In deference to the Duo-Art "steamboat" pump, this smaller version
is commonly referred to as the "tugboat" pump.  I had one of these in
a 1912 Stroud, driven by a 1/8 HP Emerson motor, and no pump I ever
owned worked better.  In fact, I never had it out of the piano.

Interestingly, a small section of the plate casting was omitted to
provide additional clearance for the large pulley.  I've seen this
even on later pianos where the original pump is of a newer design,
making such a modification useless.

Jeffrey R. Wood