Didn't some of those very old shuttle machines have, instead of a crank, a knob attachment that worked along the lines of a steering wheel spinner? I seem to remember that getting discussed on TreadleOn back in 1998-1999 or so.
It could be left in place when the machine was in a treadle for a little extra oomph when needed for heavy fabrics. Or, used in lieu of a bolt-on crank on the machines that don't have a boss.
Whatever it was, it attached directly to the balance wheel, is what I recall.
Last edited by MadCow333; 05-04-2013 at 11:34 AM.