Toro 20330 Service Manual - Page 67

THREE SPEED TRANSMISSION OPERATION Input System: Power is transferred from the engine to the transmission by a belt. The self-propel pulley at the engine is keyed to the crankshaft. The pulley on top of the transmission is supported by a ball bearing and drives a pinion gear inside the transmission. Tensioning of the belt is accomplished by pivoting the transmission. When the operator squeezes the control bar toward the handle, a control cable tilts the transmission backward and tensions the belt. When the control bar is released, gravity pivots the transmission forward to loosen the belt. Belt guides at the engine pulley and atop the transmission ensure disengagement by forcing the belt to loop around the engine pulley (Fig. 115). Speed Reduction System: Speed reduction is accomplished by two sets of gears - one set on the intermediate shaft and the other set on the output shaft. The gears on the intermediate shaft are powdered metal and ride on a hexagonal shaft supported on each end by oil impregnated bushings. These gears are driven by the pinion at the bottom of the input shaft. The driven bevel gear turns the shaft so that all three gears on the intermediate shaft have the same rotational velocity (Fig. 116). AB E C Fig 115 D Fig 116 3428-0058 A. Intermediate shaft & gears B. Bevel gear C. Shift key D. Gear sleeve E. Output shaft & gears 3428-0196 WPM Drive Systems Manual 4-3