Patent ID: 7234385

Claim:
A hydraulic drive apparatus, comprising a casing having a hydraulic pump mounted therein, the hydraulic pump including a movable control member for controlling the output of the pump; a rotatable shaft coupled to the control member and extending from the casing; a speed adjusting mechanism mounted to the casing and drivingly coupled to the rotatable shaft, the speed adjusting mechanism comprising: a return member mounted to the casing; a control arm engaged to the rotatable shaft and movable between forward and reverse positions to move the control member between forward and reverse positions, respectively; and a torsion spring operatively coupled to the return member and the control arm for biasing and returning the control arm to a neutral position after the control arm has been moved to at least one of the forward or reverse positions, wherein the return member includes at least one spring stop for preventing outward movement of at least one leg of the torsion spring when the control arm is rotated in a first direction while permitting inward movement of the at least one leg of the torsion spring when the control arm is rotated in a second direction opposite the first direction, and wherein the at least one spring stop is a slot in the return member through which the at least one leg of the torsion spring extends.