With compressed air they can rev up another machine to the starting speed. Compressed air is converted into motion via a pinion and the rotation is transmitted to a ring gear to start up the engine or turbine.
 

Air Starters - Applications

Air starters can be applied at each location where compressed air or other starting gas is present at high pressure in a reasonable amount. While this start method requires a larger installation lineup. It is a very reliable and clean method of starting up compared to electric starting. In industrial applications one tends to consume and replace a lot of batteries in order to keep the starting capability reliable. With TDI starter motors you only need one vessel with compressed air standing by and normally this air supply is dimensioned that multiple starts can be made before the tank is empty. Air Starters are often used in locations under hazardous environmental conditions. In environments where people work with flammable substances is an example where air starters are often used. This way high start-up currents coming from the batteries can be avoided. On ships, air starters are often applied so that the engine can still be started up, even when the entire electric circuit on the ship has broken down.

Air Starters can also be found on large mining trucks in day mining locations, on gas turbines and gas engines used in power generation and oil and gas applications.