Aeon 350cc, Service Manual

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CVT SYSTEM
3-31
CVT SYSTEM OVERVIEW
Only a certified Aeon Service Dealer technician who
has received the proper training and understands the
procedures outlined in this manual should perform all
CVT maintenance or repairs. Because of the critical
nature and precision balance incorporated into the
CVT components, it is absolutely essential that no
disassembly or repair be made without factory
authorized special tools and service procedures.
The Continuously Variable Transmission (CVT) consists of
three major assemblies:
1) The Drive Clutch
2) The Driven Clutch
3) The Drive Belt.
The internal components of the drive clutch and driven clutch
control engagement (initial vehicle movement), clutch up shift
and backshift. During the development of an Aeon ATV, the
CVT system is matched first to the engine power curve; then to
average riding conditions and the vehicle’s intended usage.
Therefore, modifications or variations of components at
random are never recommended. Proper clutch setup and
careful inspection of existing components must be the primary
objective when troubleshooting and tuning.
CVT MAINTENANCE / INSPECTION
Under normal operation the CVT system will provide years of
trouble free operation. Periodic inspection and maintenance is
required to keep the system operating at peak performance.
The following list of items should be inspected and maintained
to ensure maximum performance and service life of CVT
components. See “CVT Overheating / Diagnosis” on page 3.4
for more information.
1. Drive clutch rollers and bushings. Driven clutch rollers,
pins, and spring.
2. Clutch sheave faces. Clean and inspect for wear.
3. CVT system sealing. The CVT system is air cooled by fins
on the drive clutch. The fins create a low-pressure area around
the drive clutch. The clutch cover must be sealed to ensure
water and other contaminants entering the CVT area.
DRIVE CLUTCH OPERATION
Drive clutch primarily sense engine RPM. The major
components, which controls shifting function, are the shift
centrifugal weights (rollers) inside the moveable sheave.
Whenever engine RPM is increased, centrifugal force is created, causing the
rollers to push against the cam plate and force the moveable sheave toward the
drive belt. This motion pinches the drive belt between the spinning sheaves
and causes it to rotate, which in turn rotates the driven clutch. If belt speed is
sufficient, centrifugal friction shoes on the driven clutch overcome their return
spring pressure and swing outward against the transmission drive hub, and the
vehicle (if in gear) begins to move. At lower RPM, the drive belt rotates low in
the drive clutch sheaves. As engine RPM increases, centrifugal force causes
the drive belt to be forced upward on drive clutch sheaves, changing the ratio
of the drive to driven clutch from low to high.
DRIVEN CLUTCH OPERATION
CVT driven clutches primarily sense torque, but also react to
RPM, applying and retracting the friction shoes according to
the forces applied to it from the drive belt, while at the same
time reacting to the torque at the transmission input shaft. If
the torque resistance at the transmission input shaft is greater
than the load from the drive belt, the drive belt is kept at the
outer diameter of the driven clutch sheaves (low ratio).
As engine RPM and horsepower increase, the load from the
drive belt increases, resulting in the belt rotating up toward the
outer diameter of the drive clutch sheaves and downward into
the sheaves of the driven clutch. This action, which increases
the driven clutch speed, is called up shifting.
Should the throttle setting remain the same and the vehicle is
subjected to a heavier load, the torque sensing driven clutch
will close, forcing the drive belt back up toward the outer
diameter of the driven clutch. This also forces the belt
downward into the sheaves of the drive clutch. This action,
which decreases the driven clutch speed, is called back
shifting.
In situations where loads vary and throttle settings are
constant, the drive and driven clutches are continually shifting
to maintain optimum engine RPM. At full throttle a perfectly
matched CVT system should hold engine RPM at the peak of
the power curve. This RPM should be maintained during
clutch up shift and backshift. In this respect, the CVT system is
similar to a power governor. Rather than vary throttle position,
as a conventional governor does, the CVT system changes
engine load requirements by either up shifting or back shifting.