Toro Groundsmaster 328-D, Service Manual

Page: 289 / 402

General Information
Over-Running Clutch Operation
A drive shaft connected to the front axle provides power
for the rear 4WD drive axle. The drive shaft tor the rear
a x l e i n c o r p o r a t e s a n
OVER-RUNNING (ROLLER)
CLUTCH THAT TRANSMITS POWER ONLY IN THE FOR-
WARD DIRECTION
(Fig. 4).
Front and rear axle gear ratios and tire sizes were
carefully selected so that during normal operation, the
REAR AXLE PINION SHAFT TURNS SLIGHTLY FASTER
THAN THE REAR AXLE DRIVE SHAFT
.
Any time the front wheels begin to slip (such as when
climbing a steep hill), the forward movement of the
traction unit slows. This causes the rear axle pinion
speed to slow down. As soon as the rear axle pinion is
turning the same speed as the drive shaft, the roller
clutch will engage and power will be transmitted from
the drive shaft to the rear wheels – four wheel drive
(Fig. 4).
When the traction unit is turning, the rear wheels swing
out in a larger arc and must travel faster than the front
wheels. In this condition, the rear wheels and axle pinion
shaft are turning faster than the drive shaft and the roller
clutch is disengaged (Fig. 5).
NOTE: The four wheel drive system may not operate
properly if the tires are replaced by different size tires,
or if proper tire pressure is not maintained.
49 RPM
50 RPM
49 RPM
Unlocked
Locked
49 RPM
Rear axle
drive shaft
Rear axle
pinion shaft
Figure 4
Figure 5
Groundsmaster
®
300 Series Page 10 - 3 General Information