Importance

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Abstract

A steering and ground speed control mechanism of a vehicle equipped with a dual-path hydrostatic drive system includes a pivot plate fixed to a vertical pivot post at a location between and equidistant from a pair of locations respectively linked to a pair of pump displacement control arms of a pair of pumps respectively coupled for delivering fluid to right- and left-hand drive motors coupled to right- and left-hand ground wheels. A train of elements for transferring steering inputs from a steering wheel to the pivot plate includes a timed belt and sprocket set with one of the sprockets being fixed to the pivot post and the other mounted to a fixed post together with a quadrant-shaped steering rack for pivotal movement about the fixed post in concert with the rack. Pivoting the pivot plate in opposite directions from a centered position causes different displacements of the pumps and, hence, in the two drive motors being driven at different speeds. A train of elements for transferring speed inputs from a speed control lever to shift the pivot plate back and forth in a nearly straight path includes a push-pull cable coupled between the lever and an arm having the pivot post pivotally mounted in one end thereof, with the arm being mounted for pivoting about the fixed post exclusive of the rack and sprocket. A spring-applied, hydraulically released latch is provided for latching the steering wheel and speed control lever in their respective 'centered' and 'neutral' positions when hydraulic pressure is absent and a 'neutral' start switch is positioned for being activated for completing a vehicle starting circuit only when the steering wheel and speed control lever are in these positions.

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First Claim