An air compressor is not necessary to operate QuickJack. The portable power unit is electric over hydraulic and contains a built-in flow divider that ensures equal fluid pressure is given to both cylinders. No air required. There is a secondary "air spring" cylinder that helps QuickJack lower smoothly to the ground when there is no weight on the frames. This cylinder needs to be filled to 40-50 psi during setup and rarely needs to be refilled.