Forhjulsdifferential

Forhjulsdifferential, or front differential, is a mechanical device that distributes engine torque to the front wheels while allowing them to rotate at different speeds. It is typically located in the front axle assembly and is standard on most front-wheel-drive vehicles. In all-wheel-drive layouts, a front differential forms part of the transaxle or front drivetrain and works in concert with a center differential to balance torque between the front and rear axles.

Function and operation: The differential contains a set of gears—side gears attached to the front half-shafts and a spider or pinion gear set inside a differential carrier. This arrangement permits the front wheels to turn at different speeds, which is necessary during steering and suspension movement. When both front wheels have similar grip, torque is distributed in roughly equal amounts. If one wheel experiences less traction, an open differential tends to transfer more torque to the wheel with less grip, which can reduce propulsion in slippery conditions.

Variations: The most common type is the open differential. Limited-slip differentials (LSD) use clutches, viscous couplings, or electronic control to limit differential action and improve traction. Locking differentials may mechanically lock the two front wheels together for improved traction in low-traction or off-road situations, though they are less common on modern road cars.

Maintenance and issues: Front differentials require gear oil of the specified grade and level. Regular maintenance intervals vary by manufacturer. Symptoms of trouble can include unusual noises, leaks, or uneven tire wear, which may indicate worn gears, bearings, or seals.

Related concepts include center differentials, transaxles, and all-wheel-drive systems.