The gear pump works by twisting and rotating the two gears, and the requirements on the medium are not high. The general pressure is below 6 MPa and the flow rate is large. The gear oil pump is equipped with a pair of slewing gears in the pump body, one active and one passive, and the two working parts in the pump are divided into two separate parts by the mutual engagement of the two gears. A is the suction chamber and B is the discharge chamber. When the gear oil pump is in operation, the driving gear drives the driven gear to rotate. When the gear is engaged to disengage, a partial vacuum is formed on the suction side (A), and the liquid is sucked. The inhaled liquid fills the respective valleys of the gear and is brought to the discharge side (B). When the gear enters the mesh, the liquid is squeezed out to form a high-pressure liquid and exit the pump through the pump discharge port.
When the gear oil pump is in use, there is often a shortage of oil supply or no oil pressure. We do the following analysis of this fault to facilitate fault inspection and maintenance of the gear pump.
phenomenon:
(1) The working device is lifted slowly, shaking or lifting when lifting;
(2) There are air bubbles in the fuel tank or oil pipe;
(3) The hydraulic system emits a "beep, bang" sound when lifting;
(4) The working device can be lifted when the tractor is started. After the oil temperature rises for a period of time, the lifting is slow or cannot be improved;
(5) It can be lifted under light load and cannot be lifted under heavy load.
Gear oil pump failure reason:
(1) The hydraulic oil tank is too low;
(2) The hydraulic oil is not used according to the season;
(3) The oil inlet pipe is seriously blocked by dirt;
(4) The oil pump drive gear oil seal is damaged and the air enters the hydraulic system;
(5) The oil-inlet inlet and outlet joints or the bent joint “O”-shaped seal ring are damaged. The fastening bolts of the bent joint or the inlet and outlet oil pipes are not tightened, and the air enters the hydraulic system;
(6) The inner leakage of the oil pump and the sealing ring aging;
(7) The end face of the oil pump or the end faces of the main and driven gear bushings are worn or scratched, and the unevenness of the end faces of the two bushings is excessive;
(8) Internal leakage caused by incorrect assembly of internal parts of the oil pump;
(9) "Left-spin" installed "right-handed" oil pump, causing damage to the skeleton oil seal;
(10) The hydraulic oil is dirty.
Gear oil pump elimination method:
(1) Add or replace the oil that meets the required grade according to the season to the specified oil level. Remove the foreign matter in the oil pipe and tighten the bolt or nut at the joint;
(2) Replace the aging or damaged skeleton oil seal or "O" sealant ring;
(3) Replace the worn gear oil pump or oil pump bushing, and smooth the end face on the flat plate when the wear is slight. The unevenness of the unevenness is 0.03mm; the end face of the upper bushing is lower than the upper plane of the pump body (normal value is less than 2.5~2.6mm). If it is out of tolerance, it should be compensated by adding 0.1~0.2mm copper piece to the lower bushing. Should be placed on the rear bushing;
(4) The unloading plate and the sealing ring must be installed in the oil inlet cavity, and the two bushings can be balanced. The relief gasket should have a preload of 0.5mm;
(5) The guiding wire elastic force should be able to twist the upper and lower bushings at a slight angle to the rotating direction of the driven gear at the same time, so that the processing planes of the two bushings of the main and driven gears are closely fitted;
(6) The unloading groove on the sleeve must be installed on the side of the low pressure chamber, and the oil pump can eliminate the harmful dead volume when the gear meshes;
(7) Before pressing the self-tightening oil seal, it should be coated with a layer of lubricating oil on the surface, and also pay attention to the oil-resistant edge toward the front cover, which cannot be reversed;
(8) The “right-handed” pump cannot be installed on the “left-handed” machine, otherwise it will damage the skeleton oil seal;
(9) Before loading the pump cover, pour a small amount of oil into the pump casing and turn the meshing gear by hand;
(10) Before installing the oil pump cover without tightening the bolt, check whether the gap between the pump cover and the pump body is between 0.3 and 0.6 mm. If the clearance is too small, replace the large seal ring and the pressure relief member. After the hydraulic oil pump is installed, it should be flexible and free from sticking.