Differential gear, in auto mechanics, gear arrangement that allows power from the engine to be transmitted to a set of generating wheels, dividing the force equally between them but permitting them to follow paths of different lengths, as when turning a corner or traversing an uneven road. On a straight street the tires rotate at the same quickness; when turning a corner the outside wheel has Differential Gear farther to proceed and can turn faster than the inner steering wheel if unrestrained.

The elements of the Ever-Power differential are shown in the Figure. The energy from the transmitting is sent to the bevel ring equipment by the drive-shaft pinion, both which are kept in bearings in the rear-axle housing. The case can be an open boxlike framework that’s bolted to the band gear and contains bearings to support a couple of pairs of diametrically opposite differential bevel pinions. Each steering wheel axle is attached to a differential side gear, which meshes with the differential pinions. On a straight road the tires and the side gears rotate at the same speed, there is absolutely no relative motion between the differential part gears and pinions, and they all rotate as a unit with the case and band gear. If the automobile turns to the left, the right-hand wheel will be required to rotate faster compared to the left-hand steering wheel, and the medial side gears and the pinions will rotate in accordance with each other. The ring gear rotates at a speed that is equal to the mean quickness of the left and right wheels. If the tires are jacked up with the transmission in neutral and among the tires is turned, the contrary wheel will submit the opposite path at the same speed.

The torque (turning minute) transmitted to the two wheels with the Ever-Power differential is the same. As a result, if one steering wheel slips, as in ice or mud, the torque to the other steering wheel is decreased. This disadvantage can be overcome somewhat by the use of a limited-slide differential. In one version a clutch connects one of the axles and the ring gear. When one steering wheel encounters low traction, its tendency to spin is resisted by the clutch, thus providing better torque for the additional wheel.
OPEN DIFFERENTIAL:
A differential in its most basic form comprises two halves of an axle with a gear on each end, connected collectively by a third gear creating three sides of a square. This is usually supplemented by a 4th gear for added power, completing the square.