This V-belt drives the cutterbar assembly on the parent combine. It transmits rotational force from the drive pulley to the knife-drive mechanism that powers the reciprocating blades. A worn or slack belt causes uneven cutting speed and can lead to material bunching at the header intake. The belt is manufactured to match the original profile and pitch length so that tension and pulley engagement are maintained without adjustment beyond standard take-up. On replacement, verify the belt rides flush in the pulley grooves and tension to the specification for the drive system.