Created on:2022-02-15 13:27

Cause analysis and Countermeasures of oil leakage of hydrostatic motor oil seal of DF4 locomotive

Cause analysis and Countermeasures of oil leakage of hydrostatic motor oil seal of DF4 locomotive

1. Introduction

On DF4 locomotive, the hydrostatic motor is used to drive the cooling fan to cool the cooling water system to maintain the normal oil and water temperature, so as to ensure the normal operation of the diesel engine. In the process of practical application, oil leakage of hydrostatic motor oil seal often occurs, which not only wastes oil and pollutes the environment, but also may make the cooling fan work abnormally when the oil leakage is serious, resulting in machine damage and temporary repair, which seriously affects the transportation safety of the railway.

The spindle of hydrostatic motor adopts skeleton oil seal axial seal structure, and the oil seal model is sg65 × ninety × 12. Its assembly with the main shaft and oil seal end cap is shown in Figure Q.

2. Failure analysis

51 DF4 locomotives in a locomotive depot are investigated. The main task of the locomotive is passenger and freight traction. Due to the large fluctuation of line slope, many tunnels and the long working time of hydrostatic motor under full speed operation, there are many oil leakage faults of hydrostatic motor oil seal. In two years, there were 22 oil leakage faults of hydrostatic motor oil seal. The main fault parts are as follows:; Spindle wear 12 pieces; 9 cracked oil seals; Other l pieces. Among them, the most harmful is the oil seal crack, because there is a large amount of oil leakage after the failure here, and the possibility of mechanical failure is the greatest; The second is spindle wear.

3. Failure cause analysis

(1) The oil seal is damaged due to improper assembly.

In order to make the seal between the oil seal and the oil seal cover work well, the installation interference between the oil seal and the oil seal cover is 0.1 ~ 0.2mm. Therefore, the oil seal needs a large force in the process of installing the oil seal cover. During actual assembly, due to the lack of suitable special press fitting tools, workers often knock the oil seal with the wooden handle of screwdriver or other items, or simply press the oil seal with sharp objects to make it enter the oil end cover. In this way, problems such as deformation of oil seal iron skeleton and slight crack of oil seal rubber may occur after assembly. Oil leakage of oil seal may be caused after loading and application, Even the oil seal is broken.

(2) The spindle of hydrostatic motor is worn.

The maximum working oil pressure of the hydrostatic motor is more than 14MPa. In order to make the oil seal work well, the inner diameter of the oil seal belt is about 3mm smaller than the outer diameter of the main shaft, and it is clamped on the main shaft with a spring. There is a certain friction when the main shaft rotates. In addition, for the cooling fan installed on the main shaft, there is no dynamic balance test device in each locomotive depot. When the fan works at full speed, it will produce a certain deflection force on the main shaft of the hydraulic motor, so as to increase the above friction. Therefore, after long-term use, the main shaft generally has a circumferential groove at the sealing belt, which affects the sealing effect of the oil seal. When the groove reaches a certain depth, it may cause oil leakage of the oil seal.

4. Countermeasures

(1) Use thickened oil seal end cap. For the oil seal leakage fault caused by the wear of the main shaft, the traditional treatment method is generally to lift the leaking hydrostatic motor from the vehicle, coat or chrome the hydrostatic motor main shaft, and then put it into use after restoring the original size. This method has many inconveniences in the field practice. First, the hydrostatic motor on the vehicle is only oil leakage. If the hydrostatic motor is lifted down and completely disassembled, it will inevitably cause a waste of human and material resources; The second is to repair the circumferential wear of the hydrostatic motor main journal by chromium plating, which has a large workload and high cost.

Through observation and analysis, we have made a thickened oil seal end cap and replaced it with the original oil seal end cap, which can adjust the position of the skeleton oil seal on the main shaft of the hydrostatic motor, move the installation position of the oil seal upward, avoid the wear part of the main shaft of the hydrostatic motor, and make the main shaft reused. The thickened oil seal end cap is as shown in Figure R. just increase the size of parts A and B in the oil seal end cap with drawing No. dlt220-00-o1-1 by 3mm respectively.

R.jpg

(2) Use the special press fitting tool for oil seal. For the failure of oil seal rupture, a special tool can be made, as shown in Figure s. When assembling the oil seal, increase the bearing area when the oil seal is pressed down to prevent damage to the oil seal rubber and the built-in framework.

By taking the above measures, the oil leakage fault of hydrostatic motor oil seal in the locomotive depot has been significantly reduced, the machine damage and temporary repair caused by it have been effectively controlled, the maintenance cost of locomotive has been reduced and the driving safety has been ensured.

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