Polaris Ranger 500 2x4 2007, Руководство по обслуживанию, Страница: 181 / 345

6.3
CLUTCHING
6
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 trans-
mission 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.
Maintenance / Inspection
Under normal operation 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 Tension, Drive to Driven Clutch Offset, Belt
Width.
See these sections later in chapter for each model.
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.
See these sections later in chapter.
3. Sheave Faces. Clean and inspect for wear.
4. PVT System Sealing. Refer to appropriate illustration on
the following pages. The PVT system is air cooled by fins
on the drive clutch stationary sheave. 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.