The differential, as its name implies, is something that makes the wheels on both sides produce a speed difference. When the vehicle turns, the rotation speed of the outer wheel is greater than that of the inner wheel, and the speed difference caused by the different rotation speed is balanced by the differential.

The differential mainly relies on the meshing between the planetary gear and the sun gear to freely distribute the power from the input shaft to the wheels on both sides, which side has the lower wheel resistance, the power will be more distributed to which side. In other words, when one wheel is idling and the other wheel is not spinning, the wheel on the idling side will be allocated nearly 100% of the power, doing useless work, which is what we often call slipping and idling.

In order to prevent the wheels on one side from spinning and the wheels on the other side that really need power are allocated enough power, engineers thought of using a differential lock to solve this problem.

● Differential lock

The differential lock, as the name suggests, is used to lock the differential speed of the wheels. When one wheel is idling, resulting in a loss of power, the differential lock can make a "hard" connection between the wheels on both sides. When the differential lock is locked, you can think of the locked drive axle as a whole connected by a hard steel pipe. At this time, the speed of the wheels on both sides is forcibly equal, that is, if the wheel on the left rotates by one Circle, the wheel on the right should also rotate a circle, so that the wheel on the ground side can get enough power to help the vehicle get out of trouble smoothly.

For trucks, the most common differential lock is the "jaw-type" differential lock shown. When the differential lock is locked, the drive shaft is fixed (engaged) by a tooth-like gear to achieve the lock. The effect of stopping, so that the vehicle can get out of trouble smoothly. This is also a relatively more stable and reliable differential lock form at this stage.

The differential lock is not like a gearbox with a synchronizer. The speed of the jaw gears on both sides will not be automatically synchronized. Therefore, before using the differential lock, you have to stop the vehicle and then turn on the differential lock.