The pressure oil of the pump A1 drives the left travel motor through the spool 1 of the control valve (valve block A), and the pressure oil of the pump A2 drives the right travel motor through the spool 1 of the control valve (valve block B). When the walking spool is in neutral, the walking motor stops. When the walking joystick (pedal) is moved forward or backward, the walking motor also rotates correspondingly to drive the machine forward or backward. By operating the walking control valve, the pilot pressure pipeline is closed, the boost signal loosens the main relief valve, and the walking pressure rises.
(1) The straight-line walking function is only when the walking spool is working
The pressure oil of the pumps A1 and A2 respectively pass the left and right travel motors to make the machine move forward, as shown in Figure 3-7. When the travel spool and other operations work together, such as the rotation and travel spools work at the same time, the pilot of the travel and the upper turntable The signal path is closed, and the pilot pressure generated can always be on the linear travel valve.
The pressure oil of the pump A1 is given priority to the slewing device, and the pressure oil of the pump A2 flows into the left and right travel motors so that the linear travel and other operations can be performed at the same time.
(2) High-speed, medium-speed and low-speed walking
By pressing the walking mode selection switch on the composite monitor, 3 different walking speeds can be selected. By opening and closing the travel speed solenoid valve, the pilot pressure changes the swash plate angle of the travel motor, resulting in medium and high travel speeds. At low speeds, the pressure oil flow of the travel motor is converted to a low travel speed. When set to high speed, the pressure oil of pump A1 and pump A2 is controlled by the APC100 system through the pressure sensor. If the rated high-speed pressure is exceeded, the walking speed solenoid valve will be switched to the OFF position, the pilot pressure will be cancelled and the walking speed will be switched to medium speed, resulting in large torque. When the pressure is lower than the rated pressure, the walking speed solenoid valve will be switched to the “ON” position , And generate the pilot pressure to return to the high-speed position.
