Deejay, by changing the ratio of the primary drive from the engine to the reel, without changing the ratio of the reel-to-drum drive, you retain exactly the same cutting geometry including cuts per metre. All that changes is the ground speed. Of course this is adjusted continually by the operator of an SB45, by varying the drum clutch engagement with the squeeze-handle. The Alroh apparently has a fixed in-or-out drum clutch, so the only way to fine-tune the ground speed is by changing the engine speed, or the ratio of the belt drive by replacing the crankshaft pulley. Diablo's machine seems to have had an oversized crankshaft pulley fitted: perhaps the previous tenant was a marathon runner in continuous training.
