Drive Clutch Operation; Driven Clutch Operation; Pvt Break-In (Drive Belt / Clutches); Maintenance / Inspection - Polaris 2012 RANGER RZR 570 INTL Service Manual

Drive Clutch Operation

Drive clutches primarily sense engine RPM. Th e two
major components which co ntrol its shifting function are
the shift weigh ts and the coil spr ing. When ever eng ine
RPM is in creased, ce ntrifugal for ce is cr eated, ca using
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 ou ter she ave moves inw ard an d co ntacts th e drive
belt. This motion pinches the drive belt between the spin-
ning shea ves and cause s it to ro tate, wh ich in tu rn
rotates the driven clutch.
At lower RPM, the drive belt rotates low in the drive clutch
sheaves. As engine R PM in creases, centrifugal force
causes the drive belt to be forced upward on drive clutch
sheaves.

Driven Clutch Operation

Driven clutches pr imarily sense to rque, ope ning and
closing according to the forces applied to it from the drive
belt and the transmission input shaft. If the torque resis-
tance at the transmission input shaft is gr eater 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 in to the sheaves of the driven clutch. Th is
action, which increases the driven clutch speed, is called
upshifting.
Should the throttle settin g re main th e sa me a nd 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 th e drive clutch. This action,
which d ecreases the dr iven clutch
backshifting.
In situations where loads vary (such as uphill and downhill)
and th rottle s ettings ar e co nstant, the drive and dr iven
clutches ar e con tinually shif ting to main tain o ptimum
engine RPM. At full thrott le a perfectly matched P VT
system should hold engine RPM at the peak of the power
curve. This RPM should be ma intained dur ing clu tch
upshift and backshift. In this respect, the PVT system is
similar to a power g overnor. Rath er than var y throttle
position, as a conventional gove rnor doe s, th e PVT
system ch anges e ngine lo ad r equirements by e ither
upshifting or backshifting.

PVT Break-In (Drive Belt / Clutches)

A proper break-in of the clutches and drive belt will ensure
a longer life and better performance. Break in the clutches
and drive belt by operating at slower speeds during the 10
hours as recommended (see Chapter 3 "Engine Break-In
Period" for break-in example). Pull only light loads. Avoid
aggressive acceleration and high speed operation during
the break-in period.

Maintenance / Inspection

Under normal use the PVT system will provide years of
trouble fr ee
maintenance is required to keep the system operating at
peak performance. The following list of items should be
inspected
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 an d Driv en Clutch But tons a nd Bush ings,
3. Sheave Faces. Clean and inspect for wear.
4. PVT Syst em Sealing. Re fer to
speed, is ca lled
9923523 - 2012 RANGER RZR 570 Service Manual
© Copyright 2011 Polaris Sales Inc.
operation. Pe riodic
and ma intained
Drive Clutch Shift Weights and Pins, Drive Clutch
Spider Rollers and Roller Pins, Drive and Driven
Clutch Springs.
illustration(s) on t h e following pages. The PVT syst e m
is air coole d by fins on the
sheave. T he fins create a lo w pr essure ar ea in th e
crankcase cast ing, drawing air int o the syst em
through an in take du ct. The ope ning for th is in take
duct is located at a high point on the vehicle (location
varies by mo del). T he in take du ct d raws fr esh a ir
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 an d also to prevent wa ter an d other
contaminants from ente ring the PVT a rea. This is
especially critical on units subjected to frequent water
forging.
CLUTCHING
inspection and
to e nsure maximu m
the ap propriate
drive clutch sta tionary
6.3
6