How to analyze the failure of the rear axle axle shaft

The rear axle axle is the partial speed axle that drives the wheels of the car, and is located in the axis of the rear axle. The inner end of the half shaft spline shaft and the differential half shaft gear spline sleeve set, the outer end flange of the half shaft and the wheel are fastened and assembled with studs, nuts and tapered bushings.
The two half shafts can be driven at the same speed or at different speeds under different working conditions during transmission. Abnormalities in the rear axle housing, differential, wheels, etc. will affect the normal transmission of the axle shafts, wear and break the axle shafts, and even cause unpredictable losses to the vehicle. In addition to the overload of the vehicle and the increase of the rear transmission load caused by the driver's careless manipulation, the damage of the rear axle shaft of the automobile has the following aspects:
(1) Damage to the inner end of the half shaft
①The keyway of the spline shaft is tapered along the groove tooth length, steps, tooth surface deformities, etc., due to the looseness of the side gear bearing hole of the differential case and the side gear, the differential bearing is loose, and the rear wheel bearing is loose. Wait;
② Wear of the journal at the inner end of the axle shaft and the appearance of grooves on the axle surface are due to the looseness of the axle gear bearing hole of the differential case and the axle shaft, and the damage of the differential bearing.

(2) The middle part of the semi-axle is bent and abraded, and the hair surface of the shaft is in contact with the inner wall of the rear axle steel pipe. This is due to the deformation of the rear axle housing, cracks, the bending of the rear axle steel pipe, the loosening of the steel pipe and the rear axle housing, etc., making the rear axle housing The axis of the rear half shaft is offset.
(3) Cracks and breaks occurred in the middle part of the axle shaft and the root of the flange. Except for the forging and pressure scars of the original axle shaft during the manufacturing process, it was mainly due to the deformation and bending of the rear axle housing, the loosening of the steel pipe and the rear axle housing, and the loosening of the rear wheel bearing. The wide swing is so poor that the semi-shaft swings abnormally during transmission.
(4) The damage of the half shaft flange stud with nut and the tapered bushing is caused by the deformation and bending of the rear axle housing, the bending of the half shaft, and the looseness of the rear wheel bearing. The main reason is that the tapered bushing is less installed (Af ), or Af is too small or too short, so that the flanged stud with nut and Af is excessively stressed from the direction of rotation, and the screw hole on the flange plate and the Af seat hole are worn and enlarged, and the threaded hole of the stud Loose, the contact surface between the flange plate and the wheel is worn out, and even all the bolts are cut off. Damage to these parts of the semi-axle flange will often increase the transmission void of the semi-axle and cause the semi-axle to break.

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