The Steamboating Forum

Very, very nice.
Food for thought.
Thanks
Ian

Here a crank driven feed pump (Steam launch "Bell Bird" 1876).


The crank is at the outside excenter.

Dietrich

Thanks
Ian

So you have farms in the U.K., right? And those farmers spray their crops. And almost certainly they use some version of what we use here in the states which is an eccentrically driven piston pump. These are also used extensively in self service car washes which I suppose are common over there as well.

I have a single cylinder 3 x 4 engine and I have a Hypro brand pump driven right off of the end of the crankshaft. It never gives me a moment's trouble and has about a 20% or so excess capacity which is bypassed into the hot well through a float valve.

I love watching crosshead driven piston pumps run but only on other people's engines. Sort of like my reaction to square meters of brass.

If you go for a new pump it can get pricy (300 USD+) but there are used ones for much less and they are infinitely rebuildable.

Now that’s certaworth investigating.
Thanks Mike

I have made very reliable feed pumps from common brass pipe fittings with two common swing type check valves. The interior bore of brass pipe is so smooth that no further finishing is needed, and a piston machined from brass bar stock has worked well, with a couple thousanths of an inch clearence in the main pumping cylinder brass pipe. I use two common "O-rings" for piston to bore seal, about 1/8 x 1/8 grooves cut into the piston (about one inch diameter piston) for o-ring fit. Several years service so far, without any O-ring failures nor leakage.

The general "rule of thumb" for O-rings in dynamic pumping service is to provide a piston groove that results in the O-ring cross section standing proud enough to assure contact all around the cylinder bore, with 85% of the ring groove being rubber filled. More crowded grooves will rapidly wear the O-ring. Be sure to remove any sharp corners on the grooves, and be sure to provide a tapered entrance at the beginning of the cylinder to allow insertion of the piston without cutting the O-rings during assembly.

This type pump works well at low speed, either fitted with a hand lever, or driven from a crank at up to about 100 RPM. I would recommend either toothed belt or bicycle chain drive to a reduced speed lay shaft for engines running at much over 100 RPM.

Thanks
Ian

Oh man, Dampfspieler! This is really beautiful. You really can spiel with Dampf.

I follow the same path as fred. With those fittings you can get all over the globe, you can build one with almost no investment, cheap as they are. And so many different sizes make it easy like Lego