[ I asked Richard about the design of the steamboat pump.  -- Robbie

The early Aeolian Company "Duo-Art Steamboat Pump" had three pairs
of bellows which were moved by a camshaft instead of a crankshaft.
Here is a picture, copied from an eBay entry, where someone was selling
one.  A coil spring connects the pair of bellows on each side of an
eccentric cam.  The spring is strong enough to keep the rollers in
contact with the eccentric cams at all times.

The Duo-Art steamboat pump has the reputation of being the quietest
ever devised, since there are no connecting-rod bearings to loosen and
knock.  The stroke is comparatively short, compared with other designs,
but it can go quite fast without noise.  The wooden rollers are covered
with leather, for even more noise reduction.  See
http://mmd.foxtail.com/Pictures/tuttle02.html

Although this was a fine design, and many collectors prize it, it was
so big and thick that it was soon replaced.  After that, they briefly
went to a similar arrangement with four bellows and short connecting
rods instead of eccentrics.  You can see one on Sam Harris' website:
http://www.geocities.com/Heartland/Ranch/9374/stroud/page09.html

By the 1920s Duo-Art had gone to the standard box pump, just like
Ampico.

Best regards,

Richard Vance

 [ See the photo at http://mmd.foxtail.com/Pictures/  -- Robbie