Driven Clutch Operation; Maintenance / Inspection - Polaris RZR 900 2017 Service Manual

DRIVEN CLUTCH OPERATION

Driven clutches primarily sense torque, opening and
closing according to the forces applied to it from the drive
belt and 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.
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
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.
9930588 R02 - 2017-2020 RZR 900 900/S 900/S4 1000/S 1000/S4 Service Manual
© Copyright Polaris Industries Inc.

MAINTENANCE / INSPECTION

Under normal use the PVT 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 PVT components. Refer
to the troubleshooting checklist at the end of this chapter
for more information.
1. Belt Inspection.
2. Drive and Driven Clutch Buttons and Bushings,
Drive Clutch Shift Weights and Pins, Drive Clutch
Spider Rollers and Roller Pins, Drive and Driven
Clutch Springs.
3. Sheave Faces. Clean and inspect for wear.
4. PVT System Sealing. Refer to the appropriate
illustration (s) on the following pages. The PVT
system is air cooled by fins on the drive and driven
clutch stationary sheaves. The fins create a low
pressure area in the crankcase casting, drawing air
into the system through an intake duct. The opening
for this intake duct is located at a high point on the
vehicle (location varies by model). The intake duct
draws fresh air through a vented cover. All
connecting air ducts (as well as the inner and outer
covers) must be properly sealed to ensure clean air
is being used for cooling the PVT system and also to
prevent water and other contaminants from entering
the PVT area. This is especially critical on units
subjected to frequent water forging.
PVT SYSTEM
6
6.5