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MMD > Archives > July 1999 > 1999.07.03 > 10Prev  Next

Air Motor Problem
By John A. Tuttle

Hi Robbie,  Most problems with otherwise well-functioning air motors
can be directly traced to contaminates; usually oil, grease or tar
(from cigarette, cigar or pipe smoke).  See:

The Pierce Piano Atlas says that Laffargue piano S/N 71703 was made
between 1919-1920.

According to the Player Piano Co. parts catalog, Laffargue used the
Standard, the Amphion or the Pratt-Read player action.  However, your
description of the air motor makes me think the action is an Amphion.

To the best of my knowledge, no air motors were built with leather
bushings, only wood (or metal) and felt.  The Amphion air motor has
these wooden grommets at the bearing points which are connected to
wires.  If oil was ever used as a lubricant, the grommets will need to
be aggressively agitated in lacquer thinner to leach out as much of the
oil as possible.  It would probably be best to change the felt bushing
at that point.

To find out if the above is actually the problem, dust the bearing
surfaces with powdered graphite.  If it gives temporary relief, a
thorough cleaning is indicated.

Next, I'd try cleaning the sliders and the block with lacquer thinner
to remove all the old graphite or buildup.  Then apply a sprinkling of
powered graphite.  Work it into the wood with your fingers and dust off
any excess.

If that doesn't cut it, remove the slider guides, run the motor and
check to insure that the sliders are moving straight up and down.
Adjust the connecting rods as required.

Lastly, if the sliders aren't centered directly over the vacuum supply
ports, bend the connecting wires carefully until everything runs flat,
smooth and even.  (If wooden flanges are used to connect the movable
board to the connecting rods, place shims of paper under the flange to
center the rod and slider.  This is the same technique used to center
action parts in the piano action.


John A. Tuttle

 [ Thanks for the information, John.  Now I can describe the situation
 [ to a local player tech and get an estimate to repair (including new
 [ felt bushings and recovering the air motor pneumatics, of course).
 [ -- Robbie

(Message sent Sat 3 Jul 1999, 12:25:44 GMT, from time zone GMT-0400.)

Key Words in Subject:  Air, Motor, Problem

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