Over the years, quite a few people have tried to replicate this condensate pump of superior (but complicated!) design from the old US Navy steam cutters of the Great White Fleet era, for use in modern steam launches. At least one set of workable but somewhat simplified patterns is still floating around for the smaller Model G pump. The pump we attempted, at the request of a customer, is the larger pump used on the 50 hp model M engines in the 40 foot cutters. It is basically identical in design and detail to the smaller one, only with longer stroke and consequently longer pump body and base. To my knowledge, no one has reproduced this style pump in precisely the shape and design as the original blueprints. In every case I have seen, noticable shortcuts and design changes were introduced to make the job simpler to accomplish. We wanted ours to be as close the original Navy blueprints as possible. The following photo of our 1907 print shows the internal complexity of the pump body, with its three internal interlocking cored chambers.
A month and a half of full-time head-scratching and patternmaking produced a full set of sixteen separate patterns and seven core boxes. All patternwork was traditional, in mahogany and sugar pine, although the cores were made mostly in heat bonded resin-coated sand. Here are the patterns and principle cores laid out to be photographed:
Below, engineer and steam engine expert Keith Sternberg (on left) and I discuss the three interlocking pump body cores here assembled to be inserted in the mould:
We were apprehensive about the initial bronze heat due to the complexity of the pump body mould and cores, and thus the expense of a mistake; but we were gratified to have the very first one we poured turn out fine!
It was downhill from then on, with the other parts accumulated in subsequent heats and the machine work proceeding smoothly. In another five weeks of full time work, we had a finished pump:
Only very minor changes distinguish it from the original, and most of these were at the request of the customer. The flanges are threaded for normal 1 in. NPT pipe instead of the old brazed copper pipe. The valves have high-temp silicon O-rings inset into their faces to quieten their action rather than the metal-to-metal contact of the navy pumps. And stainless steel studs and nuts were used in most places, as well as a stainless steel piston rod. Also, the crosshead pin was increased in size from 7/16 in. to 1/2 in. for increased durability. A challenging but fun and rewarding project; and we at Marshall Machine and Engineering are very proud to have succesfully completed this commission. Anyone with an interest in these pumps and their construction is welcome to contact us here at Marshall Machine Works or Capt. Keith Sternberg with questions.