1. Walking low speed loop
The two-stage inclination angle of the walking motor of Sumitomo excavator is on the side of the large inclination angle. Even if the walking is switched to the high-speed side, the ignition switch is turned off and the ignition switch is turned on again, and the state will be restored to this state.
When the travel remote control valve is switched to the forward side, the pilot hydraulic oil is supplied to the control valve pal port, which switches the left travel slide valve to forward, and at the same time, hydraulic oil is also supplied to the pa6 port, which switches the right travel slide valve 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. The return oil flowing from the traveling motor during forward travel passes through the left and right traveling slide valves and returns to the hydraulic oil tank.
The walking high-speed solenoid valve is OF, the hydraulic oil of the Ps port of the walking motor is connected with the tank pipeline, and the inclination angle of the walking motor is turned to the inclination angle.
2. Walking high-speed loop
The walking high-speed 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 traveling motor is in a high-speed operation state, if load pressure is applied to the motor due to climbing, etc., the traveling motor has an automatic switching function that automatically switches to a low-speed state. When the traveling remote control valve is switched to the forward side, the pilot hydraulic oil is supplied to the control valve. The pal port switches the left travel slide valve to forward, and at the same time, hydraulic oil is also supplied to the pa6 port, which switches the right travel slide valve 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. Go ahead and walk.
The return oil flowing from the traveling motor passes through the left and right traveling slide valves and returns to the hydraulic oil tank.
By operating the walking high-speed switch, the electrical signal is transmitted to the controller, and then sent from the controller to the high-speed solenoid valve. By switching the high-speed solenoid valve, the pilot pressure (39MPa) from the C1 port enters the oil return ports of the left and right travel motors through the center joint, and adjusts the inclination angle of the travel motor to the side with a small inclination angle to increase the speed.
3. Straight-line 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, the left travel slide valve is switched to the forward side, and the hydraulic oil is also supplied to the pa6 port, and the right travel slide valve is switched to In addition, on the forward side, the right forward travel pilot hydraulic oil separated from the inside of the control valve pa6 port switches the straight travel signal (right).
The travel pilot hydraulic oil that flows out from the pal port and is diverted in the internal oil circuit, passes the linear travel signal (right), and switches the linear 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. Realize 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 to switch the boom (1) and (2) spool valves to the up side.
The pilot hydraulic oil of the upper body (boom, forearm, bucket, slewing, spare) separated from the pa4 port of the control valve is distributed to the linear travel valve through the linear travel signal (left), and the linear travel slide valve is switched.
The switching amount of the linear walking spool valve changes according to the pilot pressure of the upper body.
Note: When the upper body is operated under light load, 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, and the operation principle is the same when the actuators of the upper body except the boom are operated and the walking is maintained at the same time.
