PREDICTING THE BEHAVIOR OF SLIPPER PADS IN SWASHPLATE-TYPE AXIAL PISTON PUMPS

This paper describes a dynamic model for slipper-pads that allows lift and tilt behavior to be predicted, including the effects of possible contact with the swashplate or slipper retaining plate. This model has been incorporated in the Bathfp simulation package and used to examin e the dynamic stability of slipper-pads over the pumping cycle, and to compare the behavior over a range of pump speeds. The centripetal til ting moments acting on the slipper-pad increase with speed and as a co nsequence can lead to contact between the shipper and the swashplate a t high speed. This is particularly likely to occur as the piston makes the transition between suction and delivery, where the pressure force s acting on the piston-slipper assembly change abruptly. The predicted nature of the swashplate contacts at high speeds correspond closely w ith witness marks on a dismantled pump. The model presented may also b e used for predicting slipper behavior in other types of pump, for exa mple, wobble-plate type pumps, or in piston motors.