James G Whitaker

US Patent:

6837047, Jan 4, 2005

Filed:

Jun 10, 2003

Appl. No.:

10/457936

Inventors:

Xingen Dong - Greeneville TN, US
James S. Whitaker - Greeneville TN, US

Assignee:

Parker-Hannifin Corporation - Cleveland OH

International Classification:

F16D 3102

US Classification:

60464, 13711806, 137114

Abstract:

A hydraulic valve assembly, for use in a hydrostatic transmission, for controlling fluid transfer between a first, a second and a third line, wherein two of the lines define first and second pressure lines, within a closed-loop circuit. The valve assembly comprises: a valve body having ports in communication with the three lines; a spool bore; a valve spool, adapted for sealing reciprocation within the spool bore, having a first and second end portion, a connecting portion, and a first and second bypass orifice within the valve spool; and dampers for centering the valve spool. This spool is movable from a neutral position occurring when the fluid pressure forces in the first and second pressure lines are substantially similar, to a first or a second position occurring when the fluid pressure force in the first pressure line is greater or less than that in the second pressure line, respectively. The bypass orifices are enabled in the neutral position, but are substantially disabled in the first and second positions. A hydraulic system utilizing the valve assembly and a method for increasing the width of the dead band of the hydrostatic transmission in a neutral mode of operation are also set forth.

US Patent:

7430860, Oct 7, 2008

Filed:

Sep 28, 2005

Appl. No.:

11/237144

Inventors:

James Whitaker - Greeneville TN, US
Xingen Dong - Greeneville TN, US

Assignee:

Parker-Hannifin Corporation - Cleveland OH

International Classification:

F16D 31/02

US Classification:

60464, 60488

Abstract:

Improvement in a hydrostatic valve assembly for use in a hydrostatic transmission, for controlling fluid transfer between a first, second and third line, wherein two of the lines define first and second pressure lines within a closed loop circuit. The valve assembly comprises a valve body having ports in communication with the three lines; a spool bore and valve spool reciprocating therewithin, having first and second end portions joined by a connecting portion, and first and second bypass orifices within the valve spool; and dampers for centering the valve spool in a neutral position. The bypass orifices utilize increased cross-sectional areas that permit the passage of substantially the full flow of the charge pump, without using a charge pump relief valve, at a low pressure drop. A hydraulic system utilizing this valve assembly and a method for increasing the transmission efficiency, in the neutral mode, are also set forth.

US Patent:

20040187491, Sep 30, 2004

Filed:

Mar 24, 2004

Appl. No.:

10/807602

Inventors:

James Whitaker - Greeneville TN, US
Xingen Dong - Greeneville TN, US

International Classification:

F16D031/02

US Classification:

060/476000

Abstract:

A hydraulic pump for a closed-loop hydrostatic transmission circuit having an integrated shuttle valve for diverting hot fluid from the hydrostatic transmission circuit to a reservoir. The circuit operatively interconnects the hydraulic pump and a motor and includes a first line connecting a first port within the hydraulic pump to a first port within the motor and a second line connecting a second port within the hydraulic pump to a second port within the motor.