Service Manual
SECTION
6
TRANSMISSION
CAUTION! Servicing the Power Shift Snowthrower will
require working with some of the moving
parts.
To
prevent accidental starting of the engine while
performing service, take the following precautions:
Rotate the ignition key to
off
and remove.
Pull the wire
off
the spark plug.
Make sure the wire does not accidentally touch
the spark plug.
CAUTION! The Power Shift Snowthrower has the
feature of being able to be stood on the front housing
for service and storage. Always drain the fuel from the
tank prior to such service taking the following
precautions:
Drain
it
outdoors and make sure the engine is cool.
Wipe up any gasoline that may have spilled.
Do not drain the gasoline near any open flame or
Do not smoke when handling gasoline.
spark.
Transmission Operation
The transmission used on the Power Shift Snowthrower
is similar in concept to that used in Toro Rear Drive Rear
Baggers although the Power Shift gearbox has
directional capability as well as speed reduction. Six
separate systems work together to transfer power from
the input pulley to the output sprocket.
Input
System: The input system is straight forward,
consisting of a large pulley, a hub, and a pinion gear.
The assembly is supported in the case by a
ball
bearing.
See Figure
73.
Bevel Gears: See Figure
74.
The bevel gears rotate
freely with respect to the intermediate shaft and the
gears on the intermediate shaft. They are driven in
opposite directions by the input pinion gear.
The reverse bevel gear is supported on the intermediate
shaft by a bushing because
it
freewheels while the
transmission is in forward. The forward bevel gear rides
on the first gear hub.
No
bushing is used on the forward
bevel gear because it rotates on the hub only when the
transmission is in reverse.
The sliding jaw clutch is coupled to the fixed gear cluster.
It
is free to slide back and forth between the two bevel
gears. The direction of rotation of
the
fixed gear cluster
is determined by which bevel gear the sliding jaw clutch
engages.
Figure
73
NOTE: The jaw clutch has no intermediate position.
It
should always
be
completely engaged with one
of
the
bevel gears.
Figure
74
Fixed Gear Cluster: The fixed gear cluster and the
sliding jaw clutch rotate as an assembly on the
intermediate shaft. See Figure
75.
Selectable Gear Cluster: The selectable gear cluster
consists of four independent gears, two sleeves and the
shift mechanism.
See
Figure
76.
The sleeves rotate
freely on the output shaft and each is supported by a
bushing.
NOTE: The sleeve closest to the sprocket
is
also the first
gear in the speed reduction system.
Power Shift Snowthrowers
63
Transmission