CAMERON STEAM PUMP BUILD
Part 12 by Jason Ballamy
Fabricating the yoke
CAMERON STEAM PUMP BUILD
Part 12 by Jason Ballamy
Fabricating the yoke
A lot of steam pumps have a quite distinctive ‘yoke’ which joins the pump ram to the piston rod but allows the crank to turn within it to keep the movement of the piston in line with that of the pump ram. I spent quite a while thinking of the best way to make this part and finally settled on a fabrication rather than cutting from solid.
The first job was to mark out the basic shape on some 1/16" steel sheet and drill a few holes so the two sides could be bolted together. They were then sawn to approx shape before mounting on the mill to drill a hole to give a nice radius where the two legs join.
A steel block of about 5/8 x 1" was drilled to suit the holes in the legs and a 3/8" x 40 thread cut in the middle into which the stainless steel pump ram will screw.
A quick clean up with a file and the thin lines of solder visible along the joint lines show that it all flowed quite nicely.
I then made up a threaded mandrel on the lathe and screwed the yoke onto it and gently centre drilled, drilled and reamed 1/4"" in the top block for the piston rod to fit, These two must be inline for a smooth running engine.
Back on the mill using a dummy piston rod in the vice and packing at the other end a hole was bored for the little end boss.
The top was then soldered, cleaned up and a raised boss turned around the piston rod socket.
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