Differential gear, in automotive coupling China 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 street. On a straight road the tires rotate at the same speed; when turning a part the outside wheel provides farther to go and will 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 held in bearings in the rear-axle housing. The case is an open boxlike framework that is bolted to the band gear possesses bearings to support one or two pairs of diametrically opposing differential bevel pinions. Each steering wheel axle is attached to a differential side equipment, which meshes with the differential pinions. On a straight road the wheels and the side gears rotate at the same quickness, there is no relative motion between your differential part gears and pinions, and they all rotate as a unit with the case and band gear. If the vehicle turns to the left, the right-hand wheel will be required to rotate faster compared to the left-hand wheel, and the medial side gears and the pinions will rotate relative to one another. The ring gear rotates at a speed that is equal to the mean speed 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 path at the same speed.
The torque (turning moment) transmitted to both wheels with the Ever-Power differential is the same. Consequently, if one wheel slips, as in ice or mud, the torque to the other wheel is decreased. This disadvantage could be overcome relatively 
by the use of a limited-slide differential. In one version a clutch connects among the axles and the band gear. When one wheel encounters low traction, its inclination to spin is definitely resisted by the clutch, hence providing better 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, linked with each other by a third gear creating three sides of a sq .. This is usually supplemented by a 4th gear for added power, completing the square.
This basic unit is then further augmented by a ring gear being added to the differential case that holds the basic core gears – and this ring gear allows the wheels to be powered by connecting to the drive shaft with a pinion.