The New Zealand Railways Magazine, Volume 8, Issue 8 (December 1, 1933)
A Hobby for the Young — Making a Sand Engine
How many young readers would like something in the nature of an engine to play with? Here is a simple one, which, if made large enough, will provide fun for two or three at a time. And it will be quite real, in its behaviour, as an engine. There is no fire, no water, nothing more than clean dry sand required to make the engine go.
There is nothing really difficult to make (it will work, even if made ever so crudely), but do take my advice and don't go about it in a desperate hurry. Take your time and make a good job of it, and you will be surprised how much it will be admired by your friends, and how much fun you will get out of it. This, I know, for I made one myself, when a boy, and spent hours with it.
Now for the construction. Most of the material required is wood (two or three boxes, candle-box size would suit admirably). A few pieces of strong tin, a straight piece of thick fencing wire (about a foot long) and, if possible, a wooden wheel about nine inches in diameter and about one inch thick. Round the edge of the wheel, saw cuts must be made (about one inch apart and a quarter inch deep). Cut and fit into these slots pieces of thick cardboard (one inch square), and the wheel will then have paddles all round it. Two round discs of cardboard (twelve inches in diameter) must now be tacked on to the wheel, one on each side, thus making a lot of boxes round the edge of the wheel. It is the weight of sand in these boxes on one side of the wheel that causes it to go round.
The piece of wire has now to be fitted through the centre of the wheel for the axle, and the more carefully this is done the better it will work.
Mount this wheel in one of the boxes so that the ends of the axle stick out each side, and whatever works you are ingenious enough to make can be fitted on to these ends. Round pieces of wood fixed on and fitted with crank pins, connecting rod, etc., or paddle wheels made of cardboard, make it look like a real engine.
On top of the box which holds the wheel is placed another box for dry sand. Cut in the bottom of this box two holes, in such position that sand running out of one hole will make the wheel revolve in one direction, and from the other hole in the reverse way, but make these holes only about three inches apart and no larger than a thimble. Then take one of the pieces of thick tin and secure one edge of it to the bottom of the box with a screw. Secure this in such a way that it not only covers both holes, but by moving the free end it uncovers them again. This will be the starting handle.
The other piece of tin has to be fitted in a similar manner, but its movement will be at right angles to the first piece. By moving this section one way it uncovers one hole, and moving it the other way the other hole is opened. Care must be taken to see that it cannot let sand out of both holes at the same time. This second piece of tin needs to be worked by the reverse lever. By means of the controls, sand stored in the top box can be allowed to fall into the wheel, working it fast or slow, and in either direction. Quite a reasonable amount of power is generated.
A third box placed underneath provides ample space for used sand to accumulate without touching the wheel, and occasionally this has to be raked out and transferred to the coal bunkers up above. If a hole is cut in one end of the top box, and fitted with a firehole door, this can be opened to rake the “fire” or to replenish it from the bunkers, and this is much more like attending to a boiler than tipping a box full of sand into it.
The arrangement described provides a most realistic boiler and engine to play with. If well made it can be used even inside the house. It is very reliable in working, clean and absolutely safe.