading.
The reason the differential can't be permanently locked during regular driving is because the left and right
wheels on the same axle rotates at different speeds during cornering because the outer wheel has more distance to
cover and a locked differential forces both wheels to rotate at the same speed. If both of the wheels have adequate
traction the outer wheel will slip and this puts a strain on the vehicle or the
transmission may be damaged.
When driving off road in low traction conditions the locking differential works well as in many occasions one
of the wheels may not have much traction and can easily spin together with the wheel with the grip. The ground in off
road conditions usually consist of mud, sand, grass or loose particles such as gravel so if a wheel has to slip it can
slip without putting any pressure on the vehicle.
It is common for a dedicated off road vehicle to have three differentials and all three can be locking differentials.
Once the vehicle is an four wheel or all wheel drive there will naturally be a differential
for the front and rear axles and the third differential will be along the driveshaft between the front and rear axles as the
front and rear wheels also cover various distances during cornering.
A 4WD vehicle without a center differential will be a part time four wheel drive as the vehicle will have to remain
in two wheel drive for on road driving. If a vehicle is a part time four wheel drive then 4WD should only be selected when
the vehicle is being driven off road as the front and rear wheels will rotate at the same speed because the driveshaft
without a center differential is the equivalent of having a constantly locked differential.
A locking differential can be mechanical or electronic. An electronic locking differential may be automatic and lock both
shafts automatically if the vehicle senses that one wheel has no traction and unlock them with traction is detected at both wheels.