Service Manual

5-3

WPM Drive Systems Manual

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).

Fig115 3428-0196

A. Intermediate shaft C. Shift key

& gears D. Gear sleeve

B. Bevel gear E. Output shaft & gears

Fig116 3428-0058