Rodney E Williams

US Patent:

41857135, Jan 29, 1980

Filed:

Feb 13, 1978

Appl. No.:

5/877441

Inventors:

Rodney B. Williams - Higley AZ
Jerry A. Taylor - Dixon CA

Assignee:

Dixon "Y" Machine, Incorporated - Dixon CA

International Classification:

B60K 1734

US Classification:

180242

Abstract:

A hydrostatic drive system for a four wheel drive vehicle such as a field harvesting machine which must accurately track the planting rows, includes an engine, a pump and individual hydraulic wheel motors connected to the pump and coupled to the wheels through a manually set free wheeling clutch. The motors are in series connection at each side of the vehicle, with the pairs of series connected motors on opposite sides of the vehicle in parallel connection with the pump. When the traction of a wheel on one side is reduced or lost, both wheels on that side continue to rotate at the same speed. Under these conditions, the driving wheel motor on the aforesaid side of the vehicle will provide increased torque output to compensate for the reduced driving power of the slipping wheel. For road travel between harvesting fields, the wheels on the right side of the vehicle are mechanically declutched from their respective motors, and valves are closed to close off the hydraulic lines to the right side motors which routes all of the hydraulic fluid from the pump to the motors on the left side of the vehicle, and hence the ground speed of the vehicle in two wheel drive is approximately double the harvesting speed in four wheel drive for a given output of the hydraulic pump which drives the motors.