Abstract: A port plate is disclosed for use with an axial pump. The port plate may have a cylindrical plate member with a head-end face and a piston-end face located opposite the head-end face, at least one inlet port formed within a first half of the plate member and extending from the head-end face through the piston-end face, and at least one outlet port formed within a second half of the plate member and extending from the head-end face through the piston-end face. The port plate may also have at least one timing hole formed within the plate member at a leading end of the at least one outlet port and passing from the head-end face through the piston-end face, and an arcuate spherical groove extending from the at least one timing hole to the at least one outlet port.

Abstract: An axial piston hydraulic device includes a holddown device for maintaining the slippers swivably connected to pistons in sliding contacting with a cam surface of a swashplate. The holddown device also includes a nested wave spring disposed to resiliently urge a holddown sleeve away from a cylinder barrel for biasing a holddown plate engaging the slippers toward the cam surface.

Abstract: A follow up mechanism for maintaining a timed positional relationship between a bearing cage of an arcuate roller bearing assembly and a swashplate supported by the bearing assembly includes a flexural elastic link pivotally connected to the bearing cage and having first and second ends slidably disposed within a first bore in a pump housing and a second bore in the swashplate, respectively. The bores are in axial alignment with each other when the swashplate is in the equivalent of its centered position thereby allowing blind assembly of the follow up mechanism thereby eliminating the need for an access opening in the side of the pump housing and the associated cover, gasket and bolts.