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Hydraulic gear pump failure and maintenance

Author : Xiong Date : 8/25/2012 6:46:50 PM
Hydraulic gear pump failure and maintenance

Execute component in the work speed can not reach the specified value, the main cause is the hydraulic system supply pressure oil shortage. Pressure oil shortage are caused by many factors, execute component hydraulic cylinder, hydraulic motor own leakage, a hydraulic system joint and pipeline leakage, controlled by hydraulic system element leakage, etc. In addition to the above reason outside, gear pump of the internal leakage is first selection spent object.

Gear pump radial leakage treatment

Gear pump intermediate pump body and gear tooth surface (circular, arc) wear or shave.
Reasons. Two gear backlash partial small, easy to cause the gear form surface bite, shave. Hydraulic cleanliness is poorer, easy to cause the tooth surface is not normal wear and tear.

Repair methods. Western Europe the tooth surface, cleaning system pipeline, control components, fuel tank, and replace filter valve core; Eat form surface wear, usable dye check, oil ShiXiu grinding injured tooth mesh surface, assembly will two gear meshing surface exchange azimuth, make originally injured meshing surface transposition is a mesh surface, and this can be normal use.
Pump of trapped oil phenomenon

Whether hydraulic pump or hydraulic motor, it is with the aid of volume change and work, in the work process volume must be sealed, and continually turned from small to big or by bigger or smaller, the change process separately and brook oil cavity and discharge cavity are interlinked, if the volume of sealing in a certain instantaneous inside is different brook oil cavity are interlinked, also different discharge cavity are interlinked, and sealed volume size but in change, this kind of phenomenon is called trapped oil phenomenon.
Eliminate method, before and after the end cover on milling unloading trough, unloading tank size a shall ensure that trapped oil space in the minimum position before and discharge cavity connected, the minimum location and brook oil cavity connected. So less than can eliminate trapped oil phenomenon, but also can make the trapped oil into a pump in the small pump.


Gear pump internal leakage possible position

Two gear meshing line place. General hydraulic pump processing precision is higher, and gear each other between the bite force also is bigger, so through the leakage quantity is less, occupy the whole pump leakage around 5%.
Radial clearance. Refers to the gear top and pump body between the cylinder clearance, the leakage from here, occupy the whole pump leakage amount of 15% ~ 20%.

Axial clearance. Refers to the gear face and bearing race or end cover plane between the clearance, due to axial clearance area is larger, oil seal length is short, therefore, through the oil leakage is the most serious, the leakage of pump total leakage about 75% ~ 80%.
Improve pump volume efficiency of the method

Volumetric efficiency is the effective output flow and light output flow ratio, the improvement of the machining precision and material stiffness and using automatic compensation structure method, can reduce fit clearance, improve volumetric efficiency.
To improve the machining precision of parts, selecting reasonable axial clearance. Big flow pump axial clearance generally take 0.03 ~ 0.06 mm; Small flow pump axial clearance generally take 0.02 ~ 0.04 mm. Radial clearance can be increased to 0.13 ~ 0.16 mm.
Improve the pump body stiffness and reduce the end cover by liquid pressure deformation, to keep the axial clearance under different pressure in basically unchanged.

The axial clearance self-compensation structure, high pressure pump axial clearance can along with the work pressure increases and automatic reduce. So as to eliminate the gap, greatly reduce the internal leakage. Hydraulic pump working pressure can be increased to 15 mpa, that is shaft sleeve and gear face be wear, also won't produce big clearance, so this kind of pump has a long service life.

Gear pump axial leakage treatment

Gear pump, before and after the end cover face and gear two end wear or shave.
Causes. Pump intermediate pump body thickness and two gear tooth clearance after partial small; Hydraulic oil cleanness is poorer, easy to cause the abnormal wear and shave.

Repair methods. The gear pump, before and after the end cover injured face grinding or flat grinding after grinding; Two gear injury face grinding or flat grinding after grinding. After grinding surface roughness to Ra0.8 um less than, surface flatness of 0.005 mm within; Intermediate pump body thickness should make two gear thick size distribution grinding clearance in 0.02 ~ 0.03 mm range. Keep hydraulic oil cleaning, cleaning system pipeline, control components, fuel tank. Replace filter valve core. In the repackaging repair gear pump that should pay attention to clean, civilized assembly.


Gear pump noise increases the reasons and treatment methods

Gear pump noise increases causes a gear pump of the transmission shaft and motor shaft not coaxial, axis offset, the axis imbalance, two axis misalignment, pump gear precision low or tooth surface wear or nap, skeleton oil seal damage, brook tubing or filter plugging, oil tank are air, etc.

Elimination method. Check the skeleton oil seal and pump body fit situation, if the former plate with hole unqualified should be replaced the former end cover, or replace skeleton oil seal, Clean the hydraulic oil change, clear drainage hole of the impurity; According to the right direction repackaging pump body; Reassemble gland, the accurate control of gland pressure depth, both must avoid jams oil return channel, but also to prevent to produce leakage phenomenon; According to the gear pump axial and radial leakage repair gear pump parts processing methods.

Repair methods: reinstall the hydraulic pump, motor. Coaxial degree adjustment in the reasonable scope; Replace skeleton oil seal, Clean brook line, filter, Replace liquid cylinder.
Pump skeleton oil seal or gland is oil rushed out of the reasons and treatment methods
Reasons. Skeleton oil seal and pump body before end cover fit too loose; Oil not clean, the drainage hole was impurities clogging; Pump body direction reverse loading, use oil mouth and unloading trough on produce pressure; Before and after gland jam the front end cover of the oil return channel, the oil return hindered; Pump wear serious, excessive leakage.

The above: Gear pump principle and maintenance of common sense