Hydraulic
The engine generally has a hydraulic pump mechanically driven by the engine, but there may also be electrically driven pumps.
In passenger cars, the most common use of hydraulic power has been the steering system. Convertible tops may be raised and lowered using hydraulics. Windshield wipers were sometimes hydraulically driven, although this use mostly ceased after the late 1960s. On vehicles with little or no engine vacuum, hydraulic systems are generally adopted in place of vacuum systems.
The French company Citroën devised a high-pressure hydraulics system for cars which was used for all manner of systems, even power-adjustable seats.
The 1999-2004 Jeep Grand Cherokee had a hydraulically-driven radiator fan, powered by the SUV's power steering pump.
In vehicles such as heavy trucks and tractors, hydraulic systems are much more common. Hydraulic rams are used for accessories such as dump truck beds, cranes, loaders, and three-point hitches.
Read more about this topic: Automobile Accessory Power