Air compressor spindle fracture can be caused by the following factors:

1.Design and quality issues: If the spindle design is underdimensioned, the material is not strong enough, or there are manufacturing defects, it can cause breakage. For example, the design of the center oil injection hole may weaken the strength of the input shaft, or the radial dimension of the input shaft of the shaft head pump may be insufficient, which can lead to torsion.

2.Installation error: If the main oil pump is installed improperly or the pump body is installed eccentricly, additional torque will be generated during the operation of the oil pump shaft, which in turn will cause the main shaft to break.

3.Additional Loads and Torques: Eccentric mounting can subject gear bearings to additional moments and loads, increasing the risk of spindle breakage.

4. The influence of high speed: too high speed may cause high-frequency bending and torsion of the gear shaft, resulting in a local temperature increase, reducing the strength of the material, and eventually leading to the fracture of the spindle.

5. Thermal deformation and material resistance: At high temperatures, the shaft structure may undergo thermal deformation, reducing the strength of the material. At the same time, the bending moment can cause the hollow shaft to collapse and deform, providing space for the key to cut, which can lead to spindle breakage.

6. Metallurgical defects and cracks: There may be metallurgical defects and macroscopic cracks inside the motor shaft substrate, which may originate from the inside and extend outward, eventually leading to spindle fracture.

7. Material and heat treatment problems: Material defects, such as sand holes and shrinkage porosity in castings, or insufficient heat treatment, especially in fillet where they are not properly treated, may lead to stress concentration and increase the possibility of spindle breakage.

8. Overload and overspeed operation: Long-term overload operation or unlimited increase in speed to increase output may lead to deterioration of the stress condition, which can cause the spindle to break.

9. Oil circuit failure: The displacement of the bearing may cause the internal oil circuit of the air compressor to be blocked, or the oil supply is insufficient, resulting in the spindle locking or breaking due to lack of oil.

In order to prevent and solve these problems, the following measures should be taken: improve the tooling requirements, improve the machining accuracy, ensure the correct alignment of the oil pump gear shaft, strengthen the base structure of the drive motor for testing, and optimize the design of the gear shaft. Through these methods, the risk of spindle breakage can be reduced and the stable operation of the air compressor can be ensured.