With regard to changing of sprockets to control rewind speed, it is not
necessary.  If you really need to slow down the rewind speed, a restrictor
orifice installed in the hose fitting between the governor and the pump
will do a good job of controlling the rewind speed.  Since the air quan-
tity used during play is less than those used for rewind, the governor
will still work properly during play.  For anyone who desires an adjust-
able orifice, a small ball valve installed in the line will work fine.
Care must be taken to allow sufficient air for the governor control at
high tempo rates.  (We have used a drilled out wooden orifice
successfully.)

The orifice system greatly reduces tab tear-off when children are using a
pumper.  This is aimed at those of you with young children who have rewind
speed contests. ;-)

Changing of sprockets on wind motors is not advised unless you are having
problems maintaining tempo on extended play rolls.  The ratios of
leverage between drive and driven sprockets relates directly to the
amount of air going through the air motor.  As the paper builds up on the
takeup spool, the torque requirements of the air motor increase, but the
speed requirements decrease.

To some degree this is automatically compensated by the throttling valve
on the tempo governor.  As the torque requirements increase, the vacuum
inside the air motor will also increase as the motor tends to slow down.
Because of pressure loss between the air motor and the governor pressure
regulator, full vacuum would not be obtained at the air motor until the
air motor was physically halted.

Going to a larger sprocket on the air motor would change the factory
engineering balance between speeds, torque, and air flow.  The end result
of the change would be a substantial slow down of the roll as the paper
builds up on the takeup spool.  Installing a smaller drive sprocket would
increase the tempo on paper buildup.  If you are experiencing either the
speed up or slow down, then an experimental sprocket change would be in
order.  NOTE:  Preceding assumes that your air motor and governor are in
good operating condition!

A quick test of the air motor can be accomplished by removing the suction
line, capping fitting on air motor, and trying to turn drive sprocket in
reverse direction.  (This actually turns the air motor into a vacuum
pump.)  Any leakage in valves or pneumatics will immediately be evident
as you rotate the motor shaft 360 degrees.  A very tight air motor will
be extremely difficult, if not impossible, to rotate!  If rotation is
fairly easy and/or jumpy, you have leakage.

A quick test on the governor.  Remove the governor spring.  Only a very
minimum air motor speed should be obtained on play (approximately 0 to 10
feet per minute).  Any faster speed would indicate that the bellows cloth
is too stiff, throttling valve blocked open or leaking, or the governor
bypass valve is leaking.  When through with test, don't forget to put the
spring back!

Bob & Sonja Lemon
Lemon's Player Piano Service
Sacramento, CA