Patent ID: 8997902
Filing Date: 2015-04-07
Classification: B62D,Y10T

Abstract:
1. A mechanism of direction control for a differential speed steered agricultural machine comprising: right and left drive motors; right and left hydraulic drive pumps connected in tandem to and driven by an engine, each drive pump having a displacement control mechanism including a pintel arm rotatable between first and second positions, rotation of which changes hydraulic fluid flow rate from respective drive pumps to control speed and direction of respective drive motors; a control input shaft connected to the left and right pintel arms, the shaft rotatable about its longitudinal axis and translatable along its longitudinal axis, rotation of the shaft causing simultaneous rotation of the pintel arms in opposite directions, translation of the shaft causing simultaneous rotation of the pintel arms in the same direction; a steering drive motor connected to the control input shaft to rotate the shaft thereby managing relative displacement of the right and left hydraulic pumps; and a steering wheel connected to rotate a hydraulic steering valve to the right and left of a central position, the steering valve directing a varying volume of pressurized hydraulic fluid to the steering drive motor, the variation dependent upon the degree and direction of steering wheel rotation from the central position, thereby causing rotation of the control input shaft in proportion to the degree of rotation of the steering wheel, wherein the ratio of steering wheel rotation to steering drive motor rotation may be selectively varied.