This roller chain transmits rotary motion from the drive sprocket to the metering and distribution components of the seed drill. It is a single-strand, 12B-1 pitch chain designed for the power-transmission path between the ground-driven wheel and the seed-metering shaft. A worn or stretched chain causes timing slip between the drive and the metering disc, leading to uneven seed spacing. The manufacturer machines the chain to the original pitch and roller diameter so that it engages the sprocket teeth without backlash, preserving the correct drive ratio. On installation, ensure the chain is tensioned to the manufacturer’s specification and that both sprockets are aligned in the same plane.