The car differential is a mechanism that enables the left and right (or front and rear) drive wheels to rotate at different speeds. It is mainly composed of left and right half-shaft gears, two planetary gears and a gear rack. The function is to make the left and right wheels roll at different speeds when the car is turning or driving on uneven roads, that is, to ensure that the drive wheels on both sides are in pure rolling motion. The differential is installed to adjust the speed difference between the left and right wheels. In four-wheel drive, in order to drive the four wheels, all wheels must be connected. If the four wheels are mechanically connected together, the car cannot rotate at the same speed when driving in a curve. In order to make the car's rotation speed basically consistent when driving in a curve, an intermediate differential needs to be added to adjust the speed difference between the front and rear wheels. The most widely used one at present is the symmetrical bevel gear differential.
If there is no differential on your car, the two wheels will be rigidly fixed together and rotate at the same speed. When the car is turning, the wheels will inevitably roll and slide. This will accelerate tire wear, increase the power consumption of the car, and put a lot of stress on the axle. In order to ensure that the driving wheels on both sides are always in a pure rolling state, people use two half-axles to connect the wheels on both sides respectively, and the driven wheels of the main reducer drive the half-axles and wheels on both sides through the differential, so that they can rotate at different angular velocities.
However, the differential also brings certain side effects. That is, when one of the two wheels has a large resistance, the output power is all concentrated on the other wheel, resulting in only one wheel idling. It is common to see wheels stuck in mud and snow.
Therefore, in order to cope with this weakness of the differential, many high-performance cars and off-road vehicles are equipped with differential locks, using mechanical or electronic locking methods.
When the driving wheels of the car lose adhesion, the differential is weakened or loses the differential effect, and the power is evenly distributed to the driving wheels to help the vehicle get out of trouble. This is what we often call a differential lock. Common differential locks are tooth-type and multi-plate clutch types, and the control methods are manual operation, torque sensing control and electronic hydraulic control. The Torsen differential is an exception. It has a built-in differential locking function and does not require a special control mechanism. It is generally used as a central differential.