Created on:2022-02-15 13:27

Cause analysis and repair of NJM-10 hydraulic motor front cover plate damage

Cause analysis and repair of NJM-10 hydraulic motor front cover plate damage

1. Introduction

NJM-10 is widely used in coal mine production. It has the characteristics of large transmission torque, good low-speed stability and high starting efficiency. It belongs to the inner curve hydraulic motor and is the executive element of the hydraulic system of the traction part of DY-150 shearer.

In general, the failure of internal curve hydraulic motor will be caused when the plunger, roller, oil distributor and seal are improperly installed or worn. During the maintenance of NJM-10 hydraulic motor, it is found that the front cover plate of hydraulic motor is worn to varying degrees, and a considerable proportion of hydraulic motors need to replace the front cover plate. Therefore, it is necessary to analyze the causes of wear.

2. Cause analysis of wear of front cover plate

(1) Wear of anchor chain to front cover plate. During the traction process of shearer, the front cover plate of hydraulic motor is worn due to chain clamping. The chain jam is caused by the incorrect chain tightening mode, that is, there is a problem with the tensioning device at both ends of the traction chain (at present, most of them use the hydraulic tensioning device), which causes the sprocket to fail to spit out the chain in time, resulting in chain jam.

(2) Wear of sprocket to front cover plate. Due to the impact load on the sprocket in the working process during the traction of the shearer. When the perpendicularity between the sprocket axis and the outer plane of the front cover plate is out of tolerance due to improper bearing installation, bearing wear, spline shaft wear and other factors, the contact between the sprocket and the front cover plate will be caused under the action of pulsating load, resulting in wear.

(3) The wear of gangue and coal on the front cover plate. As the sprocket is horizontally placed between the casing and bracket of the traction part, gangue and coal are easy to enter between the sprocket and the cover plate of the hydraulic motor, resulting in serious wear.

Through the above analysis, it can be seen that the wear of the front cover plate of the hydraulic motor is inevitable.

3. Repair of front cover plate

As shown in Figure t (a), it is the structural diagram of the front cover plate. On the structure of the front cover plate, if the area m is seriously worn, the sealing ring can not be installed, and the dust-proof effect is invalid. When this failure occurs, the simplest way is to re process a new front cover plate and replace it, but the maintenance cost is very high and the processing cycle is also long.

In order to reduce the maintenance cost and shorten the maintenance cycle, in the actual maintenance, make rational use of the damaged front cover plate, turn off the damaged part, and then fill it up according to the original size. Its structure is shown in Figure t (b). The two parts 1 and 2 can be connected with four ml6 screws, and their matching is clearance matching. When connecting, under the condition of ensuring the original size, the following technical treatment needs to be done. When screwing in the screws, Apply a layer of anaerobic adhesive on the screw; 1. 2. A sealing gasket shall be added to the joint surface of the two parts.

The wear fault of NJM-10 hydraulic motor front cover plate has been repaired by the above methods, and the effect is very good in practical application. This repair method has the advantages of simple process, low maintenance cost and short cycle, and has certain practical significance.

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