FIG 12
We now come to the grease or oil cocks, which I have mentioned before. They can be bought ready finished at most model shops, but for those who like to make everything for themselves, this is the way to proceed. [Fig. 12] is a section showing interior oil chamber that allows the cylinder to be oiled without stopping the engine by turning off cock A and opening cock B, then filling with oil; then shutting B and opening A allows the oil to descend into the cylinder and lubricate the surface.
Now for the method. Chuck a piece of brass wire about a quarter of an inch in diameter in the lathe, and turn up to external shape; then turn out cup C and drill through from end to end with fine drill; then enlarge chamber D with small bent graver, and take out of lathe and drill through at right angles to previous hole at A and B with larger drill; then put plugs of brass wire in and fit them with emery and oil; rivet over one end, and the other turn up into a handle. Then turn them in straight line with the oil-cup, and drill through with the small drill again. Tap the end E, and screw into cylinder cover, when it is finished.
FIG 13
To keep the boiler full of water as the fire empties it by driving it off in steam, the usual thing is to use a force-pump worked by an eccentric on shaft; but, as the friction is excessive, it takes a great deal of power away from a model. It is best, therefore, to work it by a hand lever, and the pump may be screwed on to the side of boat, the suction A ([Fig. 13]) being led through the boat’s side and riveted over, and the supply B brazed into lower part of boiler. C is the lever, and D the plunger, which must be quite true, and turned up in the lathe; likewise the valves E and F and the stuffing-box tapped and drilled. It is best to work it up from a casting, and the outside smooth down with an old file. The projection G will then have to be drilled and the lever pivoted through, having first cut a slot at H to allow the lever to rise and fall.
I will now describe a method of making an injector, or machine for filling the boiler with water by the power of the steam alone, and not in connection with the engine.
The injector was an accidental discovery by a Mr. Gifford, and has now become a universal favourite on board both large and small craft, as it works splendidly without affecting the engine. So you can run the boiler up with water whilst the engine is at rest in harbour or otherwise. And another great advantage over pumps is that the steam, being mixed with the water, raises it in temperature to nearly boiling-point, and so is a great saving in fuel.
