Don Teach wrote in 160305 MMDigest:

> Ampico had a brass band around the drum for a reason:
> aluminum grabs the brake band and brass does not.

The Ampico "B" brake drums are described on pages 46 and 47 of the
Ampico 1929 Service Manual: "The music roll brake is a fabric band
engaging a brake-drum on the music roll spindle and tensioned by means
of a small pneumatic fastened to the back board of the drawer. ... The
reroll brake is a snubber type band-brake mounted on the bass spindle
of the take-up spool."

The music roll brake drum (on the supply spool shaft) has a brass
band around it, probably to achieve smoother control of the hold-back
braking force.  Since the diameter of a Jumbo roll can vary from almost
3.5 inches down to about 0.83 inches, the holdback torque needed must
vary smoothly over a 4-to-1 range.

In the Ampico "B" drawer a needle valve is moved according to the
diameter of the supply spool in order to vary the hold-back torque
applied by a Prony brake.  The music roll brake drum consists of a tire
of 1/16-inch thick brass pressed onto a die-cast drum.  The resulting
assembly is 1.63 inch overall diameter with a face 0.850 inch wide on
which the fabric band of the Prony brake rides.

The photo of the link below shows an original music roll brake drum;
cracks are forming in the die-cast rim near the bottom of the picture.

Robbie Rhodes, MMD
Etiwanda, Calif.

 [ Ampico "B" music roll brake drum
 [ http://www.mmdigest.com/Attachments/16/03/06/160306_205130_Music_Roll_Brake_Drum.jpg