Peter Elford


Peter Elford described this as a “stimulating” first project build with drawings and gunmetal castings from Southworth Engines.

“New to model engineering, this was my first experience of using a lathe and small mill/drill. It proved a challenging model to build, chosen because it incorporates many construction features of more complex steam engines and was considered to be a good ‘learning tool’.”

Southworth produces three sizes of vertical steam pumps in which layout is the same, having the steam cylinder at the top and the water at the bottom, all working on the same principle. In the steam chest there are two slide valves, the first one operated from the piston rod which passes steam to a shuttle. This shuttle has the second valve attached to it and controls the steam in and out of the cylinder. This is a reliable method of operating the pumps and is self-starting from any position. They can be run at a fairly high speed, or slowed down ‘till barely moving. They are all suitable for steam boats, locomotives and stationary steam plants. On the first sheet of the drawings there is an assembly with all parts itemized along with a parts list.   The other sheet or sheets shows details of all the parts to be made.

The 12 inch pump was designed for full size steam boats and similar applications. The water end is divided into two main castings, the cylinder and valve chamber. This makes for ease of machining, also the water ways are drilled which ensures correct position, size and no sand inclusions. The bosses are big enough to take ½ inch BSP fittings. The valve chamber top cover with the water outlet can be fitted, at the construction stage, either way. Also with the cover removed all four valves can be taken out for inspection.

The six inch pump (as built by Peter) is similar in principle. The water cylinder and valve chest are one piece. All castings are in gunmetal. The Southworth drawings show alternative water valves i.e. ball and the more efficient three-wing type.

A three inch pump is different from the other two. It does away with the pivoted valve operating arm and, in its place, milled cross ports have been employed.   The ram of the water cylinder is an extension of the steam piston rod. The other difference is that it is single acting and the two water valves are horizontal. Because of this the two three-wing valves are kept on their seats by springs.

The pump can also be used as an oil pump. -

the only weekly magazine for model engineers  Editor: David Carpenter