Abstract: A hydrostatic cylinder block having a split cylinder block with a slipper hold-down created by breaking down the cylinder block into its basic geometries through near net shaping technology. The cylinder block is broken down into four separate components: a hub, a wave spring, a cylinder block body, and a base plate. Each component is created using near net shaping technologies. The geometries are then placed together to create the completed cylinder block wherein the wave spring separates the hub from the block body to provide an improved slipper hold down force.

Abstract: A method of making a cylinder block for a rotatable hydrostatic power member by separating the cylinder block into its four geometries and joining them together. The geometries include a base plate having a center opening and a arcuate kidney-shaped openings uniformly spaced radially around the center opening. The second geometrical item is a grooved drive shaft that fits into the center opening of the base plate. The third member is a group of tubular bore elements that fit in the base plate and mate with the drive shaft. The final member is a torque ring that matingly fits over the tubular piston bore elements.

Abstract: A method of securing a cap on a piston body includes forming a first annular V-shaped surface at an open end of a cylindrical piston body; forming a second annular V-shaped surface on an annular surface of an oil conduit in the interior center of the piston body; forming a cap to close the open end of the piston body and forming a pair of annular surfaces therein which are flat in shape and in contact with first and second annular V-shaped surfaces on the piston body; placing the cap over the open end of the piston body and thereby placing the annular surface on the cap and the body in close intimate contacting relation; and welding the respective annular surface of the cap and the piston body together by subjecting the cap and body to an extreme high current density to fuse respective contacting annular surfaces together.

Abstract: A method of securing a cap on a piston body includes forming a first annular V-shaped surface at an open end of a cylindrical piston body; forming a second annular V-shaped surface on an annular surface of an oil conduit in the interior center of the piston body; forming a cap to close the open end of the piston body and forming a pair of annular surfaces therein which are flat in shape and in contact with first and second annular V-shaped surfaces on the piston body; placing the cap over the open end of the piston body and thereby placing the annular surface on the cap and the body in close intimate contacting relation; and welding the respective annular surface of the cap and the piston body together by subjecting the cap and body to an extreme high current density to fuse respective contacting annular surfaces together.

Abstract: A closed cavity piston includes an elongated piston body and a separately formed piston cap having an elongated stem and head thereon. The body includes a closed end and an open end with a cavity having a bottom wall adjacent the closed end and an outer wall terminating in a rim at the open end. The stem of the piston cap is friction inertia welded to the bottom wall of the piston body and the head of the piston cap welds to the rim of the piston body so as cover the open end and sealingly enclose the cavity. The piston components can both be formed by conventional and relatively inexpensive cold forming techniques. The stem of the cap is inserted into the cavity of the body until it engages the bottom wall. Then the cap is friction inertia welded to the body at the stem/bottom wall and head/rim interfaces.

Abstract: A method of manufacturing male bimetal slippers includes the steps of forming a stem having opposite first and second ends; rigidly affixing a ball on the first end of the stem to form a male slipper body; and capacitance discharge welding a wear pad to the second end of the stem. To manufacture female bimetal slippers the method includes forming a slipper body of a first material, the body having opposite first and second ends, the first end having a ball socket formed therein; and capacitance discharge welding a wear pad of a second material to the second end of the body.

Abstract: A closed cavity piston includes an elongated piston body and a separately formed piston cap having an elongated stem and head thereon. The body includes a closed end and an open end with a cavity having a bottom wall adjacent the closed end and an outer wall terminating in a rim at the open end. The stem of the piston cap is friction inertia welded to the bottom wall of the piston body and the head of the piston cap welds to the rim of the piston body. The stem of the cap is inserted into the cavity of the body until it engages the bottom wall. Then the cap is friction inertia welded to the body at the stem/bottom wall and head/rim interfaces after preheating.

Abstract: A hydraulic piston for a cylinder block of a hydrostatic power unit has an elongated cylindrical body with first and second ends. An elongated cavity is formed in the body. A cap is adhered to the body to close the cavity. The cap has an external shape to facilitate the operative engagement thereof with a slipper, which is in subsequent engagement with a swashplate mounted adjacent the cylinder block. The piston has an elongated first conduit formed in the body which is separate from the cavity and extends between the opposite ends thereof. The conduit terminates in registering communication with a second conduit in the cap thereof to permit transmission of oil through the conduit without invading the volume of the cavity. The cap preferably has a tapered surface on the inner end thereof engaging a compatible shaped surface on an adjacent end of the body to center and align the cap with the body.

Abstract: A closed cavity piston of this invention includes an elongated piston body and a separately formed piston cap having an elongated stem and head thereon. The body includes a closed end and an open end with a cavity having a bottom wall adjacent the closed end and an outer wall terminating in a rim at the open end. The stem of the piston cap is friction inertia welded to the bottom wall of the piston body and the head of the piston cap welds to the rim of the piston body. The stem of the cap is inserted into the cavity of the body until it engages the bottom wall. Then the cap is friction inertia welded to the body at the stem/bottom wall and head/rim interfaces after preheating.

Abstract: A piston for use in the cylinder block of a hydraulic power unit. The piston has an elongated cylindrical body and one end terminating in a spherical surface. The piston is composed of a body and insert which are made from different materials, preferably metallic materials, and joined together. The piston body takes the form of a solid cylinder or a hollow cylindrical tube. The spherical surface takes the form of an internal spherical socket or an external spherical ball. The insert takes an elongated or abbreviated form providing for both open cavity and closed cavity piston configurations. The piston includes a conduit which traverses the body and insert, providing a path for pressurized fluid. The body and the insert are preferably formed by a metal injecting molding process utilizing a molding material comprised at the time of molding of a mixture of metallic grains and a binder.

Abstract: The present invention relates to a filled piston assembly for a hydraulic pump or motor. The filled hydraulic piston assembly includes a blank piston body having first and second ends and a cavity or compartment in the piston body extending inwardly from one of the ends. The piston is filled with a lightweight solid insert element which is placed into the compartment of the piston. The material of the blank piston body is then cold formed around the insert element to encapsulate the element. The piston body is then further cold rolled to receive a spherical ball in one end. It is then cut to length, machine finished, and a longitudinal center bore is drilled therein.

Abstract: A closed cavity piston assembly includes a piston body, a separately formed piston cap sealingly joined to the body, and an elongated stem integrally formed with one of the piston body or the cap. In one embodiment, the stem is integrally formed with the piston body. In another embodiment, the stem is integrally formed with the piston cap and slidably journaled in and sealed to a hole in the bottom of the piston body. The cap of the piston assembly also has a surface for engaging a slipper. In either case, a fluid passageway extends through the stem, body, and cap of the piston assembly. The passageway is remote from the side wall of the piston body and fluidly isolated from the main interior cavity of the hollow piston body once the cap and body are sealingly joined together. The piston assembly can be pivotally attached to a slipper that has its own fluid passageway, which registers with the passageway in the cap, to provide fluid for slipper lubrication and balance.

Abstract: A piston for use in the cylinder block of a hydraulic power unit. The piston has an elongated cylindrical body and one end terminating in a spherical surface. The piston is composed of a body and insert which are made from different materials, preferably metallic materials, and joined together. The piston body takes the form of a solid cylinder or a hollow cylindrical tube. The spherical surface takes the form of an internal spherical socket or an external spherical ball. The insert takes an elongated or abbreviated form providing for both open cavity and closed cavity piston configurations. The piston includes a conduit which traverses the body and insert, providing a path for pressurized fluid.