The power unit is designed exclusivly for lifting the disabled people's wheelchair when they are getting in or off a certain type of vehicles. As a typical power up gravity down hydraulic system, It is composed of high pressure gear pump, hand pump, motor multi-functional manifold, valve, tank, etc. With the hand pump and the mannal override release valve, the power unit can is available. The counterbalance valve enables the tank, etc. With the hand pump and the mannal override release valve, the power unit can be operated ever if no electrical power is available. The counterbalance valve enables the wheelchair to lower smoothly.