Several key points of gear oil pump maintenance

With the increase of service time, the gear oil pump will have faults such as insufficient pump oil or even no pump oil, mainly due to excessive wear of relevant parts. The wear parts of gear pump mainly include driving shaft and bushing, center hole and shaft pin of driven gear, inner cavity of pump shell and gear, gear end face and pump cover, etc. After the lubricating oil pump is worn, if its main technical indexes fail to meet the requirements, it shall be disassembled, the worn parts and degree shall be found out, and corresponding measures shall be taken to repair it.

1、 Repair of lubricating oil pump shell crack repair of shell crack: the shell crack can be repaired by casting 508 nickel brazing electrode. The weld must be tight and free of air holes, and the flatness error of the joint surface with the pump cover shall not be greater than 0.05mm

2、 Repair of worn driving shaft and bushing

After the driving shaft and bushing of gear pump are worn, the matching clearance will increase, which will affect the amount of pump oil. In this case, the normal fit clearance can be restored by repairing the driving shaft or bushing. If the driving shaft is slightly worn, just press out the old bushing and replace it with a bushing of standard size, and the fit clearance can be restored to the allowable range. If the driving shaft and bushing are seriously worn and the fit clearance seriously exceeds the standard, not only the bushing shall be replaced, but also the diameter of the driving shaft shall be increased by chromium plating or vibration surfacing, and then ground to the standard size to restore the fit requirements with the bushing.

Repair of wear of driving shaft bushing hole and driven shaft hole: after the driving shaft bushing hole is worn, the wear trace can be eliminated by reaming, and then the bushing increased to the corresponding size can be used. The wear trace of the driven shaft hole shall also be eliminated by reaming, and then the driven shaft shall be prepared according to the actual size of the reamed hole

Repair of the inner cavity of the pump casing: after the inner cavity of the pump casing is worn, the inner cavity inlay method is generally adopted for repair, that is, after the inner cavity is lined with large, it is inlaid with cast iron or steel bushing. After the sleeve is inserted, the inner cavity shall be lined to the required size, and the bushing protruding from the end face shall be ground off to make it flush with the joint surface of the pump housing

Repair of valve seat: there are two kinds of pressure limiting valves: ball valve and plunger valve. After the ball valve seat is worn, put a steel ball on the valve seat, and then gently tap the steel ball with a metal rod until the ball valve is close to the valve seat. If the valve seat is seriously worn, ream it first to remove the wear marks, and then use the above method to make it close. After the plunger valve seat is worn, add a little valve sand for grinding until it is tight

3、 Overturning use of gears

The gear wear of gear pump is mainly at the tooth thickness, while the wear of gear end face and tooth top is relatively light. The gear is worn on one side at the tooth thickness, so the gear can be turned over 180 degrees. When the gear end face is worn, the end face can be ground flat and the joint surface of the lubricating oil pump housing can be ground at the same time to ensure that the clearance between the gear oil pump end face and the pump cover is within the standard range

4、 Repair of pump cover

Repair of working plane: if the wear of the working plane of the pump cover is small, the wear trace can be eliminated by manual grinding, that is, put a little valve sand on the platform or thick glass plate, and then put the pump cover on it for grinding until the wear trace is eliminated and the working surface is flat. When the wear depth of the working plane of the pump cover exceeds 0.1mm, the method of turning before grinding shall be adopted for repair

Repair of driving shaft bushing hole: the repair method for wear of driving shaft bushing hole on pump cover is the same as that of housing driving shaft bushing hole.