1、 Disassembly and assembly of water pump

This paper takes DG type high-pressure water pump as an example. DG is a multi-stage and segmented centrifugal pump. Before disassembling it, you should be familiar with the drawings, understand the pump structure and disassembly sequence, and avoid damage to components due to mistakes. The disassembly of the pump is described in the following order.

1. Dismantling of bearing bush and measurement of bearing bush clearance

When disassembling the multistage pump, first check the bearings at both ends (usually sliding bearings), and measure the wear of bearing pads after the pump has been running for a long time (an overhaul interval). The measurement method is usually the lead wire method, as shown in the figure.

Structural drawing of bearing bush

The radial clearance of the bearing bush is generally 1 ‰ ～ 1.5 ‰ D (D is the diameter of the pump shaft). If the measured clearance exceeds the standard, the bearing bush alloy shall be poured again and scraped to be qualified. In addition, check whether the alloy layer of bearing bush has peeling, cracking and other phenomena. If the use is seriously affected, re pour the alloy. After the inspection of bearing pads, they can be disassembled in sequence, and the sequence and position shall be marked.

2. Disassembly of pump body

Remove the oil baffle after disassembling the upper bearing pads on both sides and measuring their clearance and tightening force. Then remove the packing gland, take out the packing and water seal ring, and then take down the bearing seat. For DG type water pump, it shall be disassembled from the outlet side first, and the basic sequence is as follows:

(1) First loosen the big nut and take down the threaded bolt of the pump body, and then remove the packing chamber at the outlet side and the dynamic and static balance plate components in turn. At the same time of removal, it is necessary to measure the dimensions of the adjusting sleeve, tooth shaped gasket, etc. of these components.

(2) Remove the connecting bolts of the outlet section, slowly lift out the outlet section along the axial direction, and then exit the last stage impeller, its drive key, and the distance shaft sleeve, and then remove the impellers at all levels, guide vanes at all levels, and the middle section step by step. Each impeller and distance shaft sleeve removed shall be marked to prevent wrong installation.