Abstract: The unique structure of a floating cup floating on drum plate in a floating cup axial piston pump leads to possibility of the floating cup overturning. In this study, combined with structural characteristics of the floating cup pump, both the trajectory of the floating cup on the drum plate and the situation that the floating cup overturns under the action of centrifugal force and leads further to stuck in the process of motion are analyzed respectively. The analysis shows that a compression spring may prevent the floating cup from tilting from the drum plate and does not affect the normal movement of the floating cup. The design of the compression spring is also introduced, including the optimum spring radius, the adequate position and size of the plunger hole on the compression spring. Finally, the compression spring is then analyzed numerically by finite element method, and the results show that it is necessary to optimize and improve the structure around the screw hole of the compression spring.

Key words: floating cup pump, floating cup, barrel, hold down spring