Service Manual

2-3
WPM Drive Systems Manual
WORMDRIVETRANSMISSION
When the shift arm is pulled to the rear by the shift
cable, the pin moves to the left side of the mower, then
to the rear. This moves the shift pin, the shift fork, and
the clutch jaw to the disengage position.
Note: Dirtpackedinthelatchplatecanprevent
disengagement.Thedustlteranddustcover
helppreventthisfailure.
When the shift cable is engaged, tension on the shift
arm is released. The spring on the shift rod applies
pressure to the rod, fork, and clutch jaw to engage the
transmission.
The shift rod has a roll pin protruding through the top
of the transmission. This pin goes through a latch plate
with an L shaped slot in it. The slot guides the pin in its
travel from engagement to disengagement. Above the
latch plate is a dust lter and a dust cover. The shift arm
on top of the transmission holds all these parts in place
(Fig. 003).
Lubrication
This transmission requires 90 wt. gear oil. A variable
weight such as 85w90 is acceptable as long as the
range includes 90 weight. The second part of the
requirement is an EP rating of GL 5 or higher.
The transmission has a ll/check plug in the front. With
the transmission level, ll until level with the hole. NOTE:
This is equal to about the center of the axle.
Unless the case is cracked, oil can not leak out. Even if
a seal fails, oil will leak out only to the bottom of the seal
on the axle.
If gear failure occurs, the resulting friction can cook the
oil down to a smear in the bottom of the case. This does
not indicate a lack of lubrication.
This type of transmission will last less than 30 minutes
with no lubrication. If a transmission lasts even a few
weeks in consumer use, it had lubrication to start.
TheShiftingProcess
The upper end of the clutch fork slides over a groove in
a spring loaded rod. This spring pushes the shift fork and
clutch jaw towards the engaged position (Fig. 002).
Fig002 3428-0150
A. Shift Rod B. Shift Fork
A
B
Fig003 3428-0165
A. Roll Pin E. Shift Arm
B. Latch Plate F. Screw
C. Dust Filter G. Shift Rod
D. Dust Cover
A
B
D
E
F
C
G