DIFFERENTIAL: Describes a unit that takes the power of the rotating drive shaft at right angles to the rear axle and passes it to the axle. The differential can drive both rear axles simultaneously while allowing them to rotate at different speeds while negotiating turns, preventing the vehicle's tires from skidding.

DIFFERENTIAL CAGE: Describes the rotating metal frame enclosing the differential side gears and pinion gears inside the axle casing

DIFFERENTIAL CASE: Describes the steel unit attached to the ring gear that drives the spider gears while forming an inner bearing surface for the axle and gears.

DIFFERENTIAL GEARS: Describes the gears that transmit engine power to the driving axles arranged to allow the rear wheels to turn at different speeds as required when the vehicle is turning.

DIFFERENTIAL LOCK:  Describes the mechanism eliminating the action of the differential so that both wheels can be driven for improved road grip on slippery surfaces.

DIFFERENTIAL PRESSURE: Describes the variations in pressure between the intake manifold and the atmospheric pressures.

DIRECTIONAL TREAD: Describes the arrangement of bars, grooves, and ribs on a tire's tread that provides the most effective traction when the tire revolves in only one direction.

AUTOMATIC SLIP-CONTROL DIFFERENTIAL(ASD): Describes an electronically controlled, automatic locking differential first developed by Mercedes-Benz.

FRONT DIFFERENTIAL: Describes the differential situated in the front axle of a four-wheel-drive vehicle.

HALF SHAFT: Describes a rotating shaft that transmits power from the final drive unit to one side of the drive wheels.

LIMITED SLIP DIFFERENTIAL: Describes the axle differential incorporating a slip-limiting mechanism to counter wheel spin. Limited slip means that a power level is always applied to each wheel, even when one is on a wet or icy surface, by transferring driving torque to another wheel.

LOCKING DIFFERENTIAL: Describes a differential capable of locking together the two half shafts, significantly improving traction.

LOCKUP DIFFERENTIAL: Describes a variety of differential whose two outputs can be locked together, maximising traction under slippery conditions.

LOW-SPEED TRACTION CONTROL: Describes the system that prevents front-wheel spin on slippery during acceleration at speeds of no more than 25 mph.

SPIRAL BEVEL GEAR: Describes a ring and pinion setup widely used in automobile differentials, where the teeth of both the ring and the pinion are tapered and cut on a spiral so that they sit at an angle to the centre line of the pinion shaft.

OPEN DIFFERENTIAL: Describes a standard system found on all conventional motor vehicles that operate using the primary drive axle differential function. An open differential cannot compensate for traction distinctions from one side of the vehicle to the other, meaning that the wheel with the least available grip is liable to spin.

REAR AXLE DIFFERENTIAL: Describes a form of differential found in a conventional rear-wheel-drive vehicle situated in the transmission assembly's final drive.

REAR DIFFERENTIAL: Describes a differential situated in the final drive of the transmission assembly in a conventional rear-wheel-drive vehicle

TORQUE SENSITIVE LIMITED SLIP DIFFERENTIAL: Describes a form of slip differential whose mechanism will react to variations in torque that occur when one wheel on an axle starts to slip.