Polaris Sportsman S User Manual download pdf (Page 106)

104

MAINTENANCE AND LUBRICATION

PVT System

The basic operation of the Polaris PVT system is dependent on engine

speed and vehicle torque requirements. As engine speed increases, the

force exerted on the movable drive sheave by the flyweights also

increases. This, in turn, increases the amount of pinch appliedtothe

drive belt. Similarly, if the engine speed decreases, the amount of

centrifugal force decreases, reducing the amount of belt pinch.

On Polaris ATVs, the approximate gear ratio difference between high

and low range is 1:2.25. This difference in gearing affects the operation

of the PVT, especially at speeds less than 7 MPH (11 KPH), due to the

system’s dependence on engine speed.

For example, when operating at a ground speed of 3 MPH (5 KPH) in

low range, the engine speed would be around 3000 RPM. This is well

above the engagement speed of 1200 - 1400 RPM. However, in high

range at 3 MPH (5 KPH), the engine would be running at only 1500

RPM. Whenever operating t his close to the engagement speed, the

engine may be running at a speed too low to provide the pinch needed

to prevent belt slip. Belt slip is responsible for creating the excessive

heat that destroys belts and causes outer clutch covers to fail.

By switching to low range while operating at low ground speeds, the

air t emperature in the clutch cover is reduced by almost 160 degrees.

Reducing the temperature inside the clutch cover extends the life of the

PVT components (belt, cover, etc.).

When To Use Low Range vs. High Range

Following is a guideline for when to use low range and high range.

Low Range

S When basic operation is at speeds less than 7 MPH (11 KPH)

S For heavy pulling

S When operating in rough terrain (swamps, mountains, etc.) at low

ground speeds

High Range

S When basic operation is at speeds greater than 7 MPH (11 KPH)

S When operating at high ground speeds

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Polaris Sportsman S User Manual Page 106