A hydraulic jack creates pressure by moving oil through two cylinders via a pump plunger. The pump plunger is drawn back, which opens the suction valve and draws oil into the pump chamber. As the plunger is pushed down, the oil is transported through an external discharge valve and into the cylinder chamber. The suction valve then closes, resulting in pressure being built up within the chamber; causing the piston in the chamber to rise and lift your heavy object. We keep both Integral as well as Remote control type jacks in our inventory. Capacities ranging from 5 tons upto 500 tons.