Piston pump is an important equipment in hydraulic systems. By reciprocating the plunger in the cylinder, the volume of the sealed working chamber changes, thereby achieving the functions of oil suction and pressure.

 

Maintenance method for piston pump

 

1. Check for any damage or rust on the plunger pump, and replace it if necessary.

 

2. Check whether the pressure reducing ring of the oil outlet valve is worn, has steps or marks, and replace it if necessary.

 

3. Check the sealing of the plunger pair. Hold the plunger sleeve with your hand and block the oil inlet on the top and side of the plunger with two fingers.

 

4. Check the coordination of the oil outlet valve pair.

 

5. Check the fit of the plunger pair. Insert the plunger end into the plunger sleeve and tilt it about 60 °. If the plunger can slowly slide down under its own action, it is considered a good fit.

Abnormal output pressure phenomenon of piston pump

 

The output pressure of the pump is determined by the load and is approximately proportional to the input torque. There are two types of faults for abnormal output pressure.

 

(1) Output pressure too high

 

If the circuit load continues to rise and the pump pressure also continues to rise, it is considered normal. If the load is constant and the pressure of the pump exceeds the required pressure value for the load, hydraulic components other than the pump, such as directional valves, pressure valves, transmission devices, and return oil pipelines, should be checked. If the pressure is too high, adjust the overflow valve.

 

(2) Output pressure too low

 

When the pump body is in a self-priming state, if there is a leak in the inlet pipe, or if there is a significant leak in the hydraulic cylinder, one-way valve, directional valve, etc. in the system, it will cause the pressure to rise. This requires finding the leakage point, tightening, replacing the seal, and then applying pressure. When a malfunction occurs or the pressure is adjusted to a low level, and the system pressure is too high, the pressure should be readjusted or the overflow valve should be repaired. If there is a deviation between the cylinder body and the distribution plate of the hydraulic pump, resulting in a large amount of leakage, and in severe cases, it may cause the cylinder body to break, the mating surface should be re polished or the hydraulic pump should be replaced.

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