Differential gear, in automotive mechanics, gear arrangement that allows power from the engine to be transmitted to a set 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 road. On a straight street the coupling China wheels rotate at the same rate; when turning a part the outside wheel provides farther to move and will turn faster than the inner wheel if unrestrained.
The elements of the Ever-Power differential are demonstrated in the Figure. The energy from the transmission is sent to the bevel band equipment by the drive-shaft pinion, both which are kept in bearings in the rear-axle casing. The case is an open boxlike framework that is bolted to the ring gear possesses bearings to support a couple of pairs of diametrically opposite differential bevel pinions. Each steering wheel axle is mounted on a differential side equipment, which meshes with the differential pinions. On a straight road the tires and the medial side gears rotate at the same acceleration, there is absolutely no relative motion between the differential side 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 steering wheel will be forced 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 rate of the left and correct wheels. If the tires are jacked up with the transmitting in neutral and one of the wheels is turned, the opposite wheel will submit the opposite path at the same speed.
The torque (turning second) transmitted to the two wheels with the Ever-Power differential is the same. Therefore, if one steering wheel slips, as in ice or mud, the torque to the other steering wheel is decreased. This disadvantage can be overcome relatively by the use of a limited-slip differential. In one edition a clutch connects among the axles and the ring gear. When one wheel encounters low traction, its inclination to spin is definitely resisted by the clutch, therefore 
providing higher torque for the various other wheel.
OPEN DIFFERENTIAL:
A differential in its most basic form comprises two halves of an axle with a gear on each end, linked collectively by a third gear creating three sides of a sq .. This is generally supplemented by a 4th gear for added power, completing the square.