Worm Drive Transmission; Internally Clutched; Description - Toro 20330 - Low Wheel Walk Power Mower Service Manual

WORM DRIVE TRANSMISSION

GENERAL
There are two versions of the worm drive transmission.
The fi rst is a clutch type and is used on 21" front wheel
drive mowers. The second version is constant mesh and
is used on International 48cm rear wheel drive mowers.

INTERNALLY CLUTCHED

Description

This is a worm and helical gear transmission. The worm
shaft (input shaft) is driven by a belt from the engine
crankshaft. A spring which hooks into the tab on the
front of the transmission (where the roll pin is) and to
C D
F
1-2
B
E
G
the mower housing, pivots the transmission forward to
maintain tension on the belt.
The worm is in constant mesh with the helical gear. The
clutching action is provided by a sliding clutch jaw. A shift
fork moves the clutch jaw to engage and disengage the
transmission. When the clutch jaw engages the helical
gear, power is transferred from the clutch jaw to the
sleeve inside the clutch jaw. The sleeve is pinned to the
axle. The axle then begins to rotate (Fig. 001).
A. Belt
B. Spring
C. Helical Gear
D. Clutch Jaw
A
E. Shift Fork
F. Sleeve
G. Input Shaft
(worm shaft)
Fig 001
WPM Drive Systems Manual
fi g 1