Reasons For The Gear Shaft Fracture of Planetary Reducer

- Dec 21, 2020-

Planetary reducer is widely used in the field of industrial equipment, and its work performance is highly integrated, which attracts many users. However, it need to be maintained carefully during usage. Due to its long-term operation, there will be some wear and other failures. A common fault of planetary reducer is the broken gear shaft. Now, let's take a look at the causes of gear shaft fracture.


vibration and noise warn users the gear bearing fracture of the planetary reducer. When we check the planetary reducer inside, we often find out that the meshing gears in the reducer are broken, the tooth surface is severely worn, and the gear gap become too large. Some reducers lack lubricating oil and cannot produce oil film between the meshing teeth; The bearing is damaged, etc., all these cause vibration and noise.


One reason caused this phenomenon is that in terms of material selection, the shaft diameter should be adapted to the torque transmitted by the planetary reducer, and it should use the quenched and tempered steel with high hardenability.  Analyzing the metallographic spectrum it is known that the material of the pinion shaft is loose and there are many inclusions, which will reduce the impact toughness, and under high-speed variable load, the existing cracks rapidly expand, resulting in the shaft fracture.


Secondly, the force analysis of the gear shaft shows that the gear shaft bears large torque and bending moment during operation. Torque generates shear stress, and bending moment generates normal stress on the shaft. These stresses are constantly changing during shaft operation. It’s symmetrical cyclic alternating stress and additional dynamic load. If it encounters vibration, excessive load, sudden start and braking, and multiple heavy load impacts, the shaft may cracks and breaks.