If Patrick Mullarky wishes, he is welcome to send the pump to me,
and I guarantee that he will get back a quiet pump, with original style
wood crankrods. I have used one now for 12-13 years on my test bench.
They are fine.

   I haven't run into a flimsy grasshopper pump yet, but perhaps there
was one.  My pump has these measurements: crankshaft-- 5/8"dia. Main
bearing posts are 2" x 1.5", maple, adjustable, with "oilers" inserted.
The crankrods are about 4" ctr-ctr. The crankrod bosses about 2" x
1.25" with a 1/4" steel pin. The large pulley is about 12" dia. and the
bellows are 6" wide.

   Any pump that has too much resistance through the flaps will always
be noisy, and increasing the width of the flaps exacerbates the
problem. If a pump is to pump quietly, it must require as little flap
motion as possible to exhaust as much air as necessary without tending
to inflate each closing bellows. At least that particular flap is the
outside flap and easy to get to. One of the faults I have found is,
flaps which are too heavy and too tightly sprung. It is better to use a
lightweight shoe leather and pneumatic cloth backing today to prevent
stretching. The original leather was industrial grade, meaning it was
pre-stretched and compacted. You cannot buy that anymore.

   Also, the covering material should be regular weight bellows cloth,
and not the lighter grades of treadle cloth such as the covering sold
by Schaff.

Craig B.