The hydraulic gear pump is an important part of the hydraulic system, but when we use the hydraulic gear pump, there will inevitably be some faults. Today, I will introduce how to solve these faults.
1. The pump does not produce oil
If it is found that the gear pump does not receive oil during the debugging of the main engine, first check whether the rotation direction of the gear pump is correct. The gear pump is divided into left and right rotations. If the rotation direction is wrong, the pressure oil formed by the volume difference generated by the meshing of the internal gears will cause the oil seal to be washed out and oil leakage. Secondly, check whether the oil filter at the oil inlet end of the gear pump is blocked, which will make it difficult to absorb oil or not be able to absorb oil, and cause the phenomenon that the oil suction hose is sucked flat.
2. The oil seal is flushed out
(1) The rotation direction of the gear pump is incorrect. When the rotation of the pump is incorrect, the high-pressure oil will directly pass to the oil seal. Because the general low-pressure skeleton oil seal can only bear the pressure of 0.5MPa at most, the oil seal will be flushed out.
(2) The gear pump bearing is subjected to axial force. The generation of axial force is often related to the over-tight fit between the shaft extension end of the gear pump and the shaft sleeve, that is, the pump shaft is subjected to a backward axial force when the pump is smashed with a hammer or hard-drawn through the installation screw during installation. As the shaft rotates, this rearward axial force will force increased wear on the pump. Since the inside of the gear pump is sealed by the end face of the gear and the end face of the shaft sleeve, when the end face of the axial seal is seriously worn, a certain gap will be generated in the axial seal inside the pump, resulting in the communication between the high and low-pressure oil chambers and the oil seal flushing out. . This situation occurs frequently in the dump truck industry, mainly due to the irregular size of the coupling sleeve on the main engine.
(3) The gear pump is subjected to excessive radial force. If the coaxiality of the gear pump is not good, the radial force on the pump will exceed the bearing limit of the oil seal, which will cause the oil seal to leak. At the same time, it will also cause damage to the floating bearing inside the pump.
(4) The gear pump is sucked or half sucked for a long time, which will increase the wear of the end face of the gear and the shaft sleeve. Since the gear pump is sealed by the end face of the gear and the end face of the shaft sleeve, when the end face of the axial seal is seriously worn At this time, the axial seal inside the pump will have a certain gap, which will lead to the communication between the high and low-pressure oil chambers and the oil seal will be flushed out.
3. Can't build or not have enough pressure
This phenomenon is mostly related to the cleanliness of the hydraulic oil. If the oil is not selected correctly or the cleanliness of the oil in use does not meet the standard requirements, the internal wear of the pump will be accelerated, resulting in leakage. Therefore, mineral hydraulic oil with additives should be selected, which can prevent the oil from oxidizing and generating air bubbles. The viscosity standard of the oil is (16～80)×10-6m2/s The filtration precision is: the input oil circuit is less than 60цm. By observing the shaft sleeve and side plate of the faulty gear pump, it is found that if the cleanliness of all oils is poor, obvious groove marks will be formed on the surface of the friction pair, while the normally worn gear pump sealing surface will only produce uniform surface marks.
4. Traffic is not up to standard
(1) The oil inlet filter element is too dirty and the oil absorption is insufficient.
(2) The installation height of the pump is higher than the self-priming height of the pump.
(3) The oil suction pipe of the gear pump is too thin, resulting in a large oil suction resistance. Generally, the maximum oil absorption flow rate is 0.5 to 1.5 m/s.
(4) Air leakage from the oil suction port joint causes insufficient oil suction of the oil pump. By observing whether there are air bubbles in the fuel tank, you can determine whether the system is leaking.
5. Gear pump burst
The pressure resistance of the aluminum alloy gear pump is 38-45MPa. Under the premise of no manufacturing defects, the burst of the gear pump must be caused by the instantaneous high pressure.
(1) The oil outlet pipeline is blocked by foreign objects, causing the pressure to rise infinitely.
(2) The pressure adjustment of the safety valve is too high, or the opening and closing characteristics of the safety valve are poor, and the response is delayed so that the gear pump cannot be protected.
(3) If the system uses a multi-way reversing valve to control the direction, some of the multi-way valves may have a negative opening, which will cause the gear pump to be suffocated due to the dead point boost.
6. Fever
(1) The system is overloaded, which is mainly manifested in excessive pressure or high speed.
(2) The cleanliness of the oil is poor, the internal wear is aggravated, the volumetric efficiency is reduced, and the oil leaks and throttles from the internal gap to generate heat.
(3) The oil outlet pipe is too thin and the oil flow rate is too high. Generally, the oil outlet flow rate is 3-8m/s.

For more information, please contact Hydraulic Pump Company!