Bosch Rexroth SL20PA1-4X/M subplate pilot-operated check valve

Bosch Rexroth SL20PA1-4X/M is a size 20 hydraulically released check valve for subplate mounting, factory article R900587559. It allows spring-loaded flow from A to B and blocks reverse flow until adequate hydraulic pilot pressure at X opens the valve. The SL execution uses an external pilot-oil drain at Y.

The A execution includes decompression to relieve a pressurised volume before full opening. The July 2005 reference curves give 2.5 bar opening pressure in the free-flow direction for spring code 1, measured with HLP46 oil at 40 ± 5 °C. This is not the required pilot pressure: pilot demand depends on load pressure, return pressure and the opening-force balance.

The supplied article identity is confirmed by the manufacturer’s material-number lookup. The technical reference is the manufacturer’s July 2005 4X document; current execution-specific maximum pressure, flow and seal-dependent temperature limits require confirmation and are not presented as current ratings. The /M factory suffix is retained without assigning an unconfirmed seal material. Subplates and fixing screws are ordered separately. The manufacturer series photograph is representative; drainage and decompression details must be checked against the selected symbol and drawing.