Patrick P Lacher

US Patent:

20130133319, May 30, 2013

Filed:

Mar 2, 2012

Appl. No.:

13/805759

Inventors:

Patrick P. Lacher - Bismarck ND, US
Daniel J. Krieger - Bismarck ND, US
Gunter G. Matt - Bismarck ND, US

Assignee:

CLARK EQUIPMENT COMPANY - West Fargo ND

International Classification:

F15B 13/00

US Classification:

60327, 60445

Abstract:

A drive system for propelling a power machine over a support surface is disclosed. The drive system includes a hydraulic pressure source and a drive assembly. The drive assembly has a hydraulic motor in fluid communication with the hydraulic pressure source that is switchable between first and second displacement arrangements. A shift valve receives pressurized fluid from the hydraulic pressure source and provides a shift signal to the hydraulic motor to selectively cause the displacement of the hydraulic motor to shift between the first and second displacement arrangements. A sensing device capable of generating a load signal indicative of a load condition provided by the drive assembly is also provided. An electronic controller provides a control signal to the shift valve to control the displacement of the hydraulic motor in response at least in part due to the load signal.