This V-belt transmits power from the engine drive pulley to the variable-speed variator that controls the threshing drum speed. It sits between the fixed and movable sheaves of the variator, adjusting the drum RPM in response to load changes. A worn or glazed belt slips under load, causing a drop in drum speed that reduces threshing efficiency and increases grain loss. The belt is constructed by Gates to match the original cross-section and cord tension, which keeps the variator sheave clamping force within the design range. On reinstall, verify the belt tracks centered on both sheaves and adjust the variator stop bolts to the specified gap.