Differential gear, in automotive mechanics, gear arrangement that permits power from the engine to be transmitted to a couple of driving wheels, dividing the force equally between them but permitting them to check out paths of different lengths, as when turning a corner or traversing an uneven street. On a straight street the tires rotate at the same speed; when turning a part the outside wheel has farther to move and can turn faster compared to the inner steering wheel if unrestrained.
The components of the Ever-Power differential are proven in the Figure. The energy from the tranny is delivered to the bevel ring equipment by the drive-shaft pinion, both of which are held in bearings in the rear-axle casing. The case is an 
open boxlike framework that is bolted to the band gear possesses bearings to support a couple of pairs of diametrically reverse differential bevel pinions. Each wheel axle is mounted on a differential side equipment, which meshes with the differential pinions. On a straight road the tires and the side gears rotate at the same speed, there is no relative motion between the differential part gears and pinions, plus they all rotate as a unit with the case and ring gear. If the vehicle turns left, the right-hand wheel will be required to rotate faster than the left-hand steering wheel, and the medial side gears and the pinions will rotate relative to each other. The ring gear rotates at a quickness that is add up to the mean swiftness of the still left and correct wheels. If the tires are jacked up with the tranny in neutral and among the wheels is turned, the contrary wheel will turn in the opposite path at the same swiftness.
The torque (turning second) transmitted to the two wheels with the Ever-Power differential may be the same. Therefore, if one wheel slips, as in ice or mud, the torque to the other wheel is decreased. This disadvantage can be overcome somewhat by the utilization of a limited-slide differential. In one version a coupling China clutch connects one of the axles and the ring gear. When one wheel encounters low traction, its inclination to spin can be resisted by the clutch, thus providing higher torque for the various other wheel.
OPEN DIFFERENTIAL:
A differential in its most elementary form comprises two halves of an axle with a gear on each end, connected collectively by a third gear making up three sides of a square. This is generally supplemented by a fourth gear for added power, completing the square.