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MMD > Archives > November 2009 > 2009.11.16 > 06Prev  Next

Suction Box in Modern Aeolian Player Piano
By John A. Tuttle

Hi All,  Typically, I don't like to disagree with other technicians,
and I hope to phrase this posting such that it sounds more like a
warning than a disagreement.

Recently, it was recommended that an after-market motor speed
controller be used in conjunction with a modern Aeolian suction box.
(I prefer to call it a vacuum pump.)  The rationale that was given had
to do with decreasing the noise level of the pump, which runs at full
speed all of the time, in order to control the volume of the music.

While I agree that decreasing the speed of the motor will decrease
the noise level, and the vacuum level and the volume of the music,
I feel it's important to point out something I mentioned in the web
page I created about the pump that Aeolian installed.

Aeolian purposely used unregulated vacuum to power the Auto-Reroll
device.  They could have more easily taken the vacuum from the reservoir
and avoided the need for the extra internal flap valve inside of the
vacuum pump.  So, one has to ask, "Why did they elect to complicate the

I have no way of knowing the answer for certain, but I do have many
hundreds of hours of experience with the modern Aeolian players.  In
fact, I've worked on over 500 of them in the tri-state area over the
past 37 years.  (The very first modern player I worked on at Freehold
Music Co, in Freehold, NJ was a modern Aeolian.  That was while I was
still in the Navy, working part-time as a player technician in 1972.)

One of the constant problems with the modern Aeolian players involves
the auto-reroll function.  In more instances than I care to remember,
the Reroll device simply lacked the power to shift completely from Play
to Reroll.  And in at least 90% of the cases, the main problem involved
the linkage.  While I don't have the time to go into all of the details,
the design is complicated and demands that the Reroll device overcome
the forces of three springs and the friction of four linkage guides.
Also, there are odd angular changes in the linkage which further
increase the amount of friction that the device must overcome.

To put it simply, unless everything in the linkage is working very
smoothly and with the least amount of friction possible, the device
lacks the power to complete the shift from Play to Reroll.  Aeolian
soon realized that part of the problem involved the Reroll Brake.
When the unit is shifted from Play to Reroll, the brake applies direct
pressure on the large gear in the transmission via a leaf-type spring
connected to the shift lever.  The added resistance of the spring
occurs about an 1/8" before the transmission finishes shifting into

The problem was so pervasive that QRS felt it was necessary to advise
owners to completely disable the "Reroll Friction Brake".  They did
this in their roll catalog, claiming that doing so would prevent the
rolls from curling or tearing during reroll.

As a side note, if what QRS said was true, then every reroll friction
brake in every player piano should be disabled.  However, they didn't
say that.  The picture they showed in their roll catalog is the one of
the transmission that's in the Aeolian Service Manual.  And, they
narrow the problem to "many of the new spinet players".

Personally, I struggled for years trying to make sense of what QRS
suggested.  Then when I started encountering repeated reroll problems,
I came to the conclusion that QRS just got tired of fielding complaints
that "their" rolls 'didn't reroll properly' on the 'new spinet players'.
And, they found that a quick fix to the problem was disabling the
friction brake.  I should also note that I never experienced the problem
that QRS claimed was caused by the friction brake, and none of my
customers ever mentioned the problem to me.  (All this makes me wonder
how many reroll friction brakes were needlessly disabled because of
what QRS advocated.)

Getting back to the subject at hand, as the years went by, the reroll
problem with Aeolian players only got worse.  That happened for two
main reasons.  One, the cheap metal that Aeolian used for the linkage
got corroded, and the corrosion caused increased friction at the four
linkage guides.  Two, the bend that was put into the linkage, to
trigger the cut-out device, which is turned on and off by a pallet
valve that uses a spring steel leaf to open and close the valve,
created an increase in friction as the metal corroded.  Suffice it to
say that the overall drag created by corrosion became so great that
quite often it was difficult to shift the Play-Reroll lever from Play
to Reroll by hand, let alone shift it with the Reroll device.

My point is simply this: considering the design of the linkage,
decreasing the vacuum level decreases the power to the Reroll device,
which under full vacuum usually struggles to do its job.

My advice, unless you're looking for trouble that could be hard to
explain to your customer, don't install a motor speed controller in
a modern Aeolian player.

Lastly, for reference purposes, I have put up a series of pictures
that show all of the Play-Reroll linkage in the modern Aeolian player.
It is located at: 

John A Tuttle
Brick, New Jersey, USA

(Message sent Tue 17 Nov 2009, 00:15:59 GMT, from time zone GMT-0500.)

Key Words in Subject:  Aeolian, Box, Modern, Piano, Player, Suction

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