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Common Faults Of Gearbox Apr 11, 2020

In the long-term use, due to frequent gear shifts, the parts in the gearbox inevitably wear and deform, resulting in difficulty in gearbox gear shifting, automatic disengagement, and noise during operation, which affects the use. Therefore, in daily use, it is necessary to carry out full-load operation check on the working condition of the gearbox, observe whether the gearbox transmission is stable, and whether there are abnormal gaps and noise, and find out the reason for adjustment or repair in time.

Difficulty in gearing

When operating the gear shift gear, I feel that the gear is very laborious and cannot be smoothly entered into the gear; or there is a rattling sound when the gear is engaged, and the gear cannot be engaged when the gear is severe.

The causes are as follows:

(1) The clutch is not disconnected completely, and the power cannot be completely cut off. The specific performance is in two aspects: First, due to improper manipulation, the pedal is not stepped to the end, resulting in incomplete separation and difficulty in gear shifting. This phenomenon is common in novices. Due to inexperience, the pedal is often locked without stepping to the end, and the gear is not up to gear, and the gear is ringing. Second, it is difficult to lock the gear due to the poor clutch technical status;

(2) The teeth of the individual gears of the new car are rough, which makes it difficult to gear;

(3) The shift fork is loose and bent, the shift fork shaft is bent and corroded, and it is difficult to move. When the lock screw of the shift shaft fixing the fork is loose, it will also cause difficulty in gear shifting;

(4) The length of the reverse lever on the shift lever is improperly adjusted. When the reverse gear is engaged, the rising height of the lock plate is not enough to enter the reverse gear position smoothly.

Automatic gearshift

There are two common cases of automatic disengagement. One is to raise the accelerator pedal slightly while driving, and the gear will jump back to the neutral position; the other is to jump back to the neutral position when the uphill load increases, in this case, if you re-engage If the block is not engaged, it is easy to form a slope and a serious accident may occur.

The causes are as follows:

(1) The spring force of the shift fork is weakened or broken, making the self-locking position malfunction;

(2) The locking screw of the fork is loose, the positioning groove of the fork shaft or the steel ball of the self-locking device is worn, and the shift lever cannot be reliably positioned;

(3) The effective travel of the shift fork is small or the shift fork is bent and deformed, which results in the gear meshing not in place and easy to disengage after being stressed;

(4) The end face of the shift fork is severely worn, the gap between the end face of the shift fork and the ring groove of the sliding gear is too large, and the sliding gear is easy to shift back and forth and automatically disengage;

(5) The working surface of the gear is worn into a cone, which makes the gear meshing gap too large, which is easy to produce axial thrust, which causes the sliding gear to disengage;

(6) The spline of the gear and the shaft is worn, and the gap between the key slots is too large, so that the gear swings during transmission, and the sliding gear is easily disengaged from the meshing position;

(7) The bearing is worn, the bearing is loose, the bearing and the inner ring of the shaft slip, the bearing and the outer ring of the housing bore slip, and the axial gap is too large, which causes the gear shaft to tilt and the gear shaft to shift, resulting in gear After force, it will automatically disengage.

Abnormal sound of gearbox

There are two conditions for the abnormal sound of the gearbox: one is the abnormal noise when it is in the neutral position; the other is the abnormal noise when it is shifted while driving.

The causes are as follows:

(1) Insufficient gear oil or poor gear oil quality;

(2) The gear tooth surface is severely worn, making the meshing gap too large;

(3) Fatigue spalling or chipping of gear teeth;

(4) The intermediate shaft and the second shaft are excessively worn, or the spline shaft and the spline in the gear are seriously worn, and the gap is too large; the shaft is bent or the lock on the shaft is loose;

(5) The bearing is loose or the cage is damaged;

(6) The non-working parts of the fork contact and rub;

(7) Instead of replacing the gears in pairs during repair, replace the new gears individually.