Steam’s last bow

There’s something magic about steam engines; enthusiasts are still building steam powered motor cycles in the 21st century. And in 1912 at least one manufacturer reckoned that a steam bike could compete head-to-head with the new-fangled internal combustion.

WE HAVE REFERRED previously to the possibilities of the steam motor bicycle, and in 1909 published a description and photographs of a steam sidecar machine, which was actually in use for some little time. It is now our pleasure to make the announcement that Messrs Pearson and Cox, Ltd, Shortlands, Kent, who are manufacturers of light steam cars, have been giving considerable attention to the question of propelling a motor bicycle by a steam engine. They have been experimenting for about two years, and have evolved the machine which is the subject of this article.

The Pearson-Cox steam motor bicycle: A, water tank; B, paraffin tank; C, steam release valve; C1, steam release valve lever; D, boiler; D1, water control valve lever; E, steam pipe.

The illustration of the complete motor bicycle shows it to be fairly neat and by no means displeasing to the eye.
The engine is set in the old Ormonde position behind the saddle tube, and the diamond frame is taken up by the water tank, while fitted transversely across the forward ends above the footboards is the generator or boiler. The engine has a single acting cylinder, and develops 3hp, with a bore of 1¾in and stroke of 2in. A single acting engine is the most simple type, and dispenses with the need for glands and packing. There are very few parts, which are as follows: cylinder, piston, flywheels, connecting rod, crankshaft, two mushroom valves, and a simple type of plunger pump, worked by an eccentric off the crankshaft. The valves are operated by means of cams and rockers, the cams being keyed one to each side of the crankshaft. The valves have a lift of 3/32in and rarely need attention. The feed water pump is of the vertical plunger type, having double suction and delivery valves. The generator burner is of the horizontal Bunsen type, practically noiseless, and burning paraffin; it is fitted with a hand operated valve for reducing the flame when the machine is at rest.

Starting from Cold.
In the present model the starting is somewhat crude and takes about ten minutes, but in the new type a small spirit lamp will allow the main burner to be lighted within five minutes. The generator consists of horizontal layers of specially drawn weldless steel tube, the various layers forming four sections, which are coupled together by means of unions placed outside the rectangular casing. A section, therefore, can be replaced with ease if one be damaged. It is impossible for the generator to explode, owing to the small quantity of water and steam at any time in the generator and to the extremely strong form of construction afforded by the small bore tubing, which will withstand a pressure of 7,000lbs to the square inch, although the actual working pressure varies between 100lb and 500lbs to the square inch.

The controls: C, steam release valve lever; D, water control valve lever; I, paraffin pressure gauge; J, steam pressure gauge.

The drive from engine to the back wheel is by a single chain, and the gear ratio is 3½ to 1. The inner flange of the large chain wheel acts as a bearing surface for the internal expanding rear brake.
On the occasion of our visit to Messrs Pearson and Cox’s works we were interested to see the machine started up from cold. In the first place, a small quantity of methylated spirit was poured into a trough running round the burner soaking several wicks and then lighted. After about ten minutes sufficient heat was obtained to allow the paraffin carried in the tank behind the saddle to be turned on, while pressure was obtained by means of a hand pump fitted to the offside of the machine, until the gauge in the pressure tank on the near side showed a pressure of 30lb to the square inch. The paraffin vapour valve was then opened and the burner lighted.
As the engine is of the single-acting type, and depends upon its own pump for delivering water into the generator, it is not self-starting, and, in consequence, the machine must be walked for a yard or two before it will start. On the stand it is only necessary to pull up the back wheel slowly once or twice.
At this stage we must say a few words concerning the control, which is of the simplest possible nature. Adjacent to the offside handle-bar grip is a lever controlling the quantity of water supplied to the generator, and close to the near side handle-bar grip is a Bowden lever, which, when raised, closes the steam release, to which we shall refer later.
To start the engine the feed water control is opened to its full or nearly fullest extent, and after the back wheel has been turned round the engine will start slowly at first and then rapidly accelerate. The water control lever is then adjusted till the machine assumes a speed of twenty- five or thirty miles an hour, and then left in this position. This position of the water lever provides ample reserve for hill-climbing, or for a short burst of speed. To stop the machine it is only necessary to let down the steam release valve lever on the near side, which instantly allows any steam there may be in the generator to pass into the water tank.
We were allowed to take the machine to the nearest hill, and found it very easy to control and start, and capable of extreme flexibility, so much so that it could be turned round in the ordinary suburban road without the rider dismounting and with the engine ‘firing’ at every stroke.
On the hill, which was approached at a particularly slow speed owing to the appalling nature of the surface, as soon as the water control lever was opened the engine took hold and brought us to the top at a very smart pace, easily beating as regards acceleration a well-known machine with 3½hp petrol engine which was following. Naturally, this brief trial was totally insufficient to give any idea of the capabilities of the machine during an extended run, but we hope to have an opportunity for a longer trial at no very distant date. The machine we tried is absolutely the first of its type, and a few further points concerning it may be of interest.

The power unit: A, paraffin tap; D, water control valve; F, double-acting water pump; H, exhaust pipe.

The moment the water reaches the generator it is flashed into steam, and passes through the steam pipe (the lagged tube shown in the illustration of the complete machine) to the cylinder. After having done its work the steam enters the exhaust pipe and passes through two tubes on either side of the generator casing, on the lower portion of which holes are bored. The exhaust steam is, therefore, able to get rid of the by-products of the burner by creating a down draught, and it issues from the pipes in an invisible form, owing to its high temperature.
Although only of the single-acting type, the engine has a considerable advantage over the four-cycle petrol motor, as the piston receives an impulse every down stroke. As the hand control is entirely on the quantity of steam the boiler is allowed to generate, it will be seen that, by turning on the full supply of water, the steam pressure is immediately raised, and the engine will develop its full power on a steep hill, even if travelling very slowly; in consequence no change speed gear is necessary.
Owing to the fact, however, that the engine is not self-starting, a plate clutch in the hub would, perhaps, be desirable, or self-starting could be obtained by the use of a hand pump to inject water into the generator tubes.
The advantages claimed by its makers are silence, smoothness of running, great flexibility, and wonderful hill-climbing power. The present type carries sufficient petrol and water for about forty miles, but the new model will have a stroke of 2¼in in place of 2in, a new type of generator (the burner of which can be started in about five minutes) and larger water and paraffin tanks.
The line elevation shows how the latest model will look when finished, and we certainly think readers will agree that the design is very neat and symmetrical. On the new model the water and fuel capacity will be sufficient for seventy miles, and the fuel will cost about 4d a gallon. Whereas the experimental machine weighs 145lbs the new one will weigh 150lbs. Engine lubrication is by crank case splash, a hand pump being situated on the forward part of the tank, from which a charge of air-cooled or special steam oil must be injected every nine miles. The maximum speed on the road is between forty and forty-five miles an hour—surely sufficient for reasonable minded tourists.

Elevation and plan views of the production version. The engine has been mounted vertically and is slightly lower than on the prototype.