Wheel Pinion Clutch; Component Defi Nitions - Toro 20330 - Low Wheel Walk Power Mower Service Manual

Wheel Pinion Clutch

The wheel pinion clutch has a three-fold purpose. One,
when the transmission is engaged, it causes the pinions
to move with the output shaft and drives the wheels.
Two, it provides differential action to allow easy turning
and excellent maneuverability. Three it disengages the
wheel pinions from the output shaft when the operator
is not squeezing the handle. This allows the wheels
to turn backwards without turning the gears inside the
transmission and provides low pull back forces similar to
those on a hand-push version (Fig. 136).
Component Defi nitions
27. Output Shaft – turns when the operator squeezes
the handle to provide power to the wheels.
8. Pivot Arm Assembly – provides support for the
output shaft with a bushing and a needle bearing. It
can be rotated in the end cap to change height-of-
cut.
9. Washer Pivot Arm – fi ts in corresponding recesses
on the pivot arm to protect pivot arm from premature
wear.
WPM Drive Systems Manual
Fig 136 3428-0028
WHEEL PINION CLUTCH
10. Keyed Thrust Washer – internal tab fi ts in the
keyway on the output shaft. This washer rotates
with the output shaft and protects outboard clutch
components from wear.
11. Clip Ring – fi ts in a groove on the output shaft to
retain the pivot arm and spring arm. The tab at the
center of the clip is extended and fi ts in the keyway
of the output shaft to prevent rotation. If an E-clip
is substituted, premature failure of the wheel pinion
clutch system will result.
12. Friction Ring – fi ts in a circular groove in the pivot
arm and works with the clutch washer to actuate the
key. It does not rotate.
13. Clutch Washer – is affi xed to the output shaft by
means of the key so it turns with the output shaft.
It is also allowed to rotate slightly with respect to
the output shaft. This slight back and forth rotation
actuates the wheel pinion key. Friction between the
clutch washer and friction ring causes the clutch
washer to lag the output shaft slightly once it is
engaged. That slight rotation is all that is necessary
to raise the wheel pinion key and engage the pinion.
14. LH Rocking Key – causes the wheel pinion to turn
with the output shaft when up. Allows the wheel
pinion to "free-wheel" when down. Clutch washer
brings key up. Wheel pinion turning forward "wipes"
key down. There is a left-hand and right-hand key.
15. RH Rocking Key – causes the wheel pinion to turn
with the output shaft when up. Allows the wheel
pinion to "free-wheel" when down. Clutch washer
brings key up. Wheel pinion turning forward "wipes"
key down. There is a left-hand and right-hand key.
16. Pinion Gear – positively engages the wheel gear
at all times. Engagement with the output shaft is
controlled by the wheel pinion key. The wheel pinion
is a powdered metal part and is symmetrical so that
it can be put on either way and still function properly.
5-3