Abstract: A self-propelled, walk-behind traction vehicle includes a power source, a pair of drive wheels and an improved operator-manipulated drive control mechanism for selectively coupling the drive wheels to the power source in a manner that allows the operator to control propulsion and steering of the vehicles. The drive control mechanism includes a friction drive unit having a pair of reversible, variable speed transmissions associated with respective ones of the drive wheels for selectively coupling the drive wheels to the power source. The control mechanism further includes a pair of independently swingable control handles configured to be gripped by the operator and operably coupled to respective ones of the transmissions so that the speed and direction of rotation of each of the drive wheels is controlled by swinging a respective one of the handles.

Abstract: An automatic tensioner to be used with a drive train of a self-propelled mower for drivingly connecting a ground wheel to the mower transmission, wherein the tensioner includes tensioning mechanism, which may be constructed as a spring biased idler arm having an idler member rotatably mounted thereon, to apply a tensioning force against the flexible element of the drive. The tensioner further includes an anti-slackening assembly having an elongated takeup rod being pivotally coupled with the idler arm at one end thereof so that the takeup rod moves generally with the idler arm, as the arm moves in a tensioning direction and opposed slackening direction. The anti-slackening assembly also includes a swingable control tab having an aperture receiving the other end of the takeup rod.