Patent ID: 6796392
Filing Date: 2004-09-28
Classification: B62D

Abstract:
A walk-behind, self-propelled working machine, comprising:a machine body; a drive source mounted on the machine body; a pair of driving wheels mounted on the machine body and rotationally driven by the drive source; a working tool mounted on the machine body and driven by the drive source; a continuously variable transmission interposed between the drive source and the pair of driving wheels; an operating handle extending from a rear end portion of the machine body; a grip mounted on the operating handle; an operation switching lever mounted on the operating handle in the vicinity of the grip for transmitting or interrupting a driving force outputted from the drive source to the working tool; a drive switching lever mounted on the handle independently from the operation switching lever and in the vicinity of the grip for undergoing pivotal movement for operating the continuously variable transmission to switch the pair of driving wheels from a halt condition to a high-speed advancement condition; and a variable speed adjustment mechanism for adjusting a rotational speed of the driving wheels, the variable speed adjustment mechanism having a disc rotatably mounted on the operating handle and having a slot disposed eccentrically relative to an axis of rotation of the disc, a speed adjusting rotary control member mounted on a side portion of the operating handle in the vicinity of the drive switching lever and connected to the disc for rotation therewith, a shift arm connected to the drive switching lever for undergoing pivotal movement therewith and connected to the disc for relative movement therewith in response to pivotal movement of the drive switching lever, and a positioning mechanism for positioning the disc at a preselected angular position relative to the shift arm and the drive switching lever by rotation of the speed adjusting rotary control member to adjust the rotational speed of the driving wheels.