Analysis and diagnosis of abnormal noise of rear axle of tractor chassis

(1) The main causes of rear axle abnormal noise are as follows:

The bearing is loose and damaged; the gear is poorly meshed and damaged; the reducer housing is deformed.

(2) Abnormal sound diagnosis.

① There is abnormal noise during driving. The abnormal noise weakens or disappears when sliding out of gear. This fault is generally caused by too large meshing clearance between the bevel and cylindrical driving and driven gears, planetary gears and half shaft gears, loose fit between the spline groove of the half shaft gear and the half shaft, poor meshing of the driving and driven bevel gears, damage of the gear tooth surface or fracture of the gear teeth.

② Stop and check. Set up the rear axle so that one side of the rear wheel is on the ground (and the front and rear wheels are plugged with triangle wood), the other side of the rear wheel is suspended from the ground, and the front wheels on both sides are plugged with triangle wood. Start the diesel engine, put it into gear, add oil and loosen oil to change the speed. If you hear the impact sound at the rear axle, the gear engagement clearance is generally too large; if you hear a strong sound, it may be that the key groove of the axle shaft gear is loose, or the fixed screw between the driven bevel gear and the differential housing is loose; if you hear a more disorderly impact sound, it means that the total clearance of each component is too large. Repeat the test, find out the sound source, compare with the noise when driving, and find out the fault position. It can also remove the main reducer and differential assembly, use a small crowbar to move the gear to check or insert the soft lead wire into the backlash to engage, so as to test the meshing clearance.

③ Stop the diesel engine and check it further. Put the main transmission lever of the gearbox into neutral, lock the wheel brake, and turn the flange of the driving bevel gear shaft left and right by hand to feel the looseness. When the porosity is greater than 5 ° – 6 °. If there is no clearance, it is too small.

④ For continuous noise, touch the rear axle housing (driving and driven bevel gear housing) by hand. If there is heating, the meshing clearance is too small; if it is hot, it is usually lack of oil, check the oil level in the rear axle; if it is only the heating at the bearing, it is too much bearing preload. The main reducer and differential assembly can also be removed, and the driving bevel gear can be moved with a small crowbar for inspection. If there is no activity, or the paper strip can be inserted into the backlash to rotate the gear. To engage, as by biting, a strip of paper through a backlash. That is to say, the gear engagement clearance is too small.

⑤ If the agricultural vehicle suddenly makes abnormal noises during driving, most of them are the damage of rear axle gear or bearing; if the transmission shaft can rotate, but the vehicle can not drive, it is half shaft fracture.

⑥ During the driving of agricultural vehicles, if there is a “creak, creak” intermittent sound, it may be caused by the bending of the axle shaft or axle shaft sleeve, resulting in the collision between the two.