In mechanical engineering terms, transmissions consist of a series of connected parts (or mechanisms) whereby a source of power can be applied to another component which is able do the required work in the form of motion.

Transmissions can be used to:

  • Connect two (or more) shafts so that one provides drive to another (or others).
  • Change the speed of one shaft relative to another.
  • Change the direction of rotation of one shaft relative to another.
  • Convert one type of motion to another (rotary to linear or vice versa).

Aerospace transmissions involve the use of a wide range of sources to provide the power, which eventually results in the desired motion in a particular system and those power sources include:

  • Muscle and assisted muscle power
  • Hydraulic, pneumatic and electrical power
  • External and internal combustion engines

The means of transmitting power from a source to provide eventual motion is achieved by such devices as:

  • Belts and Pulleys
  • Gears
  • Chains and Sprockets