This conversion came about when a friend donated the chassis from a Wilesco Fire Engine and also provided inspiration in the form of a couple of photos of "dog cart" style cars. What happened then is documented in this blog.
The burner is a Bix ceramic butane burner. It's probably a bit larger than is necessary but better too large than too small. The gas tank with it's own regulator is mounted under the rear seat. The boiler is one from a Wilesco D52 marine engine and is 45mm diameter x 108mm long. It has a circular water sight glass on one end. Other fittings consist of a whistle, safety valve, filler plug and steam feed pipe. The steam pipe goes under the rear seat to a steam regulator valve situated next to the gas regulator. Also under the seat is an in-line oiler.
From here, the feed pipe goes to the single cylinder double acting "piston" valve engine mounted under the chassis. This engine also came from the D52 with it's sub-chassis cut down to fit. The cylinder is 13mm bore x 16mm stroke. Reversing is by a slip-eccentric. Drive is taken from a pulley on the crankshaft, via a short spring type drive band, to a larger pulley on an intermediate shaft. On this shaft is a small sprocket from which a chain is connected to a larger sprocket on one of the rear wheels. This arrangement provides a two stage speed reduction.
The steering wheel is on the top of a column passing through the floor of the chassis to a pair of Meccano gears, which not only gear down but also reverse the direction as required. From here, a chain drive goes to a large gear wheel between the front half-axles. This gear wheel happens to have a pitch almost equal to half that of the chain, so that it can work as a sprocket. (In the original, the gear was driven directly by a small pinion on the end of the steering column, which was much further forward than it is now.) The Mechanism transferring the motion of the large gear wheel to the two half axles is a rather clever cam-like mechanism which provides the required motion to the front wheels. This was unmodified from the original fire engine.
The main driver's seat, at the rear, is removable to facilitate access to the regulators and oiler. It is mounted on some scratch-built bodywork. The smaller forward seat is fixed. Both are made of varnished hardwood. The panel covering the boiler at the rear is hinged to facilitate access to the burner. This panel was cut from an aluminium ventilation panel. It gets extremely hot so a small insulated handle is provided. To facilitate steering from a standing position, I've made a long extension which can be clipped to the steering wheel.
Since taking most of these photos, I have added a luggage rack, which improves the appearance considerably. See last photo.