Is There A Difference Between An Unloading Valve And A Relief Valve?

Is There A Difference Between An Unloading Valve And A Relief Valve?

different in nature

1. Relief valve: a hydraulic pressure control valve, which mainly plays the role of constant pressure overflow, constant pressure, system unloading and hydraulic equipment safety protection.

2. Unloading valve: Under certain conditions, the valve can unload the hydraulic pump.

The effect is different

1. Overflow valve: In the quantitative pump throttling adjustment system, the quantitative pump provides a constant flow. As system pressure increases, flow demand decreases. At this time, the safety valve is opened to return the excess flow to the oil tank to ensure that the inlet pressure of the safety valve, that is, the outlet pressure of the pump is constant (the valve port often opens with pressure fluctuations).

2. Unloading valve: Automatically control pump unloading or loading. In view of the function of the unloading safety valve, there is a certain difference between the unloading pressure and the loading pressure. If the pressure difference is too small, the pump will be unloaded and loaded too frequently; if the pressure difference is too large, the pressure of the system will change too much.

Working principle of unloading valve:

1. System composition:

Under different working conditions, the basic composition of the control system is different.

2. Working principle of hydraulic system:

The control system of the working device is provided by two oil pumps. The main pump is P7600-F100. Used to control the movement of the boom and bucket cylinders. The pilot pump is P124-G16. It is used to control the proportional pilot valve, and then control the displacement of the main reversing spool, thereby controlling the working speed of the boom and bucket cylinder. The oil from the pilot pump enters the brake valve first. In addition to ensuring brake oil, it also provides a source of control oil to the pilot system.

The oil is reduced to the control pressure required by the pilot control system through the pressure-reducing valve, and then enters the control oil circuit to control the operation of the working device.

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