Shaft protecting sleeve
The shaft protecting sleeve is fitted to the shaft and rotates in the bearing bush. It protects the pump shaft against mechanical damage caused by shaft seals and bearing shells (see Plain bearing) and against chemical damage caused by aggressive fluids (see Material selection).
When designing the shaft protecting sleeve, care should be taken that any fluid handled that might penetrate the gap between the shaft protecting sleeve and the shaft cannot leak into the atmosphere. Sufficient axial space for expansion must be available and the shaft protecting sleeve (ideally at the impeller end) must be secured against tangential and axial displacements in relation to the shaft.