Since yesterday I have made great progress and I solved some of the
problems with the help of my brother-in-law who is a smith and engine
repair man.

1) The "boing" sound was caused by the alignment between the disc
and the dogwheel, but front-to-back, not sideways as I had thought.
Because of the old wood in the cabinet the engine was leaning to far
forwards, and the dogwheel was too engaged with the holes in the disc.
By putting small wedges below the front of the engine and behind the
lower part of the "soundboard?" it now runs smoother and without the
"boing".

2) We think we have the governor figured out: there is a knob at the
top right in picture Polyphon Start-Stop button.JPG.  This knob can be
turned and adjusts the arm below (picture Polyphon Governor 2
Overview.JPG) and this in turn moves the arm with the jewel closer to
or farther away from the small groove at the end of the endless screw,
thus adjusting the speed of the engine (picture Polyphon Governor.JPG).

3) Progress with the start-stop: the actual "brake" is not the tab that
goes down into the small wheel.  But when the tab goes down in the
hole, the other end of the arm lifts up, and the attached wire (picture
Polyphon Governor 4 lifting wire.JPG) pulls another small arm up, and
a small protrusion catches the stiff wire that is mounted besides the
"windmill" in the governor (picture Polyphon Governor 3 Stop tab.JPG).
And this is the "brake".  When the "start-button" is pressed again the
governor is released and the engine starts again.

4) How to adjust the stop?  When the tab is lifted from the small
wheel, the wheel moves slightly clockwise.  When the spring wheel comes
around again, the tab won't fall into the hole and the engine keeps
running.  There is a small screw (bent at the bottom, picture Polyphon
Start-Stop 3 small screw.JPG) that is perhaps meant to push the wheel
back (counter-clockwise) so that the tabs can fall again?

Or is the wheel meant to turn more?  Is there something missing instead
of the screw?  Is this where you can adjust the engine to go 1 or 2
rounds before stopping (X1 and X2 mentioned by an earlier contributor)?
Why are there two holes in the small disc?

5) The speed?  Mme. Françoise Dussour asked in 2001.07.18 MMDigest of
July 2001 about the correct speed for a 24" Polyphon, but I can't find
an answer.  Is there anyone who knows this?

I am sorry if all this is "common knowledge"!

And a note to my previous message:  The captions on the two pictures
Start-Stop 1 and Start-Stop 2 are switched round.

Sincerely,
Henrik Ewald
Denmark
roedskaeg@hotmail.com.geentroep [delete ".geentroep" to reply]

 [ Polyphon Governor overview
 [ http://www.mmdigest.com/Attachments/15/11/05/151105_003153_Polyphon%20Governor%202%20Overview.JPG 

 [ Polyphon Governor lifting wire and arm
 [ http://www.mmdigest.com/Attachments/15/11/05/151105_003153_Polyphon%20Governor%204%20lifting%20wire.JPG 

 [ Polyphon Governor arm with small tab
 [ http://www.mmdigest.com/Attachments/15/11/05/151105_003153_Polyphon%20Governor%203%20Stop%20tab.JPG 

 [ Polyphon small adjustment screw
 [ http://www.mmdigest.com/Attachments/15/11/05/151105_003153_Polyphon%20Start-Stop%203%20small%20screw.JPG