hosted on condor3913
 Mechanical Music Digest  Archives
You Are Not Logged In Login/Get New Account
Please Log In. Accounts are free!
Logged In users are granted additional features including a more current version of the Archives and a simplified process for submitting articles.
Home Archives Calendar Gallery Store Links Info
MMD > Archives > July 2008 > 2008.07.28 > 08Prev  Next

Rebuilding Duo-Art Graduated Pneumatics
By John A. Tuttle

Hi All,  The "span" of any pneumatic is _not_ measured from the
inside edges of the pneumatic boards. Instead, it is measured from
the outside edges.  This was established many years ago to avoid any
confusion with regards to the correct span.

As a general rule, all striker pneumatics (in player pianos) have
a maximum span of 1-1/4".  There are a few exceptions, but even they
are not relevant to a well-operating striker pneumatic.

With all striker pneumatics and bellows that collapse to do their
respective job, the greatest amount of force that the bellows exerts
occurs at the moment the bellows starts to collapse.  From that point
on, the force it exerts decreases to zero -- when it's fully collapsed.

(Naturally, we're not speaking here about reservoir bellows that have
internal springs which keep them from collapsing.  However, the same
rule applies to exhauster bellows, which generate their greatest force
when the foot pedal is initially depressed, or from the moment that
the external flap valves are fully seated.)

To my understanding, the reason for graduating the length of the
strikers in some Duo-Art mechanisms was to compensate for the weight
of the push rod.  Naturally, the longer rods are heavier, and all other
things being the same, a slightly longer bellow with the same span will
exert a slightly greater amount of force.  However, I'm not educated in
physics.  So, I can offer no proof that my understanding is correct.

John A Tuttle 
Brick, New Jersey, USA

(Message sent Mon 28 Jul 2008, 12:57:55 GMT, from time zone GMT-0400.)

Key Words in Subject:  Duo-Art, Graduated, Pneumatics, Rebuilding

Home    Archives    Calendar    Gallery    Store    Links    Info   

Enter text below to search the MMD Website with Google

CONTACT FORM: Click HERE to write to the editor, or to post a message about Mechanical Musical Instruments to the MMD

Unless otherwise noted, all opinions are those of the individual authors and may not represent those of the editors. Compilation copyright 1995-2023 by Jody Kravitz.

Please read our Republication Policy before copying information from or creating links to this web site.

Click HERE to contact the webmaster regarding problems with the website.

Please support publication of the MMD by donating online

Pay via PayPal

No PayPal account required

Translate This Page