Abstract: A valve for use in regulating the flow of fluid between a first and a second fluid side is provided. The valve comprises a valve body and an aperture extending through the valve body. The aperture comprises an inner wall, a first aperture diameter at the first end of the aperture and a second aperture diameter at the second end of the aperture. The valve further comprises a first valve insert positioned in the aperture with a first insert diameter and a first mating feature. The first insert diameter is larger than the first aperture diameter. The valve further comprises a second valve insert having a first width, a second width and a second mating feature. The first width is larger than the second aperture diameter. The first mating feature cooperates with the second mating feature to engage the first valve insert to the second valve insert.

Abstract: A dual pump apparatus for use on a vehicle or industrial application and having a pair of hydraulic pumps that are disposed in separate chambers within a housing. A pair of input shafts are disposed within the housing to drive the respective hydraulic pumps and one of the input shafts engages a prime mover. A charge pump may be mounted on an end cap, and trunnion arms for controlling the hydraulic pumps may extend out of opposite sides of the housing. An auxiliary pump may also be mounted on one of the input shafts and may be located either at the input end thereof or on the opposite side of the housing.

Abstract: A hydraulic pump apparatus having an internal sump formed by a housing having an internal portion and an end cap secured to the housing. A rotatable cylinder block is located in the sump and driven by an input shaft extending into the housing. The pump apparatus also has a system of hydraulic porting in fluid communication with the cylinder block. The porting includes a pair of system ports located on a first side of the hydraulic pump apparatus, a fluid inlet on a second side of the hydraulic pump apparatus, opposite the first side, and a bypass valve positioned on the second side adjacent to the fluid inlet.

Abstract: A valve apparatus is disclosed for use in regulating the flow of fluid between a closed hydraulic loop and a fluid source in a hydraulic circuit, where the valve apparatus provides up to four different functions including a check valve, a neutral valve, a relief valve and a pressure rise rate valve. The apparatus includes a valve seat for selectively permitting fluid communication between the closed hydraulic loop and the fluid source, a sleeve member and a relief poppet in the valve seat, a relief compression spring inside the sleeve and positioned adjacent the relief poppet and the base of the slidable member, a valve guide and an accumulator piston slidably mounted within the valve guide to define an accumulator volume therein.

Abstract: A combination check valve and pressure relief valve is provided for use in regulating the flow of fluid between a first fluid side and a second fluid side. The valve may include a valve body, a valve insert positioned within an aperture of the valve body, a check poppet attached to the valve insert, and a check spring positioned between the valve insert and the valve body. In addition, a relief spring and a relief poppet may be positioned within a cavity formed by the valve insert and secured in position by the check poppet. The combination of the valve insert and the check poppet is adapted to move relative to the valve body and against the force of the check spring to permit fluid to pass from the first fluid side to the second fluid side, and the relief poppet is adapted to move relative to the check poppet against the force of the relief spring to allow fluid to pass from the second fluid side to the first fluid side.

Abstract: A charge pump for hydraulic drive device such as a hydrostatic transmission or integrated hydrostatic transaxle using hydraulic porting having first and second pressure sides mounted in a sump to connect a hydraulic pump and motor. The charge pump comprises a body connected between the first and second pressure sides of the porting to pull hydraulic fluid from a charge sump to the low pressure side of the porting, when the second pressure side is under low pressure.

Abstract: A valve for use in regulating the flow of fluid between a first fluid side and a second fluid side of a hydraulic circuit. A bore is extended through a valve seat, and the bore and valve stem cooperate to form a fluid passage from the first side to the second side. A plurality of ribs are located on one side of the valve seat and extend in a direction generally parallel to the bore.

Abstract: A dual pump apparatus for use on a vehicle or industrial application having a housing in which a pair of hydraulic pumps are mounted, having a cooling fan mounted on the primary or secondary input shaft on the opposite side of the pulley used to engage the prime mover. A charge pump may be mounted on the end cap, and the trunnion arms for controlling the hydraulic pumps extend out of opposite sides of the housing. An auxiliary pump may also be mounted on the primary input shaft and may be located either at the input end thereof adjacent to the pulley, or on the opposite side of the housing.

Abstract: A hydraulic pump apparatus having an internal sump formed by a housing having an internal portion and an end cap secured to the housing. A rotatable cylinder block is located in the sump and driven by an input shaft extending into the housing. The pump apparatus also has a system of hydraulic porting in fluid communication with the cylinder block. The porting includes a pair of system ports located on a first side of the hydraulic pump apparatus, a fluid inlet on a second side of the hydraulic pump apparatus, opposite the first side, and a bypass valve positioned on the second side adjacent to the fluid inlet.

Abstract: A hydraulic pump apparatus having an internal sump formed by a housing having an internal portion and an end cap secured to the housing. A rotatable cylinder block is located in the sump and driven by an input shaft extending into the housing. The pump apparatus also has a system of hydraulic porting in fluid communication with the cylinder block. The porting includes a pair of system ports located on a first side of the hydraulic pump apparatus, a fluid inlet on a second side of the hydraulic pump apparatus, opposite the first side, and a bypass valve positioned on the second side adjacent to the fluid inlet. A case drain may also be formed on a third side of the pump apparatus.

Abstract: A charge pump for hydraulic drive device such as a hydrostatic transmission or integrated hydrostatic transaxle using hydraulic porting having high and low pressure sides mounted in a sump to connect a hydraulic pump and motor. The charge pump comprises a body connected between the high and low pressure sides of the porting to pull hydraulic fluid from a charge sump to the low pressure side of the porting.

Abstract: A valve assembly for use in regulating the flow of fluid between a first fluid side and a second fluid side of a hydraulic circuit. The valve includes a valve guide, a valve stem engaged to the valve guide and a valve seat. A bore is extended through the valve seat, and the bore and valve stem cooperate to form a fluid passage from the first side to the second side.

Abstract: A combination check valve and pressure relief valve is provided for use in regulating the flow of fluid between a first fluid side and a second fluid side. The valve may include a valve body, a valve insert positioned within an aperture of the valve body, a check poppet attached to the valve insert, and a check spring positioned between the valve insert and the valve body. In addition, a relief spring and a relief poppet may be positioned within a cavity formed by the valve insert and secured in position by the check poppet. The combination of the valve insert and the check poppet is adapted to move relative to the valve body and against the force of the check spring to permit fluid to pass from the first fluid side to the second fluid side, and the relief poppet is adapted to move relative to the check poppet against the force of the relief spring to allow fluid to pass from the second fluid side to the first fluid side.

Abstract: A valve plate subjected to a nitrocarburization heat treatment process for use in a hydraulic pump, wherein the hydraulic pump includes a sump having a rotatable cylinder block located therein.

Abstract: A valve assembly for use in regulating the flow of fluid between a first fluid side and a second fluid side of a hydraulic circuit. The assembly has an insert mounted in a hydraulic component having at least a portion of the hydraulic circuit formed therein, the insert also has a first end exposed to the first fluid side, a first end opening formed on the first end and a second end open to the second fluid side. The valve assembly additionally has a valve plug retained within the second end of the insert and a valve seat surface formed on the first end of the insert. The valve assembly also has a combination check valve and pressure relief valve located within the insert between the valve seat surface and the valve plug to selectively open and close the first opening.

Abstract: A combination check valve and pressure relief valve is provided for use in regulating the flow of fluid between a first fluid side and a second fluid side. The combination check valve and pressure relief valve includes a valve plug, a valve guide moveably positioned in relation to the valve plug, a valve stem engaged to the valve guide, a check compression spring attached to the valve stem and positioned between the valve guide and the valve plug, a valve seat carried by the valve stem, and a relief compression spring positioned between the valve seat and the valve guide. The valve guide is adapted to move the valve stem relative to the valve seat against the force of the relief compression spring to allow fluid to pass from the first fluid side to the second fluid side through a fluid flow passage formed between the valve stem and the valve seat.

Abstract: A hydrostatic unit comprising a surface coating on a running surface. A center section or valve plate for use in a hydrostatic transmission is improved through application of the surface coating on one or both of its pump running surface and motor running surface. The end cap for a hydrostatic pump is improved in a like manner.

Abstract: A method of configuring a valve comprised of a valve seat, a valve stem, a valve guide, and a relief compression spring. The method comprises calculating a compression force required to move the valve stem relative to the valve seat, using that calculated force to move the valve guide into a desired position, then crimping the valve guide to the valve stem at that desired position. The method also comprises attaching a check compression spring to the valve stem at a location inside the valve guide, installing the valve in a test stand to measure the actual pressure required to achieve the desired rate of fluid flow and forming the valve seat using metal injection molding.

Abstract: A combination check valve and pressure relief valve is provided for use in regulating the flow of fluid between a first fluid side and a second fluid side. The combination check valve and pressure relief valve includes a valve plug, a valve guide moveably positioned in relation to the valve plug, a valve stem engaged to the valve guide, a check compression spring attached to the valve stem and positioned between the valve guide and the valve plug, a valve seat carried by the valve stem, and a relief compression spring positioned between the valve seat and the valve guide. The valve guide is adapted to move the valve stem relative to the valve seat against the force of the relief compression spring to allow fluid to pass from the first fluid side to the second fluid side through a fluid flow passage formed between the valve stem and the valve seat.

Abstract: A combination check valve and pressure relief valve is provided for use in regulating the flow of fluid between a first fluid side and a second fluid side in a hydraulic circuit. The combination check valve and pressure relief valve includes a valve plug, a valve guide moveably positioned in relation to the valve plug, a valve stem engaged to the valve guide, a check compression spring attached to the valve stem and positioned between the valve guide and the valve plug, a valve seat carried by the valve stem, and a relief compression spring positioned between the valve seat and the valve guide.