Common faults and causes of gear pumps

1Gear oil pump does not discharge oil

First, check if the rotation direction of the gear pump is correct. Secondly, check if the oil filter at the inlet end of the gear pump is blocked.

2. The oil seal is punched out

1) The rotation direction of the gear pump is incorrect.

2) The gear pump shaft is subjected to axial force.

3) The gear pump is subjected to excessive radial force.

Rotate the coupling by hand, feeling light and even force.

Check the rotation direction of the pump, which should match the direction indicated on the label on the pump body.

Check if the hydraulic system has a unloading circuit to prevent full load starting and stopping.

Check if the protective valve in the system is at the set allowable pressure.

Fill the oil outlet with oil to prevent component damage due to dry friction during pump start-up.

Run the pump under no load for no less than 2 minutes and check if the pump's operating sound is normal and the direction of the liquid flow is correct.

Adjust the pressure of the relief valve to below 1. OMPa and rotate it for 5-10 minutes to check if the system's operation, external leakage, noise, temperature rise, etc. are normal.

Adjust the pressure of the relief valve to the protective pressure of the hydraulic system for operation.

Unable to establish pressure or insufficient pressure

It is often related to the cleanliness of hydraulic oil. If the oil selection is incorrect or the cleanliness of the oil does not meet the standard requirements, it will accelerate the internal wear of the gear pump, leading to internal leakage. Mineral hydraulic oil containing additives should be selected to prevent oil oxidation and the formation of bubbles. The filtering accuracy is: the input oil circuit is less than 60 μ m. The return oil circuit is 10-25 μ M.

4. The traffic does not meet the standard

1) The oil inlet filter is too dirty and lacks oil suction.

2) The installation height of the pump is higher than the self suction height of the pump.

3) The oil suction pipe of the gear pump is too thin, causing high oil suction resistance. The generally larger oil suction flow rate is 0.5-1.5 m/s.

4) The leakage of the oil suction joint caused insufficient oil suction by the pump. By observing whether there are bubbles in the fuel tank, it can be determined whether the system is leaking.

5-wheel pump exploded

The pressure resistance of the aluminum alloy material gear pump is 38-45 MPa. On the premise of no manufacturing defects, the explosion of the gear oil pump is definitely caused by instantaneous high pressure.

1) The oil pipeline is blocked by foreign objects, causing pressure to rise.

2) The pressure adjustment of the protective valve is too high, or the opening and closing characteristics of the protective valve are poor, resulting in delayed response and the gear pump cannot be protected.

3) If the system uses a multi way directional valve to control the direction, some multi way valves may have negative openings, which may cause the gear pump to be damaged due to dead center pressure increase.

6 Heat generation

1) System overload, mainly manifested in high pressure or speed.

2) The cleanliness of the oil is poor, and internal wear intensifies, resulting in a decrease in volumetric efficiency. The oil leaks from the internal gap and generates heat due to throttling.

3) The oil outlet pipe is too thin, and the oil flow rate is too high. Generally, the oil flow rate is 3-8 m/s.

7. Severe noise and pressure fluctuations

1) The clogged dirt in the oil filter cannot filter the oil; Or the oil level is insufficient, the suction position is too high, and the suction pipe is exposed to the oil surface.

2) There are no paper pads on both sides of the pump body and pump cover, causing a hard object collision. The pump body and pump cover are not vertically sealed, and air is sucked in during rotation.

3) The driving shaft of the pump is not concentric with the motor coupling, resulting in twisted friction; Or the gear meshing accuracy of the gear pump is insufficient