1) There are indentations on the inner and outer rings of the support bearings of the transmission gear gear.
Possible cause: Improper bearing selection.
After the gear gear is shifted into gear, the radial force generated by the torque is transmitted through the static ball bearing. The balls are in point contact with the inner and outer rings. When an overload occurs, a huge radial force at one point causes plastic deformation at the contact point between the inner and outer rings and the balls. The vibration impact fork during rolling causes the plastic deformation zone to continuously expand.
Check points: First, find the bearings with fault signals through the vibration monitoring system. Put all gears in the neutral position and hand-operate the gears. If you hear or feel continuous intermittent vibration, you can initially determine that there are indentations on the inner and outer rings of the support bearing.
Solution: When replacing the bearing, preload 300~500N force in the axial direction. Eliminate axial clearance.
2) The tooth surface of the gearbox spline shaft is worn, making it difficult to shift into gear. The reason is that the tooth surface hardness of the clutch spline sleeve is too high. Under overload conditions and vibration impact during rolling, the indentation and wear of the spline shaft tooth surface occur earlier than the spline sleeve.
Solution: Disassemble the gear shaft and grind the spline tooth surface. Increase the lubrication oil supply of spline teeth.
3) Some gearbox cases are not rigid enough.
Solution: Strengthen the rigidity of the box or replace the box.