• A pressure-compensated variable-displacement pump is equipped with a pressure compensator or "cutoff" valve to reduce output flow when a preset pressure level is achieved.
• The level is adjusted by the spring of the pressure compensator.
• The pump provides maximum flow if pressure in the system is below this level.
• The pump output flow decreases as soon as the preset pressure level is overcome.

Standby mode

Initiate. When there is no load in the system the pump output flow is maximal. The pump output pressure in the system is determined by internal components resistance, mainly by the lines themselves. Under these conditions, the pressure is pretty low.

Close 1/2

Initiate. The load can be imitated by the adjustable restrictor. As this restrictor closes the pump output pressure rises. The maximum of the pump output pressure is limited by the setting of the pressure compensator or "cutoff" valve. Cutoff pressure is adjusted by the spring on this valve.

Close to Δ p range

Initiate. When the output pressure reaches the cracking pressure value, then the pressure compensator moves right to open the channel to the control piston. The output flow starts to decrease. It leads to a decrease of the pressure level before the restrictor. When the pressure drops, the spring of the "cutoff" valve returns the valve to the left position. So, the channel to the control piston closes and the bias spring pushes the swash plate to increase the pump output flow. The pressure level before the restrictor starts to increase and the process repeats.

Close completely

Initiate. When the restrictor is completely closed, the pump output pressure increases until it overcomes the "cutoff" valve preset value. As a result the pump displacement decreases to the minimal volume to provide the flow level required for cooling, compensation of internal leakages and lubrication purposes, only. The swash plate should not reach a neutral position. This can be realized either with a mechanical restrictor or with an orifice inside the control piston. The orifice opens a way for oil to flow out of the control piston when the swash plate moves closer to the neutral position. Opening the way for oil causes a pressure drop. The pump displacement stops decreasing.

Pressure adjustment

Initiate. To adjust the cutoff level, the spring force must be set when the restrictor is completely closed.Cancel animation.