In a circuit which uses two parallel pumps, this valve unloads the larger pump to tank once the pressure setting of BP has been reached. From this point the circuit will only be supplied by the smaller pump at a higher pressure AP, therefore consuming less energy. The valve body has been designed for direct flange mounting onto the low flow pump. To limit the pressure of the high flow pump use an inline relief valve or the main relief valve on the spool valve.
Zinc-plated steel with internal parts in hardened and ground steel
Flange BP onto the higher flow pump, connect AP to the lower flow pump, T to the tank, M to the eventual manometer and U to the hydraulic circuit.