Hello,  Andy Taylor wrote recently;

> Although belt-driven pumps (commonly referred to as 'box pumps')
> are somewhat better than turbine pumps against overheating,  extended
> plays still put an undue strain on the old motor and associated parts.
> As Karl Ellison pointed out in MMD, the Ampico player at the AMICA
> convention smelled "burned" after an hour of extended operation.

True, the old Ampico motors do get pretty hot.  I recently rebuilt a
badly knocking 1921 Ampico A motor.  The brass bushings were worn to
about .025 inch clearance between the shaft and the bushing.

The knock and consequently the badly worn bushings were due to a badly
balanced rotor from the factory that was probably originally manufac-
tured improperly.  A specialized machinist in my area has a dynamic
balancer and we had to drill holes in the laminates of the rotor to
correctly balance it.

After dynamically balancing the rotor and then testing on the bench,
under no load conditions, it did get too hot to touch.  The electric
motor rebuilding facility near me said that it was okay for it to get
that hot; the windings, insulation, and coatings can tolerate it.

This Ampico piano had the burning smell, too, when it ran for 30 or
more minutes continuously.   I found that the burning smell was coming
from years of oil that had been over lubricated and also someone put
grease in the oil wick reservoirs.  As Art Reblitz said, the oil gets
on the windings and the heat sizzles and cooks the oil and grease.

These brass bearings require very little oil.  Just enough in the wick
to slightly wet it.  Do not use grease.  If one is faced with the
burning smell, I recommend that the motor be taken to an electric motor
rebuilding shop that has the capability to steam-clean the inside
stator and rotor and re-coat it with the high temperature red stuff
that they use.  Reassemble and install new wicks and lubricate.  The
smell will cease and you can run the PowerRoll continuously.

It is very hard to find replacements for these old replacement
bushings, so a bearing distributor suggested that I install the newer
type porous bronze bushing that have the oil impregnated into the pores
of the bushings.  These type of bushings are used in most modern motors
today.

I installed these and the motor runs good and supposedly doesn't
need lubricating ever.  I just left the wicks out.  I reamed out the
bushings until there is about .001-inch clearance for the shaft and
an adequate oil bearing.

If one insists on replacing the bushings with the exact replacements,
there is one place that I have found so far in the USA that will make
them for you.  That is Wheeler Bearing in South Carolina.  They require
a drawing, though.

The old bushings are solid brass and have diagonal channels for the
oil to flow.  Wheeler can make bushings with the channels in them.
Be careful when removing the old bushings and installing the new.
If the diameter of the new bushing is too big, one can break the cast
iron motor housing when pressing in.

Please tell of any experience of motor rebuilding.  I'm still a little
concerned about these self lubricating bearings and how long the
lubricating properties of them last.

Bing Gibbs
Player Piano Forte
Cupertino, California
playerpiano@ccnet.com
408-253-1866