In this episode of Ranch Hand Tips, Charlie will walk you through how to make some adjustments to your sickle mower. Sickle Mower Adjustment. Adjusting the Belt Tension and Replacing a belt on a sickle mower 3 point tractor implement. – Ranch Hand Tips In this video I’ll show you how to replace or simply adjust your tension on a Sperry New Holland 451 Sickle Mower. Sickle Mowers are often called reciprocating mowers, bar mowers, sickle-bar mowers, sicklebar mowers or finger-bar mowers. Follow our Rankin Ranch “Ranch Hand Tips” Videos for more information on adjusting, using, and maintaining a Sickle Mower.