A hydraulic power unit, or HPU for short, consists of four main components: a prime mover (either an engine or electric motor), a pump, a valve, and a reservoir. To choose the correct HPU you need to consider: horsepower of the power supply, a single or double acting valve, flow (GPM) of the pump, PSI of the system, and capacity of the tank. The rule of thumb is for every 1 HP you can provide 1 GPM flow at 1500 PSI. The tank of your power unit is sized based on the capacity of your cylinder. Review each component below to learn more.