Hi –Low Circuit/Block
This assembly allows the smooth unloading of a low-pressure / high-flow pump in a 2 pump high-low system. This type of system utilizes the flow of 2 pumps to provide rapid speed to an actuator. Once resistance is encountered, and the requirement switches from high speed to high force / torque, then the low-pressure / high-flow pump is unloaded back to tank at minimum pressure and all the available horsepower is directed to the high-pressure / low-flow pump. This assembly also provides a system relief valve.
The counterbalance valve in this assembly is not acting as a counterbalance valve; it is acting as a pressure sensitive unloading valve. The setting, however, relates to the counterbalance world. With the CB*A set at 4000 psi (280 bar), the circuit will start to unload with about 1000 psi (70 bar) of pressure and will fully unload somewhere above 1400 psi (90 bar).
⦁ Turn adjustment clockwise to decrease setting of the counterbalance valve.
⦁ Backpressure at port 2 of the counterbalance valve adds to the effective relief setting at a ratio of 1 plus the pilot ratio times the backpressure.
⦁ Counterbalance valve reseat exceeds 85% of set pressure when the valve is standard set. Settings lower than the standard set pressure may result in lower reseat percentages.
⦁ Back pressure on the tank port (port 2) of the relief valve is directly additive to the valve setting at a 1:1 ratio.