Years ago I bought this odd but beautiful air compressor and have never seen its like - what can anybody tell me about it?
Its fundamental design is to me unique. There’s a piston and connecting rod and crank and cylinder. But the piston rocks inside the cylinder as it travels, there being no pivot between piston and connecting rod, and no pivoting action for the cylinder itself. The cylinder axis does not intersect the crankshaft axis. Instead, the cylinder axis is roughly tangental to the connecting rod bearing path on the crankshaft, during the pumping stroke. During this stroke the piston seals against the cylinder walls. The return stroke causes the piston to rock considerably away from filling the cylinder, so that there are gaps on either side of the piston ring, and this is the valve action that lets it draw in more air for the next stroke. There is a considerable bend in the middle of the connecting rod to allow for this without the rod striking the end of the cylinder opening. The piston has a narrow band of contact with the cylinder, at its ring, which is stout leather and a bit pliable to create a robust seal during this not perfectly straight compression stroke.
This whole device has a pretty consistent construction theme - all the big parts are castings done in the same style, and I think they’re die cast zinc, heavier and bluer than cast aluminum. The crank is a flywheel with fan blades and counterweight cast in. The shaft on which the flywheel turns, the connecting rod bearing itself, and the fasteners are all stainless. It stands about 8" high at the highest. There is a head casting housing one check valve for the output. The cylinder has ten deep fins on approximately 1/4" centers. The shaft is flatted and the base is for the pump only without provision for a motor.
The only markings I see are a capital “P” inside a tall diamond outline, in two locations, and something faint that might say “Patent”. I probably bought it 20 or so years ago at a garage sale.
This is embarrassing, but I have never gotten around to learning how to post pictures online and setting up an account or whatever is needed to do it. What’s the easiest way?
Imgur: The magic of the Internet is a frontal view. The finned cylinder top is the highest point, at 9 inches. The crank is positioned midway through the compression stroke.
Imgur: The magic of the Internet is looking up from in front, and the crank is positioned midway through the return stroke. Note the extreme angle of the connecting rod.
Imgur: The magic of the Internet shows the head, with its single outlet, which measures to be 1/8" NPT. I suspect the large space in the head is supposed to act as a bit of a reservoir to damp pulsation.
Imgur: The magic of the Internet is the other side, not very interesting. Though the connecting rod has a ball bearing, the crankshaft itself runs in ordinary bushings with a hole for oiling. I am not sure the fasteners are original, now that I think of it, but they’re stainless steel.
Imgur: The magic of the Internet shows the trademark, a capital “P” enclosed in a diamond outline. Note behind that the counterweight area in the flywheel crank shows what looks sort of like a weld, but I am sure it was cast this way, like somebody took a small grinder to corners in the die itself.
Imgur: The magic of the Internet shows the piston near the bottom of the return stroke, during which it is cocked. Near photo bottom you can see the gap between the piston and the cylinder wall. The brown crescent is the stout leather piston ring. The nut with nylon insert is for compressing the leather ring just so; again, I do not remember for sure whether I might have replaced the fastener, so I am not sure whether the nylon insert is part of the original equipment.
Probably belt driven off a lathe or sewing machine to keep work area clear. Nothing interesting about the piston/crank/ring setup…the DeVilbiss I’m working on has the same setup with a rubber seal.