Sauer-danfoss Inc.

Richard L Otto

Alan W Johnson

Michael A Betz

Kerry G Geringer

Jeff L Herrin

Dennis M Greene

Philip W Katzer

Kenneth J Woodshank

A fixed displacement pump includes a housing having a cavity, an inlet, and an end cap with alignment portions therein. A cam ring pivotally associated within the cavity includes adjustment portions. The cam ring is aligned in a fixed position via a pin inserted through both a select adjustment portion and a corresponding alignment portion. The adjustment portion selected determines both rotational direction and displacement of the pump. The cam ring also includes recesses positioned adjacent the inlet to facilitate porting of fluid through the pump. A rotor mounted within the cam ring includes roller slots having groove segments. The groove segments are positioned in an arcuate arrangement about the rotor to facilitate porting of fluid through the pump. The rotor also includes undercut portions positioned between the roller slots in an arcuate arrangement on an outer edge of the rotor to facilitate porting of fluid through the pump.

Roller vane pump

A swashplate assist mechanism for dynamically varying swashplate moments in a multiple piston hydraulic unit includes a valve means disposed in the swashplate and defining a variable orifice for metering fluid from at least one of the pistons; and means for generating a control error signal to the valve means so as to adjust the size of the variable orifice based upon the control error signal. When fluid is metered from a leading piston to a trailing piston near one or more of the pressure transition zones, or when fluid is metered from a trailing piston to a leading piston near the opposite transition zones, the swashplate moments can be reduced.

Swashplate position assist mechanism

A reduced oil volume piston assembly for a hydrostatic unit includes a piston assembly having a piston body and a stem formed separately from the piston body. A cavity is formed in one end of the piston body. The stem includes an enlarged head and an elongated neck extending upwardly from the head. The neck lossely inserts into the cavity of the piston body so as to at least partially fill the cavity. The head is unattached to the piston body and cannot enter the cavity, but its shape allows fluid flow into the cavity around the stem. These components can be incorporated into the cylinder block assembly as separate components or the stems can be integrally cast with the cylinder block or attached thereto as a stem ring assembly.

Reduced oil volume piston assembly for a hydrostatic unit

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Marshalltown, IA, United States of America

Richard L Otto