Reverse rotation is prevented through the use of Planetgear™ backstops on all reducer series. The ratchet mechanism engages at any frequency for any time span, thus providing indexing or positioning capabilities. The pawls disengage by centrifugal force assuring quiet operation. Our internally mounted backstops operate in conventional gear oil. Rexnord® Backstop Sub Assembly, For Use With: Planetgear™ PGSTK Series Size Mercury 7000 CCW Rotation Speed Reducer