During the whole machine strengthening test of the underground loader, the chassis makes abnormal noise. The specific situation is as follows: when the steering wheel is turned when the engine is running at idle speed, a part of the chassis will make a crisp metal impact sound, and it is uncertain where the steering wheel makes abnormal noise; When the accelerator is pressed to accelerate, the sound becomes weak or basically disappears.

根据该机故障现象和对其转向系统结构的分析，我们认为其机架、转向液压系统、变速器出现故障的可能性很小，该异响可能来源于以下3方面：一是传动轴伸缩时产生异响，二是主减速器和差速器异响，三是后桥摆动架异响。

According to the fault phenomenon of the machine and the analysis of its steering system structure, we believe that the possibility of failure of its frame, steering hydraulic system and transmission is very small, and the abnormal noise may come from the following three aspects: first, the abnormal noise generated during the expansion and contraction of the transmission shaft, second, the abnormal noise of the main reducer and differential, and third, the abnormal noise of the swing frame of the rear axle.

（1）排查传动轴

(1) Check the drive shaft

后桥在摆架上摆动时，后桥中心的输入法兰也会随后桥摆动，使后传动轴的长度及空间位置发生变化。检查发现装载机在转向过程中，后传动轴并不会发生明显伸缩，该处无存在异响的可能性。

When the rear axle swings on the swing frame, the input flange in the center of the rear axle will also swing with the rear axle, changing the length and spatial position of the rear transmission shaft. It is found that during the steering process of the loader, the rear drive shaft will not expand significantly, and there is no possibility of abnormal sound.

（2）排查主减速器和差速器

(2) Check the final drive and differential

在后驱动桥的轮边减速器位置用手触摸能感觉到有撞击动作。我们更换了主减速器和差速器总成，经试机异响问题依然没有。

At the wheel reducer position of the rear drive axle, the impact action can be felt by hand. We replaced the main reducer and differential assembly, but the problem of abnormal noise still hasn't been solved after commissioning.

（3）扫卜查后桥摆架

(3) Sweep the rear axle swing frame

为了模拟异响时的工状，并能实时观察前、后摆动架的实际运行情况，我们将该装载机开到检修平台上。通过多次原地转向、进退行驶试验，仔细观察摆架状态，发现后摆动架与桥壳之间有3mm相对窜动。正是由于后连接法兰在后摆动架的窜动，引发了后摆动架与后桥壳上的连接法兰相互撞击，从而产生了异响。

In order to simulate the working state in case of abnormal noise and observe the actual operation of the front and rear swing frames in real time, we drive the loader to the maintenance platform. Through many in-situ steering, forward and backward driving tests, carefully observe the swing frame state, and it is found that there is 3mm relative movement between the rear swing frame and the axle housing. It is the movement of the rear connecting flange on the rear swing frame that causes the rear swing frame and the connecting flange on the rear axle housing to collide with each other, resulting in abnormal noise.

找到异响发生位置后，我们分析产生该间隙的原因。查阅后桥图纸，并从后桥的供应商那里的到了相关情况。该型装载机后桥桥壳与后摆动架的理论设计间隙为1.1～2.15mm，安装时的调整垫片只有厚度为6mm的1种规格。实际拆检出现异响的这台装载机，测量其调整垫片厚度只有5.1mm。再加上设计间隙，总共累积成3mm间隙。

After finding the location where the abnormal sound occurs, we analyze the cause of the gap. Refer to the rear axle drawing and get the relevant information from the rear axle supplier. The theoretical design clearance between the rear axle housing and the rear swing frame of this loader is 1.1 ~ 2.15mm. During installation, there is only one specification with a thickness of 6mm. The loader with abnormal noise was actually disassembled and inspected, and the thickness of its adjusting gasket was only 5.1mm. In addition to the design clearance, the total accumulated clearance is 3mm.