An outdoor power equipment unit such as, e.g., a walk-behind lawnmower including a frame, a power head, and a hydrostatic transmission, wherein the hydrostatic transmission includes a drive gear configured to rotate about a first axis. The unit also includes a pair of rear drive wheels coupled at respective ends of a rear drive axle, wherein the rear drive axle is operably coupled to a driven gear. The pair of rear drive wheels, the rear drive axle, and the driven gear are configured to rotate about a second axis. A drive chain is operably coupled to both the drive gear and the driven gear. Furthermore, a wheel height adjustment mechanism is provided, wherein the wheel height adjustment mechanism includes a first bell crank pivotally coupled to the frame about the first axis, with a first end of the first bell crank being coupled to the rear drive axle. A control assembly for controlling the speed and direction of the outdoor power equipment unit is also disclosed.
