The function of the lock ring is to accurately stay in the original position when the actuator is not working, and will not change its position due to leakage or external factors. The simplest way to lock the hydraulic cylinder is to use the M-shaped or 0-shaped neutral function of the three-position reversing valve to seal the two cavities of the hydraulic cylinder. However, due to the leakage of the slide valve, it cannot be kept in a certain position for a long time, and the locking accuracy is not high. The most commonly used method is to use hydraulic control one-way valve as locking element.

Figure 7.30 shows the locking circuit of the hydraulic leg of the crane. Two hydraulically controlled one-way valves (two-way hydraulic locks) are used in the circuit. The hydraulic control one-way valve has good sealing performance and the oil cylinder can be locked for a long time. It is best to use H-shaped or Y-shaped reversing valve with neutral function for hydraulic lock. Once the reversing valve returns to the neutral position, the control pressure of the hydraulic control one-way valve will be unloaded immediately, so the hydraulic control one-way valve will be closed immediately. Generally, the two-way hydraulic lock is directly installed on the oil cylinder, and there is no hose connection in the middle, so there will be no accident due to hose bursting, which has the function of safety protection.

When the actuator is a hydraulic motor, it should stop rotating after cutting off its oil inlet and oil outlet. However, because the motor also has an oil drain directly connected to the oil tank, when the motor becomes a pump under the action of gravity load torque, the oil at its outlet will flow through the oil drain.

Go back to the oil tank and make the motor slip. Therefore, when the oil inlet and outlet of the motor are cut off, it is necessary to ensure the reliable stop of the motor through the hydraulic brake, as shown in Figure 7.438+0:

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