Page 236 - Manual Oficina Polaris RZR 570 13-18

PVT SYSTEM

PVT SYSTEM OVERVIEW

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

5.4 9926813 R06 - 2013-2016 RZR 570 Service Manual
© Copyright Polaris Industries Inc.