broken shaft: replace

worn out- depending on the material, application, extent - weld/plate/sleeve/replace.

No specific answer is possible - all depends on application, stresses, material, effects of the particular type of repair on the shaft and the equipment.

equipment maintenance:-

1)prevantive and predictive maintenance of equipments

2)check list implemted

3)analysis of parameter such as viberation,alignment,smooth running,abnormal temperature and overload on equipments

these are the main factor to minimise the damage of equipments

thanks

rcmandal