Cub Cadet 4 x 2 Big Country - Poly Bed & Steel Bed - Manual (Page 55)

4 X 2 Drive System - (Steel Bed)
51
4.13. At around 1,400 RPM the sheaves of the driving
pulley should begin to close on the belt.
See Figure 4.13.
4.14. There should be no significant power transmitted
through the belt at idle speed. See Figure 4.14.
Figure 4.13
Idle speed: driving pulley
sheaves are fully separated,
and belt is riding in the root
of the pulley
Belt
Sheaves fully spread apart
Figure 4.14
Belt held stationary
with light friction for
the purpose of
demonstration
only.
4.15. As the engine speed increases from idle speed
to roughly 3,000 RPM, the sheaves of the driving
(engine) pulley will close-down on the belt.
See Figure 4.15.
• In the first increments of travel (closing
sheaves), the driving pulley will begin to transmit
force through the belt.
• As the driving pulley increases speed, and the
sheaves are drawn closer together by centrifugal
force acting on weights, the belt is forced out-
ward. As the belt is forced away from the root of
the pulley, to the perimeter, the drive ratio
changes.
• At lower pulley speeds, a “power ratio” exists
between the driving pulley and the driven pulley.
As speed increases, the drive gradually shifts to
a “speed ratio”.
• As the driving pulley tightens the belt, it is drawn
deeper into the sheaves of the spring-loaded
driven pulley. This maintains constant tension
on the belt, and enhances the ratio change.
Figure 4.15
At 3,000 RPM: driving
pulley sheaves are fully
pulled-together, and the
belt is forced to the outer
circumference of
the pulley
Sheaves close together