汽车传动轴的技术状况变坏时，弯曲振动的振幅增大，振动剧烈，甚引起车身振抖，并发出明显的周期性响声，即称为振抖和异响汽车传动轴随着车速的增高而加剧，传动轴产生振抖和异响的主要原因有以下几个方面。

When the technical condition of the automobile transmission shaft deteriorates, the amplitude of bending vibration increases, the vibration is severe, and even causes the body to vibrate and produce obvious periodic sounds, which are called vibration and abnormal noise. The automobile transmission shaft intensifies with the increase of vehicle speed, and the main reasons for the vibration and abnormal noise of the transmission shaft are as follows.

传动轴总成失去平衡

Transmission shaft assembly out of balance

传动轴总成的装配误差超限、零件尺寸不精确及在使用中的磨损变形等都会使传动轴沿长度方向的质量分布不均匀而造成传动不平衡。不平衡的传动轴在运转中便会产生附加弯矩，附加弯矩的作用不仅会使配合件冲击发响，还会增强传动轴的弯曲振动，使传动轴的振抖和异响更为明显。

The assembly error of the transmission shaft assembly exceeds the limit, the size of the parts is not accurate, and the wear and deformation during use can cause uneven distribution of mass along the length direction of the transmission shaft, resulting in transmission imbalance. An unbalanced transmission shaft will generate additional bending moments during operation. The effect of the additional bending moment not only causes the mating parts to impact and make noise, but also enhances the bending vibration of the transmission shaft, making the vibration and abnormal noise of the transmission shaft more obvious.

万向节损伤

Universal joint damage

万向节在使用中的主要损伤是十字轴轴颈和端面磨损及滚针和轴承座孔磨损等。万向节零件的损伤使十字轴配合松旷而产生摆动和轴向窜动，不仅在工作中发出撞击声，而且削弱传动轴的抗弯刚度。传动轴的质量中心更加偏离旋转轴线，从而增强振抖和异响。

The main damage to the universal joint during use is the wear of the cross shaft journal and end face, as well as the wear of the roller needle and bearing seat hole. The damage to the universal joint components causes the cross shaft to fit loosely, resulting in swinging and axial displacement. This not only makes a collision sound during operation, but also weakens the bending stiffness of the transmission shaft. The center of mass of the transmission shaft deviates further from the rotational axis, thereby enhancing vibration and abnormal noise.

传动轴和滑动叉损伤

Damage to transmission shaft and sliding fork

传动轴轴管弯曲，即增大传动轴弯曲振动的振幅，可使离心力增大，从而造成强烈的振抖和异响。传动轴键齿和滑动叉键槽磨损，由于配合松旷，在工作中会发出撞击声，还会削弱传动轴的抗弯刚度，增强振抖和异响。

Bending of the transmission shaft tube, which increases the amplitude of the bending vibration of the transmission shaft, can increase the centrifugal force, causing strong vibration and abnormal noise. The key teeth of the transmission shaft and the sliding fork keyway are worn, and due to loose fit, there will be a collision sound during operation, which will weaken the bending stiffness of the transmission shaft, enhance vibration and abnormal noise.

传动轴两端的安装位置改变

Change in installation position at both ends of the drive shaft

对于不等角速万向节传动轴而言，为减小传动轴的振动和保证驱动桥齿轮的匀速转动，必须符合以下2个条件：

For unequal angular velocity universal joint drive shafts, in order to reduce vibration of the drive shaft and ensure uniform rotation of the drive axle gears, the following two conditions must be met:

传动轴两端的万向节叉应位于同一平面内；

The universal joint forks at both ends of the transmission shaft should be located in the same plane;

输入轴、输出轴与传动轴的两夹角应相等。 传动轴在使用中，由于传动轴键齿和滑动叉键槽磨损，万向节十字轴轴颈与滚针配合松旷等，会使1条件破坏；而传动轴安装不良、弹性</a悬架技术状况变化及传动轴的输入轴和输出轴磨损使安装位置改变等，均会使第2条件破坏。 随着等速传动条件的破坏，将使驱动桥主减速齿轮产生冲击，并引起传动轴运转不稳定，增强抖动和异响。

The angle between the input shaft, output shaft, and transmission shaft should be equal. During use, the transmission shaft may be damaged due to wear on the key teeth and sliding fork keyway, as well as loose fit between the universal joint cross shaft neck and the rolling needle; Poor installation of the transmission shaft, changes in suspension technology due to elasticity, and changes in the installation position caused by wear of the input and output shafts of the transmission shaft can all cause the second condition to be damaged. With the destruction of constant speed transmission conditions, it will cause impact on the main reduction gear of the drive axle, and cause unstable operation of the drive shaft, enhancing vibration and abnormal noise.

传动轴临界转速降低

The critical speed of the transmission shaft decreases

传动轴设计时的高转速一般为临界转速的 0．7倍。但由于传动轴动平衡的破坏、万向节的损伤及中间支承轴承松旷等，都会使传动轴临界转速降低。当临界转速降低到传动轴的转速时，传动轴在运转中便易于产生共振。传动轴共振时的振幅大，振动剧烈，往往会造成传动轴折断。

The high speed during the design of the transmission shaft is generally 0.7 times the critical speed. However, due to damage to the dynamic balance of the transmission shaft, damage to the universal joint, and looseness of the intermediate support bearing, the critical speed of the transmission shaft will decrease. When the critical speed drops to the speed of the drive shaft, the drive shaft is prone to resonance during operation. When the transmission shaft resonates, the amplitude is large and the vibration is severe, often causing the transmission shaft to break.