1. Rotary parking brake system
When the front boom, forearm and other accessories are lifted off the ground when parking on a slope, if oil leaks in the rotating circuit, the upper structure may move due to its own weight. There is a rotary parking brake inside the machine to prevent such movement.
2. Release the rotary parking brake
Use the pilot oil pressure of the pilot oil pump to release the rotary parking brake as shown in Figure 2-18. When performing a rotating operation or a backhoe operation, the pressure switch in the pilot circuit sends the sensing signal to the PVC, and the PVC instructs the proportional solenoid valve to open the oil circuit to operate the rotary parking brake.
The pilot oil pressure overcomes the force of the brake spring through the proportional solenoid valve to open the brake piston and release the brake function.
3. The rotating parking brake works
When the machine is performing operations other than rotating operation and forearm backhoe operation, the pressure switch in each pilot circuit sends the sensing signal to the PVC, and then sends the control signal to the proportional solenoid valve, and the brake piston is driven by the proportional solenoid valve The oil circuit is closed. When the pilot oil pressure acting on the brake cylinder is released back to the fuel tank, the brake spring pushes back the brake piston, and the parking brake is activated by rotating it, as shown in Figure 2-19. The car only works.
4. Warm-up control system
When the hydraulic oil temperature is lower than 30℃ to start the engine, the engine speed will increase and the pump output oil will be automatically reduced, thus effectively heating the engine and hydraulic system.
Figure 2-20 shows the control of stepwise warm-up over time.
As soon as the warm-up switch is turned on, PVC receives the sensing signal that the hydraulic oil temperature is lower than 30°C, and PVC sends the control signal to the EC motor through EC, so that the engine speed is 10% (1min) faster than the slow speed.
After 1min, the engine speed increased by 30%, and the pump flow rate also increased by approximately 6% (15min) of the minimum flow rate. After 16min or when the hydraulic oil is warmed to 30℃, the warm-up operation ends automatically. When the power mode switch is selected in a position other than the L mode during the warm-up operation, the engine speed also changes with the position of the power mode switch, but the swash plate of the pump The inclination angle remains in the warm state.
If you press the warm-up switch again during warm-up, the warm-up operation can be cancelled.
5. Power supercharger system
The power increase control flow diagram is shown in Figure 2-21.
A higher back pressure is imposed on the main safety valve to increase the safety setting pressure of the system, and the system instantly increases the power for about 10 seconds. This system only works when the mode exceeds E (engine speed is about 1700r/min).
Press the power switch, the command signal of the power switch is transmitted to the PVC, and the PVC sends the control signal to the proportional solenoid valve, commanding to open the pilot oil pressure circuit from the pilot pump to the safety valve. The pilot oil pressure acts on the spring of the safety valve through the proportional solenoid valve and increases the set pressure of the safety valve.
