Take you to understand several methods of judging the abnormal noise of the semi-trailer chassis

18 Mar.,2022

Introduce several methods for judging abnormal noise of semi-trailer chassis:


Introduce several methods for judging abnormal noise of semi-trailer chassis:

1. Discrimination of abnormal sound of engine and abnormal sound of rear axle

First, drive the semi-trailer on a flat road for a certain mileage, so that the working temperature of the rear axle rises to normal. Then when the semi-trailer makes an abnormal noise, record the speed. After parking, put the transmission in the neutral position, and then slowly Accelerate until the speed of the engine is equal to the speed of the vehicle when the abnormal noise occurs, observe whether there is any abnormal noise, and repeat several times to determine whether the abnormal noise is caused by the abnormal condition of the exhaust or the engine. Semi-trailer maintenance maintenance net

2. Distinguishing between tire noise and rear axle noise

Tire noise varies with the road surface, rear axle noise does not. When the speed of the semi-trailer is lower than 48km/h, the rear axle noise disappears, while the tire noise continues. The tire noise is the same when the semi-trailer is driving and coasting, but the rear axle noise is different.

3. Discrimination of abnormal noise of wheel hub bearing and rear axle noise

When the semi-trailer is running and sliding, the noise of the front wheel bearing remains unchanged. If the vehicle speed remains unchanged and a little braking is applied, part of the load on the wheel bearing can be reduced, so that the noise can be reduced, and the source of the noise can be found.

When the vehicle speed is greater than 48km/h, unless the rear wheel axle is seriously damaged, the noise of the rear wheel bearing can rarely be heard. The rear wheel bearing makes a "rustling" sound.

4. Discrimination of abnormal noise of reducer tapered active bearing and differential bearing

Retarder bearings often produce a harsh "rumble" or "quack" sound with a steady beat that varies with vehicle speed.

The noise of the front bearing of the conical driving gear of the reducer is larger when the semi-trailer is sliding, and the noise of the rear bearing is larger when it is driving.

The noise of the differential bearing is usually a constant screeching noise, but its beat is much more moderate than the noise of the reducer bevel drive gear bearing.

5. Discrimination of rear axle gear noise

During normal straight driving, no noise can be heard since there is little relative movement between the differential side gears and the planetary gears.

During the driving of the semi-trailer, the reason for the abnormal noise of the rear axle gear is mostly caused by poor lubrication, which leads to the wear of the reducer gear. If the abnormal noise can be heard at various sliding speeds, it means that the deceleration It is caused by the looseness of the nut of the drive gear.

At low speed, there is a knocking sound at the rear axle, and when accelerating or decelerating, it makes a particularly dull abnormal sound. The cause of the above failure can be found in one or more of the following:

Improper clearance between differential side gear journal and differential case.

Improper fit between differential cross journal and differential case.

Improper backlash between the side spline gear and the differential side gear keyway.

The meshing backlash between the differential side gear and the planetary gear is improper.

The differential cone active and passive gear meshing backlash is improper.

Worn thrust washers.

When the vehicle is running, the abnormal sound of the rear axle is caused by improper gear meshing clearance, improper adjustment of differential bearing preload or both. When eliminating abnormal noises, it is necessary to disassemble and check the meshing clearance between the differential gear and the reducer gear, the preload of the reducer bevel drive gear bearing and the contact traces of the reducer gear.