Differential gear, in auto mechanics, gear arrangement that allows power from the engine to be transmitted to a couple of traveling 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 
street. On a straight road the wheels rotate at the same swiftness; when turning a corner the outside wheel provides farther to go and can turn faster compared to the inner steering wheel if unrestrained.
The components of the Ever-Power differential are shown in the Figure. The energy from the transmission is sent to the bevel band equipment by the drive-shaft pinion, both which are held in bearings in the rear-axle housing. The case can be an open boxlike framework that's bolted to the ring gear and contains bearings to support a couple of pairs of diametrically opposing differential bevel pinions. Each wheel axle is attached to a differential side equipment, which meshes with the differential pinions. On a directly road the tires and the side gears rotate at the same velocity, there is no relative motion between the differential part gears and pinions, and they all rotate as a unit with the case and ring gear. If the automobile turns to the left, the right-hand wheel will be forced to rotate faster than the left-hand wheel, and the side gears and the pinions will rotate in accordance with one another. The ring equipment rotates at a swiftness that is equal to the mean velocity of the remaining and right wheels. If the wheels are jacked up with the tranny in neutral and among the wheels is turned, the opposite wheel will turn in the opposite direction at the same acceleration.
The torque (turning instant) transmitted to both wheels with the Ever-Power differential is the same. Therefore, if one wheel slips, as in ice or mud, the torque to the other steering wheel is reduced. This disadvantage can be overcome somewhat by the utilization of a limited-slip differential. In one edition a clutch connects one of the axles and the band gear. When one steering wheel encounters low traction, its inclination to spin can be resisted by the clutch, thus coupling China providing higher torque for the additional wheel.
OPEN DIFFERENTIAL:
A differential in its most elementary form comprises two halves of an axle with a equipment on each end, connected together by a third equipment creating three sides of a square. This is generally supplemented by a 4th gear for added power, completing the square.