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 travel spool is in neutral, the travel motor stops, and when the travel joystick (pedal) is moved forward or backward, the travel motor also rotates accordingly to drive the machine forward or backward. By operating the travel control valve, the pilot pressure line is closed, and the boost signal loosens the main relief valve to increase the travel pressure.
(1) Linear travel function only when the travel spool is working
The pressure oils of pumps A1 and A2 move the machine forward through the left and right walking motors as shown in Figure 3-7. 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 preferentially supplied to the rotary 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 simultaneously.
(2) High-speed, medium-speed and low-speed walking
By pressing the walking mode selection switch on the compound 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 speed travel. At low speeds, the pressure oil flow of the travel motor is converted to low travel speed. When set to high speed, the pressure oil of pump A1 and pump A2 is controlled by APC100 system through the pressure sensor. If the rated high-speed pressure is exceeded, the travel speed solenoid valve is switched to the OFF position, the pilot pressure is cancelled and the travel is switched to medium speed, which generates a large torque. When the rated pressure is lower than the travel speed solenoid valve is switched to the "ON" position And the pilot pressure is restored to the high-speed position.
