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 > March 2018 > 2018.03.01 > 03Prev  Next

Rebuilding Pratt-Read 6-point Wind Motor
By John A. Tuttle

Hi All,  Over the past week or so, I've been communicating with Doug
Vensel about the 6-point air motor.  During the process of rebuilding
the motor, I collected all of the various measurements from Doug in an
attempt to more clearly understand what Jeff Davis said in his posting
(180223 MMDigest).  What I ended up creating in the eMachineShop CAD
program show how the motor moves (see attached video at link below).

While I don't understand the geometry well enough to explain it,
the other picture shows two circles where the radius is equal.  This
occurred when the bellows were open an equal amount.  Naturally, as
one bellows closes and the other one opens, the radius of the circles
and their orientation to each other changes.  As the bellows on one
side opens, the diameter of the circle decreases and the center of
rotation gets closer to the fulcrum.

Meanwhile, as the bellows on the other side is closing, the diameter
of the circle is increasing and the center of rotation is moving away
from the fulcrum.  When the boards of the bellows that's closing are
parallel to each other, the diameter of the circle is infinite and the
diameter of the circle on the other side is at its minimum.

Maybe an engineer in the group can explain all of this better...

John A Tuttle
Brick, New Jersey, USA

 [   Movement of the 6-point Pratt-Read air motor
 [   Two circles of rotation at the balance point
 [   One circle of rotation at the extreme

(Message sent Thu 1 Mar 2018, 13:27:23 GMT, from time zone GMT-0800.)

Key Words in Subject:  6-point, Motor, Pratt-Read, Rebuilding, Wind

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 1995-2024 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

Please Support Publication of the MMD with your Generous Donation

Pay via PayPal

No PayPal account required

Translate This Page