2003 Polaris Sportsman 600 Owners Manual - Page 106

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 applied to the 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 this 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 temperature 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 104