Axle failure analysis: Rear axle abnormal sound, oil leakage how to do?

All along, when judging the power performance of a car, the first thing to look at is the engine, gearbox and axle of this car, which is often referred to as the "three big parts", and it is these three parts that together form the power chain of the truck.

We have talked about the engine and gearbox in several previous articles, and today we will talk about the composition and common faults of this last big axle.

To solve the problem of the axle, we must first understand what is the axle, Baidu Encyclopedia gives the explanation is: "Through the suspension and the frame is connected, the wheels are installed at both ends, mainly to bear the load of the car, to maintain the normal driving of the car on the road."

This may be a general statement, but the description is intuitive. But in addition to carrying the load of the truck, it will also transfer the traction or braking force of the wheel and the side force to the frame through the suspension. That is to transfer the forces in all directions between the frame or the bearing body and the wheel and the bending moment and torque generated by it.

● Classification of axles

There are many types of axles, according to their different uses, axles can be divided into steering axle, drive axle, steering drive axle and support bridge 4 types, which can be divided into drive axle and driven axle according to there is no power output.

Things like steering Bridges and support Bridges are driven Bridges, that is, being carried around. General trucks are rear drive, so the front axle is mostly the steering axle, and the rear axle or the middle and rear two Bridges are the drive axle.

Steering axle

The steering axle, as its name suggests, uses the steering knuckles to deflect the wheels, thereby enabling the car to steer. In addition, it is also necessary to bear the vertical load between the wheel and the frame and the longitudinal road resistance.

Axle failure analysis rear axle abnormal sound, leakage is what happened

The steering bridge is mainly composed of: bridge, kingpin, steering knuckle, wheel hub, brake, generally a traditional reverse bending I-beam, the production process is relatively simple, each end has a fist shaped part, with a through hole, through the kingpin and the left and right steering knuckle connection, with a threaded wedge lock pin fixed in the front shaft hole, so that it can not be rotated relative to the front shaft.

When the car turns, the steering rocker arm swings in the longitudinal plane, through the steering straight tie rod, steering knuckle arm, left trapezoidal arm, steering cross tie rod and right trapezoidal arm, manipulate the front wheel of the car to turn a certain Angle, so as to change the direction of the car.

Drive axle

Generally speaking, the rear axle of the truck is the drive axle, which mainly carries the load of the rear part of the truck, and also needs to complete the power transmission between the transmission shaft and the gearbox, the power deceleration and torque of the engine output, and the main reducer and semi-shaft output to the wheel after changing the transmission direction.

Axle failure analysis rear axle abnormal sound, leakage is what happened

The composition of the drive axle will be relatively complex, it is located at the end of the drive train, mainly composed of the main reducer, differential, wheel transmission and drive axle housing.

Moreover, it should be noted that there are many kinds of drive axle, including drive axle, steering drive axle and electric drive axle. The steering drive axle has a steering function, and the electric drive axle is a relatively new thing. The motor and reducer are integrated on the axle, so the components of the vehicle can be reduced, the total weight of the vehicle can be reduced, and the transportation efficiency can be improved.

Support bridge

Supporting the bridge is relatively simple, it has no driving function and can't steer, it only needs to bear the vertical load of the truck and the longitudinal and lateral forces and the torque caused by these forces. Like single-axle driven three-axle vehicles, the rear axle is generally set as a support axle. Of course, the trailer axles are all support Bridges.

● Drive axle deceleration function

From the above, we can know that during the driving process, the drive axle undertakes the most tasks and the composition is more complex. Also worth mentioning here is its deceleration function.

Axle failure analysis rear axle abnormal sound, leakage is what happened

Of course, the deceleration we are talking about here is actually reducing the high speed of the engine output. That is, through the reducer, the high speed output of the engine is converted into the low speed used in the wheels. We often say that the speed ratio is the ratio between the speed output of the engine and the speed output of the reducer.

So why lower the RPM? This is done to amplify the torque of the engine and make the truck run more powerful, just like everyone knows that you need to downshift when going uphill.

● Axle common failure and reasons:

As the three components of the truck power company, the axle is absolutely heavy work, so in the daily use process, especially the drive axle will often encounter some failures, the most common is mainly abnormal noise, high temperature and oil leakage of these three categories.

Abnormal Noise:

Failure performance: When you step on the accelerator to accelerate or step on the brake to slow down, the vehicle will make a "buzz" sound.

Failure cause: axle's active bevel gear and passive bevel gear meshing mark is not suitable.

Fault performance: When the vehicle accelerates, the knocking sound of "dang, dang, dang" comes from the axle bridge.

The cause of the failure: the gear has been broken, the tooth surface spalling, pitting and other problems.

Fault performance: During normal driving, a harsh noise was emitted.

Failure cause: This is the main reducer inside the bearing corrosion, spalling, wear, scattered, ablative failure situation.

Fault performance: there is no problem in the normal straight line driving process, but it will emit abnormal sound when turning.

Failure cause: differential damage.

Heat:

Fault performance: the temperature of the reducer housing is higher than 120℃. This is often said that the axle heat, if not dealt with in time may lead to vehicle fire.

Failure cause: too much or too little fuel. When the amount of fuel is too much, the heat generated by the drive axle is difficult to disperse; When the amount of fuel is too small, it will also cause heat because of insufficient lubrication.

Oil spill:

Failure performance: The oil leakage here is the main reducer oil leakage.

Failure cause: The input oil seal is damaged, which is also the main reason for the oil leakage of the main reducer.

The cause of the failure: the axle vent is blocked, and there will be a vent on the axle, but when the vent is blocked, high temperature and high pressure will be generated inside the axle, and under the action of high pressure, the lubricating oil will be pressed out.

As one of the "three major parts" of the truck, the axle is a very important component, which not only carries the full weight of the truck, but also is responsible for the steering, driving, braking and other functions of the vehicle. So here also remind the owners, in the usual driving time must regularly check, eliminate the rear axle fault.