Although many tribology references have presented the Reynolds equation in cylindrical coordinates, they may not be applicable to the slipper/swash plate interface in axial piston pumps due to complex macro and micro motions of slippers. Therefore, this paper derives the generalized Reynolds equation in cylindrical coordinates for this interface from momentum and continuity equations. Also, the boundary velocity conditions for the Reynolds equation are evaluated based on the kinematics of slippers, which accounts for the spinning motion. Compared with the traditional Reynolds equation for the slipper/swash plate interface, the new Reynolds equation in this work considers the geometric squeeze and centrifugal terms and has a different form of Couette terms.
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