Trade assurance HUADE Hydraulic control one-way valve SV10PA-1-30  SV30PA-1-40B

product manual:
SV and SL type hydraulic control one-way valves are seat valves that can be opened by hydraulic pressure to allow reverse flow. This type of valve is used to isolate the local pressure loop, which is to prevent the load from landing when the pipe breaks, and also to prevent the load from climbing down.
This kind of hydraulic control valve mainly includes the valve body, the main valve core, the pilot valve core, the compression spring and the control piston.
SV type (no drain)
Flow is always free from port A to port B, with the reverse direction keeping the pilot and main spool on the seat by spring and system pressure. If X port supply pressure oil, the control piston is pushed to the right. First open the pilot valve center, and then open the main valve core. So the oil first through the guide valve, then through the main valve. In order to ensure that the control piston can operate the valve as possible, a certain amount of pressure control is required.
SL type (with drain)
In principle, this valve has the same function as the SV type. The difference is that the drain port Y is increased, which isolates the circulation area of the piston from port A. The oil pressure from port A ACTS only on the control piston area A4, thus effectively reducing the control force required under this condition.