SHIM-LINER 5S8145 - Caterpillar

Illustration 4 g00594007
Regulator Control ValveThe regulator control valve keeps the pump pressure and the pump flow at the level which is needed to fulfill the circuit load and the needs of the circuit flow. The regulator control valve regulates circuit load and circuit flow. The circuit load is regulated by sending pump oil to the lower actuator piston or by draining pump oil from the lower actuator piston. The actuator piston and the spring continuously adjust the angle of the swashplate. Pump outlet pressure is kept about 2100 kPa (305 psi) above work port pressure. The regulator control valve limits pressure in order to prevent overloading the pump and the system. When work port pressure goes over 16400 kPa (2380 psi), pressure compensator spool (32) will override the flow compensator spool and lower pump output.Low Pressure Standby
Illustration 5 g00632883
Regulator Control Valve at StandbyLow pressure standby occurs when the engine is running, and there are no flow demands or no pressure demands on the pump. At low pressure standby, there is no signal pressure in the port. When the engine is not running, the actuator spring holds the swashplate at the maximum angle. As the drive shaft begins to turn, flow in the circuit begins to increase. The pressurized pump oil enters the port passage. The pressure is felt by the flow compensator spool. The pressure is also felt by the pressure compensator spool. As pressure increases, the force of the pressure pushes the flow compensator spool upward against the spring. When pump pressure becomes greater than 2100 kPa (305 psi), the flow compensator spool will have moved up far enough to open the port passage to supply oil to the lower actuator piston. Providing oil to the lower actuator piston causes the actuator piston to act against the force of the spring. The lower actuator piston moves the swashplate toward the minimum angle. The actuator piston continues to move left until the piston uncovers the cross-drilled passage of the actuator piston. Uncovering the cross-drilled passage of the actuator piston allows the oil to drain to the case.The pump is now at low pressure standby. Low pressure standby is different from margin pressure. Low pressure standby is different due to circuit leakage and the cross-drilled hole in the lower actuator piston. At low pressure standby, the flow compensator spool must remain open in order to provide enough flow. The flow compensator spool creates an orifice. The oil flow past this orifice causes a drop in pressure. The flow is makeup for the oil that passed through the cross-drilled hole in the lower actuator piston. The cross-drilled passage in the actuator piston allows the oil to drain to the case. The oil pressure behind the actuator piston is less than circuit pressure but the force of the oil pressure is great enough to overcome the force of the spring.Note: Low pressure standby varies between different machines. Low pressure standby is not adjustable. Low pressure standby will vary within a pump as circuit