Slipper arrangement for hydraulic pump

In a fluid pressure pump of the radial piston type, including a piston having an enlarged spherical head with an axial drilling therethrough which allows fluid flow in through the piston head and a crankshaft having at least one cam lobe, the improvement comprising:

• a slipper including a body having inner and outer surfaces, said inner surface being arcuately shaped for engagement with said cam lobe on said crankshaft, said slipper including an opening therethrough to permit centrifugal flow of fluid through said slipper, said outer surface including a recess retaining a hardened annular seat insert, said insert including an inner circumferential right angle corner which provides a sharp line of contact for engaging and supporting said spherical piston head for articulate movement, said spherical piston head extending into said seat insert, said recess including a bottom wall and said circumferential corner of said insert supporting said piston head above said bottom wall thereby providing substantial open space on both sides of said line of contact between said piston head and slipper to prevent contaminants from entering between the contacting surfaces of said piston head and slipper and said circumferential corner providing a wiping action against said piston head as said piston head moves relative to said slipper.