I am recovering most of the control pneumatics for a WW2-period
Link Aviation Trainer.  The trainer sits on a gimbal bearing and can
rotate 360 degrees and tilt some in each direction, controlled by four
large accordion bellows.

The yaw axis rotation is driven with dual air-motors geared through a
large bull-wheel gear on a central shaft that drives a large round belt
to turn the trainer.  These motors look like standard roll-motors, with
five double-acting bellows.  Since there are two of motors, I would
call it a "V20" motor!

It is all very well made -- government specs, no doubt!  Each motor
bellows is more like an accordion bellows in that there is no "hinge"
edge, the hinging being handled by a block on a shaft between the two
bellows on one arm.  I will have to take pictures and post them for
y'all to see.  

This is going to be an interesting project!  It will be a little while,
as I have two customers ahead of this one.  The tilting bellows will be
pretty straightforward once I make a fixture for holding the ribs in
place for gluing.  They just will take quite a bit of cloth though, as
they're pretty large!

All this is powered by a Spencer "Turbo-Compressor" with 25 CFM at 40
oz.  Hmmm; this is terminology I'm not familiar with; I'll have to look
up the "40 oz."

More to come!  Hope y'all are interested -- if not, let me know, I can
stop! :)

David Dewey

 [ 40 ounces per square inch = 2.5 pounds per square inch = 69.2 inches
 [ water column.  -- Robbie