How to Repair Gear Pump

Figure 1: Gear pump.

In the previous article, we introduced a lot about the gear pump, so how to install the gear pump? Let's talk about it today.

1. Repair Steps

1.1 Disassembly

Before disassembly, please make full preparations and be familiar with the equipment structure, process flow and operation status; Be careful during disassembly to avoid damaging equipment parts.

1.2 Recheck Data

Comprehensively check the fitting clearance of all parts of the gear pump,

1.3 Inspection

Conduct a detailed inspection of the removed parts and components, then conduct a coloring inspection of the gear, and no cracks are allowed; The taper of the journal must be qualified, and the surface must be free of scratches. The maximum allowable roughness Ra is 1.6μm；The end cover, bracket and pump body should be free of obvious defects.

1.4 Repair or Replace

Figure 2: Replace the parts exceeding the standard.

The parts exceeding the standard should be replaced. The parts and components to be repaired should meet the standards.

1.5 Assembly and Adjustment

Adjust the thickness of the sealing gasket between the bracket and the pump body; When tightening the bolts of the end cover, the force shall be symmetrical and uniform, and the rotor shall be rotated while tightening. When the rotor cannot rotate, the bolts shall be loosened and re tightened; When adding filler or installing oil seal, it is necessary to rotate the rotor while tightening, and it cannot be fixed too tightly.

1.6 Commissioning

The water pressure shall be 1.5 times of the working pressure and shall be kept for 5min without leakage. During the test run, there should be no leakage, normal operation sound, no abnormal vibration, and the outlet pressure should meet the requirements.

2. How to Maintain the Gear Pump

Figure 3: Inner structure of the gear pump.

When we use the gear pump, we cannot avoid the wear of the gear pump, so,many problems will occur. We should learn the most common maintenance technology for the gear pump. Then when the fault occurs, we can make an accurate judgment. Then, I want to tell you something about the maintenance technology:

2.1 Maintenance of the Working Plane

If the wear of the working plane of the pump cover is relatively small, you can remove the wear marks by grinding yourself, that is, put a little valve sand on the platform or thick glass plate. Then put the pump cover on it for grinding until the wear marks are removed and the working surface is flat. If the wear depth of the working plane of the pump cover exceeds 0.1 mm, it should be repaired by turning first and then grinding.

2.2 Maintenance of the Driving Shaft Bushing Hole

The maintenance method for the wear of the driving shaft bushing hole on the pump cover is the same as that of the housing.

2.3 Repair of the Inner Cavity of the Pump Casing

The wear of the inner cavity of the pump casing can be repaired by the inner cavity inlay method, that is, after the inner cavity is lined up, it is inlaid with cast iron or steel bushing. After inserting the sleeve, 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.

2.4 Maintenance of Valve Seat

There are two kinds of pressure limiting valves: ball valve and plunger valve. After the ball valve seat is worn, a steel ball can be placed on the valve seat, and then gently tap the steel ball with a metal rod until the ball valve is tightly closed with the valve seat. If the valve seat is seriously worn, ream it to remove the wear marks, and then use the above method to make it close. After the plunger valve seat is worn, a little valve sand can be put into it for grinding until it is close.

3. Final Thoughts

The above is about the maintenance of some of the most basic parts of the gear pump. We may encounter different problems in other aspects in the process of application. So, we should seriously discuss these different problems and find out the reasons for the problems.

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