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8.4
CVT TRANSMISSION
CVT OPERATION
CVT OPERATION OVERVIEW
The power of the engine is transferred to the wheels
through the following components: Starting Clutch, Drive
Clutch, Drive Belt, Driven Clutch, Transmission, Drive
shaft(s), and Rear Gearcase (and Front Gearcase on 4x4
models).
During the development of a Polaris 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.
The Continuously Variable Transmission (CVT) consists
of four major assemblies: 1) Starting Clutch; 2) Drive
Clutch; 3) Drive Belt; and 4) Driven Clutch.
STARTING CLUTCH OPERATION
The starting clutch is located on the left (CVT) side of the
engine crankshaft. It is an RPM sensitive clutch that
connects the engine crankshaft to the CVT System.
When engine RPM is below the factory determined
engagement speed of the vehicle, return springs on the
staring clutch shoes hold the shoes inward away from the
starter clutch hub.
When engine RPM is increased, centrifugal force causes
the shoes to overcome the return spring force and swing
outward. When the shoes contact the surface of the
starter clutch hub, the hub rotates at engine speed. This
causes the CVT drive clutch mounted on the shaft of the
staring clutch hub to rotate at the same RPM.
Refer to the ENGINE section for more information.
DRIVE CLUTCH OPERATION
The CVT drive clutch, mounted on the starting clutch hub
shaft, is also RPM sensitive. The drive clutch basic
components are the inner (fixed) sheave, the outer
(moveable) sheave, the rollers (weights) and the cover
plate.
The drive clutch begins to rotate when engine RPM
reaches engagement speed and the starter clutch
engages.
At low RPM, the drive belt is located at the bottom
(smallest diameter) of the drive clutch sheaves resulting
in a low “gear” ratio. As engine RPM increases,
centrifugal force moves the drive clutch shift rollers
outward in their respective tracks toward the outside of
the drive clutch. This forces the moveable sheave farther
inward toward the fixed sheave. The inward movement
of the sheave forces the drive belt farther upward in the
sheaves toward progressively higher “gear” ratios (larger
diameter).
DRIVEN CLUTCH OPERATION
The driven clutch is connected to the drive clutch via the
drive belt and is mounted on the main gearcase input
shaft. The CVT driven clutch consists of a fixed sheave,
a moveable sheave with roller tracks, rollers, and a
compression style return spring.
The driven clutch is primarily torque sensitive, reacting to
the forces of engine power and vehicle load to control the
upshift
and
downshift
of the CVT system.
Engine power is sensed by the driven clutch via the drive
belt. Vehicle loads are sensed by the driven clutch
through the main gearcase input shaft.
If forces on the drive belt (engine power) exceed the
forces on the transmission shaft (vehicle loads) the drive
clutch sheaves move inward and the belt upward, which
forces the sheaves of the driven clutch apart against
spring pressure. The drive belt moves
downward
into the
sheaves of the driven clutch to a smaller diameter (higher
“gear” ratio), increasing the speed of the driven clutch.
This process is called
upshifting
.
WARNING
All CVT maintenance or repairs should be performed
only by a certified Polaris Master Service Dealer (MSD)
technician who has received the proper training and un-
derstands the procedures outlined in this manual.
Be-
cause of the critical nature and precision balance
incorporated into the CVT components, it is abso-
lutely essential that no disassembly or repair be
made without factory authorized special tools and
service procedures.
Summary of Contents for 2006 HAWKEYE 2x4
Page 84: ...NOTES ENGINE 3 46 ...
Page 104: ...NOTES FUEL SYSTEM CARBURETION 4 20 ...
Page 111: ...5 7 BODY AND STEERING POD EXPLODED VIEW ...
Page 121: ...5 17 BODY AND STEERING ...
Page 122: ...5 18 BODY AND STEERING ...
Page 123: ...5 19 BODY AND STEERING ...
Page 124: ...NOTES BODY AND STEERING 5 20 ...
Page 152: ...7 10 FINAL DRIVE FRONT GEARCASE CENTRALIZED HILLIARD EXPLODED VIEW ...
Page 181: ...8 13 CVT TRANSMISSION TRANSMISSION 18 ft lbs 24 5 Nm ...
Page 186: ...NOTES CVT TRANSMISSION 8 18 ...
Page 210: ...9 24 ELECTRICAL STARTER MOTOR EXPLODED VIEW BRUSH LENGTH SERVICE LIMIT 5 16 8 MM ...
Page 216: ...NOTES ELECTRICAL 9 30 ...