Hydraulic drive for fast advance, working stroke and fast return - has valve in working piston operated against spring force by auxiliary piston

摘要

The piston rod space formed by the cylinder housing, working piston and working piston rod is provided with an inlet- and outlet opening. The pressurised medium connections and the inlet-and outlet openings are connected via a hydraulic control circuit in such a way that a valve can connect the inlet- and outlet opening with the working medium. The valve is fitted in the working piston and opens during return- and fast advance stroke by pressure in return space by action of an auxiliary piston against the force of a spring. Between the piston rod space and the return space a channel with a non return valve, which opens by pressure produced in the piston rod space during the working stroke.