SYSTEM / Control System Auto-Power Lift Control Purpose: Increases pressure when raising the boom. Operation: 1. MC activates solenoid valve unit (SG) when the signals from pressure sensors (boom raise, arm roll-in) and pump 1 delivery pressure sensor meet the following conditions. 2. Pressure oil from the pilot pump flows to the back of main relief valve. 3. Pressure oil compresses the spring of main relief valve and increases relief pressure (Refer to the Control Valve group / COMPONENT OPERA- TION.) Conditions: Boom Raise Pressure Sensor: Output 1.7 MPa (17 kgf/cm 2 , 247 psi)) or higher Pump 1 Delivery Pressure Sensor: Output 29 MPa (295 kgf/cm 2 , 4220 psi) Arm Roll-In Pressure Sensor:
Output zero. (0.5 MPa (5.1 kgf/cm 2 , 73 psi)) NOTE: This control system is activated during combined operations (except for the arm roll-in combined operation). T2-2-46