Page 255 - Manual Oficina Polaris RS1 2018 e 2019

PVT SYSTEM

PVT SYSTEM OVERVIEW

GENERAL OPERATION DRIVEN CLUTCH OPERATION
Driven clutches primarily sense torque, opening and
WARNING closing according to the forces applied to it from the drive
belt and the transmission input shaft. If the torque
All PVT maintenance or repairs should be performed by
a certified Polaris Master Service Dealer (MSD) resistance at the transmission input shaft is greater than
technician who has received the proper training and the load from the drive belt, the drive belt is kept at the
understands the procedures outlined in this manual. outer diameter of the driven clutch sheaves.
Because of the critical nature and precision As engine RPM and horsepower increase, the load from
balance incorporated into the PVT components, it is the drive belt increases, resulting in the belt rotating up
absolutely essential that no disassembly or repair toward the outer diameter of the drive clutch sheaves
be made without factory authorized special tools and downward into the sheaves of the driven clutch. This
and service procedures. action, which increases the driven clutch speed, is called
upshifting.
The Polaris Variable Transmission (PVT) consists of Should the throttle setting remain the same and the
three major assemblies: vehicle is subjected to a heavier load, the drive belt
1) The Drive Clutch rotates back up toward the outer diameter of the driven
clutch and downward into the sheaves of the drive clutch.
2) The Driven Clutch This action, which decreases the driven clutch speed, is 5
3) The Drive Belt called backshifting.
The internal components of the drive clutch and driven In situations where loads vary (such as uphill and
clutch control engagement (initial vehicle movement), downhill) and throttle settings are constant, the drive and
clutch upshift and backshift. During the development of driven clutches are continually shifting to maintain
the Polaris vehicle, the PVTsystem is matched first to the optimum engine RPM. At full throttle a perfectly matched
engine power curve; then to average riding conditions PVT system should hold engine RPM at the peak of the
and the vehicle’s intended usage. Therefore, power curve. This RPM should be maintained during
modifications or variations of components at random are clutch upshift and backshift. In this respect, the PVT
never recommended. Proper clutch setup and careful system is similar to a power governor. Rather than vary
inspection of existing components must be the primary throttle position, as a conventional governor does, the
objective when troubleshooting and tuning. PVT system changes engine load requirements by either
upshifting or backshifting.
DRIVE CLUTCH OPERATION
Drive clutches primarily sense engine RPM. The two
major components which control its shifting function are
the shift weights and the coil spring. Whenever engine
RPM is increased, centrifugal force is created, causing
the shift weights to push against rollers on the moveable
sheave, which is held open by coil spring preload. When
this force becomes higher than the preload in the spring,
the outer sheave moves inward and contacts 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.
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.

9928689 - 2018 RZR RS1 Service Manual 5.3
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