- published: 10 Feb 2009
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A differential is a device, usually, but not necessarily, employing gears, which is connected to the outside world by three shafts, through which it transmits torque and rotation. The gears or other components make the three shafts rotate in such a way that Failed to parse (Missing texvc executable; please see math/README to configure.): \scriptstyle a=pb+qc , where Failed to parse (Missing texvc executable; please see math/README to configure.): \scriptstyle a , Failed to parse (Missing texvc executable; please see math/README to configure.): \scriptstyle b , and Failed to parse (Missing texvc executable; please see math/README to configure.): \scriptstyle c
. Except in some special-purpose differentials, there are no other limitations on the rotational speeds of the shafts. Any of the shafts can be used to input rotation, and the other(s) to output it. See animation here of a simple differential in which Failed to parse (Missing texvc executable; please see math/README to configure.): \scriptstyle p
Differential may refer to:
A gear is a rotating machine part having cut teeth, or cogs, which mesh with another toothed part in order to transmit torque. Two or more gears working in tandem are called a transmission and can produce a mechanical advantage through a gear ratio and thus may be considered a simple machine. Geared devices can change the speed, torque, and direction of a power source. The most common situation is for a gear to mesh with another gear, however a gear can also mesh a non-rotating toothed part, called a rack, thereby producing translation instead of rotation.
The gears in a transmission are analogous to the wheels in a pulley. An advantage of gears is that the teeth of a gear prevent slipping.
When two gears of unequal number of teeth are combined a mechanical advantage is produced, with both the rotational speeds and the torques of the two gears differing in a simple relationship.
In transmissions which offer multiple gear ratios, such as bicycles and cars, the term gear, as in first gear, refers to a gear ratio rather than an actual physical gear. The term is used to describe similar devices even when gear ratio is continuous rather than discrete, or when the device does not actually contain any gears, as in a continuously variable transmission.