1. Walking low-speed loop
The two-stage tilt angle of the Sumitomo excavator's walking motor is the side with a large tilt angle. Even if the walking is switched to the high-speed side, after the ignition switch is turned off, and the ignition switch is turned on again, it will return to this state.
When the travel remote valve is switched to the forward side, the pilot hydraulic oil is supplied to the pal port of the control valve to switch the left travel spool to forward, and at the same time, hydraulic oil is also supplied to the pa6 port to switch the right travel spool to forward The hydraulic oil discharged from the A1 port of the hydraulic pump enters the P1 port of the control valve, and the hydraulic oil discharged from the A2 port of the hydraulic pump enters the P2 port of the control. Forward travel The return oil flowing from the travel motor passes through the left and right travel slide valves and returns to the hydraulic oil tank.
The travel high-speed solenoid valve is OF, the hydraulic oil of the travel motor Ps port is connected to the oil tank line, and the tilt angle of the travel motor turns to the tilt angle travel low-speed circuit
2. Walking high-speed loop
The high-speed walking circuit converts the two-stage inclination angle of the walking motor into a small inclination angle to make it run at high speed. When the travel motor is in a high-speed running state, if load pressure is applied to the motor due to climbing, etc., the travel motor has an automatic switching function that automatically switches to a low speed state. When the travel remote valve is switched to the forward side, the pilot hydraulic oil is broken and supplied to the control valve The pal port switches the left travel spool to forward. At the same time, hydraulic oil is also supplied to the pa6 port to switch the right travel spool to the forward valve.
The hydraulic oil discharged from the A1 port of the hydraulic pump enters the P1 port of the control valve, and the hydraulic oil discharged from the A2 port of the hydraulic pump enters the P2 port of the control, and flows to the travel motor through the switching of the left and right travel slide valves, respectively, to achieve Go forward.
The return oil flowing from the travel motor passes through the left and right travel slide valves and returns to the hydraulic oil tank.
By operating the walking high-speed switch, the electrical signal is transmitted to the controller, which in turn sends it to the high-speed solenoid valve. Through the switching of the high-speed solenoid valve for travel, the pilot pressure (39MPa) from the C1 port enters the return ports of the left and right travel motors through the center joint, and the tilt angle of the travel motor is adjusted to the side of the small tilt angle to increase the speed.
3. Linear walking circuit
When the travel remote control valve is switched to the forward side, the pilot hydraulic oil is supplied to the control valve pa port to switch the left travel spool valve to the forward side, while hydraulic oil is also supplied to the pa6 port to switch the right travel spool valve to On the forward side, the right forward travel pilot hydraulic oil separated from inside the control valve pa6 oil port switches the straight travel signal (right).
The traveling pilot hydraulic oil that flows out of the pal oil port and shunts in the internal oil passage passes the straight travel signal (right) and switches the straight travel signal (left).
The hydraulic oil discharged from the A1 port of the hydraulic pump enters the P1 port of the control valve, and the hydraulic oil discharged from the A2 port of the hydraulic pump enters the P2 port of the control valve, and flows to the travel motor through the switching of the left and right travel slide valves, respectively. Achieve forward walking.
When the boom is raised during walking, the pilot hydraulic oil passes through the damping valve and is distributed to the control valve pa4 oil to switch the boom (1) and (2) spools to the rising side.
The pilot hydraulic oil of the upper body (boom, arm, bucket, swing, standby) separated from the inside of the control valve pa4 oil port is distributed to the linear travel valve through the linear travel signal (left) to switch the linear travel slide valve.
The switching amount of the linear travel slide valve changes according to the pilot pressure of the upper body.
Note: When the upper body is under light load operation, due to the low pilot pressure, the switching amount of the linear travel slide valve is small, which can prevent the travel speed from suddenly decreasing.After the linear travel valve is switched, the hydraulic oil of the control valve P1 can drive the left and right travel motors. The hydraulic oil of the control valve P2 can drive the boom. The left and right motors are driven by a hydraulic pump, so the pressure of the left and right motors is the same, which can maintain straight travel. When operating the upper body actuators and walking at the same time, the operating principles are the same.
