What Is a Differential on a Semi Truck?

A Differential is a crucial part of the drive system of a semi truck. It is responsible for the transmission of power from the engine to the wheels, while allowing the wheels to turn at different speeds. This is important when turning, as it allows each wheel to turn at its own rate, rather than have both wheels turning at the same rate – which can cause major damage to your truck’s drivetrain.

The differential works by using two sets of gears that are connected in an “X” shape. The two gears – called pinion gears – are connected by a third gear called a crown wheel gear.

When the engine is running, power from the engine is transferred to this crown wheel gear. This power is then transferred through both pinion gears, which then turn the two drive wheels at different speeds.

The differential helps in maximizing traction and providing stability during high-speed cornering. Without it, one wheel would slip or spin faster than the other when cornering or going over uneven terrain. This could cause excessive tire wear or even loss of control.

Differentials are also used in semi trucks to help with braking performance. As one wheel brakes harder than another, the differential compensates by transferring more power to that wheel so it can slow down along with its partner wheel.

Differential gearing has been around for many years and has evolved significantly over time. Today’s semi trucks use differentials with helical gearing and limited slip capabilities which further enhance their performance on roads and highways.


A differential on a semi truck is an essential component that helps transfer power from the engine to its drive wheels while allowing them to rotate at different speeds for maximum traction and safety when cornering or going over rough terrain. Differentials have evolved significantly over time and now feature helical gearing and limited slip capabilities for enhanced performance on roadways.

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Susan Delgado