Andy Taylor writes:

> You can often change the gear that drives the upper spool (in rewind
> only) to a gear that has more teeth, and then adding more links to the
> chain (change the gear ratio).  This will slow down the reroll without
> affecting the play tempo in any way whatsoever.  This will keep the
>  player from rewinding the roll so rapidly.
>
> I have read that if you install a larger gear on the wind motor, it
> will turn more slowly, using less suction.  This is true, but it
> increases the rewind speed also.  It also decreases the power of the
> motor.

I think Andy may have misspoken here.  Generally, one would replace the
sprocket on the air motor with one with fewer teeth.  This means the
motor turns further for the same rotation of the transmission input
shaft.  This would slow down both the forward and reverse drive and would
add power to the takeup during play.  Theoretically it would take more air
to do this but the amount would be quite small and would have an
inconsequential effect on the amount of available air.

I have tried this on my foot pumped Ampico with mixed success.  The piano
is very tight and will "coast" quite a few seconds when I stop pumping.
Nonetheless, when getting to the end of very large rolls, the motor has
insufficient power to keep pulling the paper over the tracker when the
takeup spool is getting really full.  I reduced the sprocket size to try
to increase the power and reset the governor in the 75 range to get the
proper play speed.  (I know they are not really linear but this works
well enough).

This provided an improvement but it will still stall near the end of fat
rolls.  (Of course if some's good, more's better and too much should be
about right.  Unfortunately, I can't find a one-tooth sprocket to try !)

The only way to keep the roll going is to relieve the tension on the
upper spool brake.  Then, there is not enough tension to keep the paper
reliably on the tracker on small rolls.  I went back and checked the air
motor itself regarding the valve timing, the angle and amount of closure
of the pneumatics etc., to no avail.

All of this was enough to influence me to use an electric motor drive on
the Ampico A grand when it was restored.  I would be interested to hear
anyone else's experiences with foot pumped Ampico (or electric) and
Amphion air motors.

Thanks for your indulgence.

Bob Conant