Abstract: A piston-slipper assembly and method for assembling a piston-slipper assembly for use in a hydraulic apparatus such as a piston motor or piston pump. The assembly contains a piston and a slipper, and at least one of the piston or the slipper includes a ball and the other includes a socket. The ball is retained in the socket without crimping, swaging or bending of the socket.

Abstract: A piston-slipper assembly and method for assembling a piston-slipper assembly for use in a hydraulic apparatus such as a piston motor or piston pump. The assembly contains a piston and a slipper, and at least one of the piston or the slipper includes a ball and the other includes a socket. The ball is retained in the socket without crimping, swaging or bending of the socket.

Abstract: A system and method of controlling the rate of pump out of liquid coolant from a sump tank in which the level of liquid coolant in the sump tank is continuously sensed and corresponding signals transmitted to a variable frequency drive controller which correspondingly varies the speed of a pump motor to continuously increase or decrease the pump out rate in correspondence with the level liquid in the sump tank.

Abstract: A variable displacement hydraulic axial piston machine includes (a) a housing having an outlet opening; (b) a barrel mounted in the housing for rotation about a rotation axis; (c) a plurality of pistons movable in respective bores in the barrel; (d) a valve plate coupled to the barrel and having a fluid passage therein that ends at an outlet opening; and (e) a flow tube connecting the outlet opening in the valve plate to the outlet opening in the housing. The barrel and the valve plate are pivotally movable together about a pivot axis transverse the rotation axis for varying the displacement of the pistons in the bores. An end of the flow tube connects to the valve plate while allowing for axial movement of the flow tube relative to the valve plate in a direction parallel to the rotational axis of the barrel.

Abstract: A hydraulic apparatus comprises a housing having a central axis; a plurality of radially-oriented piston-cylinder assemblies each including a cylinder supported by the housing and a piston movable within the cylinder, the piston separating radially inner and outer chambers within the cylinder; and valving and associated flow passages for individually controlling the flow of hydraulic fluid to and from the radially inner and outer chambers of each piston-cylinder assembly. The piston-cylinder assemblies are mounted to the housing for pivotal movement by trunnions provided with flow passages for connecting the piston-cylinder assemblies to inlet and outlet ports via the valving and porting.

Abstract: In a variable displacement type hydraulic pump/motor assembly including at least one internally movable component, such as a yoke, a swashplate, and the means for moving the swashplate, the improvement includes imparting on this component absolute location indicia markings and the addition of an optical/electronic sensor unit capable of reading such indicia markings fixedly located on a housing of the pump/motor assembly and including an optical read head extending into the housing interior and located at a spaced distance from the indicia markings for reading same, relative to a reference location, and producing a signal indicative of the absolute position of the movable component. The signal can then, in turn, be used for controlling the displacement of the pump/motor assembly. A method for determining the absolute component position is also set forth.

Abstract: An axial piston pump that enables fluid entering the pump to be pre-charged without the addition of an auxiliary pumping mechanism or other type of external fluid precharge, comprises a housing having a cylindrical inner wall surface surrounding a barrel chamber, a barrel mounted for rotation within the barrel chamber in the housing and having a plurality of circumferentially spaced piston bores therein, and a plurality of pistons reciprocally movable in the piston bores for pumping fluid from a delivery passage to an exhaust passage. The barrel has at least one and preferably plural impeller vanes projecting radially outwardly and terminating at a radially outer vane edge adjacent the inner wall surface of the barrel chamber. Upon rotation of the barrel, the impeller vanes function to supercharge the fluid supplied to the piston bores.

Abstract: An axial piston pump that enables fluid entering the pump to be precharged without the addition of an auxiliary pumping mechanism or other type of external fluid precharge, comprises a housing having a cylindrical inner wall surface surrounding a barrel chamber, a barrel mounted for rotation within the barrel chamber in the housing and having a plurality of circumferentially spaced piston bores therein, and a plurality of pistons reciprocally movable in the piston bores for pumping fluid from a delivery passage to an exhaust passage. The barrel has at least one and preferably plural impeller vanes projecting radially outwardly and terminating at a radially outer vane edge adjacent the inner wall surface of the barrel chamber. Upon rotation of the barrel, the impeller vanes function to supercharge the fluid supplied to the piston bores.