Whilst embracing a similar technology to generator sets, APU’s are vehicle specific and require expertise to mechanically and electrically integrate into the application. Their main attribute is the provision of electrical power and other supplies, such as compressed air, when the vehicle is stationary and under silent watch conditions.

A typical example is the Challenger APU, which provides 10kW of electrical power plus a hydraulic supply in its CRARRV form and originally included a 4kW compressed air supply.

The unit depicted is a 3kW size APU used on the UK MLRS vehicle which is fitted inside an acoustic enclosure for additional signature suppression.