Automobile Differential Gear Train |

The gearing of an automobile differential is illustrated as following in final form. Automobile Differential Complete Schematic
Without the "square" set of four gears in the middle of the above diagram which yields to the figure below, both wheels turn at the same angular velocity. This leads to problems when the car negotiates a turn. Automobile Wheel Drive without Differential
Now imagine the differential "square" alone, as illustrated in the following figure. It should be apparent that turning one wheel results in the opposite wheel turning in the opposite direction at the same rate. Automobile Differential Alone
This is how the automobile differential works. It only comes into play when one wheel needs to rotate One problem with an automotive differential is that if one wheel is held stationary, the counterpart wheel turns at twice its normal speed as can be seen by examining the complete scheme of automobile differential. This can be problematic when one wheel does not have enough traction, such as when it is in snow or mud. The wheel without traction will spin without providing traction and the opposite wheel will stay still so that the car does not move. This is the reason for a device known as a "limited slip differential" or "traction control". |

Differential Gear Train on a Turning Car |

The gear train in an automobile differential is a common application of gears, but often misunderstood by the lay public. Here we present a simplified explanation of how and why an automobile differential works. The car is turning about a circle with nominal radius r The outer wheel traverses an arc with radius r Since s=r(THETA), the length of the arc traversed for a given theta is proportional to the radius. Since r |