Primary Clutch Operation - Toro Workman HDX Auto Service Manual

Primary Clutch Operation

The operation of the primary clutch is affected by engine
shaft speed. With the engine not turning, the CVT drive
belt rests low within the primary clutch sheaves as the
pressure of the clutch spring holds the sheaves apart. As
the engine increases in speed, the clutch weights at-
tached to the moveable sheave move outward as they
spin about the engine crankshaft. The outward move-
ment of the clutch weights presses against the clutch
rollers and overcomes spring pressure through the spi-
der assembly, which forces the moveable sheave closer
to the stationary sheave. This inward movement of the
sheave engages the drive belt to drive the secondary
clutch.
With increasing engine speed, the moveable sheave
continues to move inward, which forces the drive belt to
ride towards the outer diameter of the primary clutch
sheaves.
When engine speed is decreased, the clutch weights ex-
ert less force on the rollers and thus the spring. The
spring pressure overcomes the force of the clutch
weights and shifts the moveable sheave away from the
stationary sheave. The drive belt disengages from the
primary clutch sheaves at a point where the force of the
spring is greater than that of the clutch weights.
Speed Control System Operation
Toro's proprietary Speed Control insures precise ground
speed to engine speed critical for accurate application
rates with bed mounted topdressers and sprayers. The
speed range of the vehicle can easily be adjusted with
the speed range lever to limit the maximum−ground
speed of the vehicle. The speed range lever (Fig. 22) is
used to select one of four (4) work−speed ranges that
are used to limit maximum ground speed or a transport−
speed range that is used when the machine is moved
between job sites.
The speed limiter cover assembly is used on the Work-
man Auto vehicle to adjust the maximum opening of the
primary clutch moveable sheave. The speed limiter con-
trol uses a manually operated hydraulic cylinder to
change the location of the piston in the speed limiter cov-
er assembly. The piston location determines the maxi-
mum primary clutch opening.
Drive Train
1
2
3
1. Stationary sheave
2. Moveable sheave
3. Spider assembly
4. Speed limiter cover
1. Speed range lever
Page 4 − 6
4
7
Figure 4
5. Clutch weight (3)
6. Roller (3)
7. Spring
1
Figure 5
2. Speed range settings
Workman HDX Auto
5
6
2