PC200-6 PC300-6 main gun relief valve 708-2L-04312

The relief valve for hydraulic excavators has four main functions:

1, in the quantitative pump (gear pump) hydraulic system, used to overflow excess oil flow back to the tank to maintain the hydraulic system pressure constant (approximately constant).

2, in the variable pump hydraulic system, only when the pressure exceeds a preset pressure value, the overflow is opened, so that the system pressure is no longer raised, and the safety protection role is often called the relief valve.

3, in the system, used to protect the actuator (such as the cylinder) or structural parts under the action of a strong external force is not damaged, in this case, the relief valve, we call the overload valve.

4, as a pressure limiting valve, the rotary mechanism for cushioning, limiting pressure.

The working principle of the relief valve

1. Pump pressure PP rises

2, more than 21.6MP

3, the pump pressure to push the lifting head to overcome the spring force to push upward

4. The small hole in the plunger (only 0.5) begins to have oil flow

5. The plunger is pushed upward due to the pressure difference between the front and back (the bottom is large and the top is smaller)

6, pressure oil back to the tank

7, pump pressure drop until 21.6