When fitting the valves to control blocks and housings, the recommended torque ratings must be observed. during hose breaks or pump failure Applications are for example: injection moulding machines lifting platforms support cylinders mobile hydraulics hydraulic tensioning handling devicesĢ.1.1 Designation and symbol Pilot-operated check valve press cylinders prevention of uncontrolled movement of loaded appliances, e.g. Therefore there must be no pressure across port 2 during the hydraulic cancellation of the shut-off function.ĪPPLICATION HYDAC pilot-operated check valves, type ERVE, are suitable for: prevention of creeping movement of loaded cylinders which are operated by spool valves shut-off or cancellation of pressurised units, e.g. On the control piston, the pressure across port 2 counteracts the control pressure across port 3. Due to the further stroke of the control piston the main stage is then opened and flow can go from 1 to 2. By introducing a sufficiently high control pressure across port 3 (see 2.2.10) the seat of the first stage is opened this leads to a damped relief of the pressurised fluid. In the opposite direction, the ball and the cone piston are pushed against the seats by the closing spring and the pressure across port 1 the connection from 1 to 2 is shut-off leakage-free. #Mainstage 2.2.1 download for free#For free flow from 2 → 1, the main stage and the first stage are pushed simultaneously against the closing spring and therefore clear the necessary cross section on the seat of the main stage. Valve body control piston return spring seat main stage seat first stage ball cone piston closing springġ.2.2 ERVE-R 1 and ERVE-R 1 ½ (two-stage) HYDAC pilot-operated check valves, size ERVE R 1 and ERVE R 1 ½, are valves with first stage decompression. Therefore there must be no pressure across port 2 during the hydraulic cancellation of the shut-off function. On the control piston the pressure across port 2 counteracts the control pressure across port 3. The return spring fitted underneath the control piston allows an inertialess return if pressure is released across control port 3. By introducing a sufficiently high control pressure across port 3 (see 2.2.10) the control piston is moved and the ball is pushed away from the valve seat the shut-off function is cancelled and flow can go from 1 → 2. In the opposite direction the ball is pushed against the valve seat by the closing spring and the pressure across port 1 and shuts off the flow in direction 1 → 2 leak-free. Valve body control piston return spring valve seat ball closing springġ.2.1 ERVE-R ½ (direct operated) HYDAC pilot-operated check valves, size ERVE R ½, are direct operated ball seat valves for oilhydraulic systems. Advantages are: leak-free in shut-off direction 1 → 2, the appliances are kept in position compact construction enables mounting into cylinders, housings etc three sizes for a range of different applications 2 sizes with two-stage operation to avoid shocks during the relief of pressurized fluids inline housings are available for all sizes OPERATION HYDAC pilot-operated check valves, type ERVE, size R ½ are direct operated, and size R 1 and R 1 ½ are two-stage. Due to the seat valve construction, the valve is leakage-free in the shut-off position. GENERAL In accordance with DIN-ISO 1219, HYDAC pilot-operated check valves, type ERVE, are check valves for oilhydraulic systems, on which the shut-off function can be cancelled hydraulically.
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