Brand Hydraulics POR75-3/4 Pilot Operated Relief Valve

The Brand, pilot operated relief valve maintains the same cracking pressure at low and high flows. As the pressure setting is exceeded a poppet type relief opens and allows a small pilot supply of fluid to escape a chamber at the end of the main spool. The escape of pilot supply causes the main spool to shift and thus opens a passageway which allows the main volume of pressurized fluid to escape to tank without passing over the poppet type relief. The higher the pump output the farther the spool shifts over to enlarge the opening to tank.