Sell-Starters for Industrial Vehicles.
If you've noticed an error in this article please click here to report it so we can fix it.
By Henry Sturmey.
I see the Adams Maimfacturing Co., Ltd., in connection with its entry into the field of connnercial-vehicle work, is embodying an engine starter—or " self-starter," as it is somewhat incorrectly called. This is a move in the right direction, and it is one, to which attention must be given by all those who are interested in one or other of the branches it the commercial trade at no very distant date, because it works out as an .f..; a. d. proposition for the user: The idea is, of course, to provide some mechanical means by which the engine can be started from the seat—by pulling over it lever, or by touching a button, without having to go round to the front and haul round the crankshaft with the starting handle. So far as the commercial-vehicle owner is
concerned, he may very possibly at first sight say, What has this got to do with me? I do not drive the car. That's what my man is paid to do, amongst his other duties.– He may possibly, if he has heard of the movement, look upon it merely as a device to cave the lazy pleasure-car owner trouble, But further examination of the question Will. I think, show that the matter is really of more importance and should be of even more interest to the commercial-vehicle user than to the pleasure-car man.
I am referring more particularly to the light-load, shortjourney class of vehicle, I am willing to admit that there is not so much in it in the ease of heavy-load wagons, which, as a rule, run fairly distant journeys from point to point and stop at either end a considerable time to load up, or to unload. But for the wagon of the retailer and the wholesaler who supplies shop-keepers, with its 20, 30 or more short stops per day, the point is one well worth consideration. To save time and trouble, the driver leaves his engine running when he stops to snake a delivery. It may he running 10 minutes, or ever more, and although he will have throttled down, it is using petrol all the time, and this consumption will mount up sn the course of a year.
Three principal systems.
As the matter, therefore, is undoubtedly worth consideration by commercial-vehicle users and manufacturers, it may not be amiss briefly to summarize the situation, which I have been looking into very closely for the last three or four months, Broadly speaking, there are three systems available for the purpose, apart from the purely mechanical methods of the release of self-coiling springs. The first. of these, the electric system, can, however, I think, be ignored by the commercial user, mainly on the score of its necessarily high initial expense, for there have to be batteries and a dynamo for generating Current, with neces.ary connections, and, although the same outfit can be arranged to supply a set of electric lamps, these are luxuries which can be avoided.
Next, we have the compressed-air method, which is the system adopted by the Adams Co. Where a car is built to take it. this system is undoubtedly good. Broadly speaking, it consists of an air-compressing pump in connection with the engine, and this comgresses air into a storage tank, from which high-pressure air can be drawn for the purpose of starting the engine, either by means of an air motor designed to rotate the crankshaft, or by passing the air through a distributor to the top of each of the four pistons. This latter installation, Iii conjunction with a special valve arrangement, exerts an air pressure above the pistons in succession, thus starting the engine on its cycle of operations. Tf it is desired to incorporate the system on a complete chassis, it necessitates a fair amount of pulling about of the engine, andalthough less costly than an electric outfit, it costs a good deal to fit. So far as the commercial-car user is concerned, when adopting this system, unless he be the user of the very lightest class of commercial vehiclewhich employs pneumatic tires, lie does not obtain any advantage from the means, which this system pros-ides, for the ready inflation of tires.
The acetylene method.
The other system whieh is available, consists of the employment of acetylene gas, and this may be embodied in two ways. In the first place. a storage tank of acetylene is required, so that there may always be a supply .of gas "on tap," so to speak. In one method the gas is passed through a distributing valve to each of the cylinders. which it is enabled to enter by the employment of a nou-retisr» valve embodied in the halfcompression tap. This puts a charge of acetylene and air into the cylinders of a " dead " engine and enables an initial
explosion to take place when the switch is put on—with battery ignition of course. In the other method of its employment, the gas is led from the tank through a mixing valve to the intake of the engine, which it enters at a point between the usual carburetter and the valve. This latter is quite the simplest and cheapest system to install, as the only fitting to the engine which is required is to tap a thread in the engine manifold and carry the lead to it. Several different forms of mixing valve are in use in America to-day, but the best is arranged to be connected up with the switch, so that there can never be any forgetfulness on the part of the driver. What is done is to switch off the current in the usual way when stopping the engine, and, either automatically, as in the case referred to, or by hand, simultaneously to turn en the acetylene-gas supply. The last expiring strokes of the engine as it runs itself to rest, therefore, draw in a supply, not of petrol mixture, but of acetylene mixture, which is thus ready in the cylinders to restart the engine when the switch is turned on. At first, the advantage of employing acetylene. in this manlier may be difficult to perceive, and it may he asked why petrol will not do as well? Thu reply is simply this, that the petru'. drawn into the cylinder of an engine is not drawn in as a gas, but as a spray, and although 801111: of it is gasified and mixed with the air, the bulk of it, when the engine. cools down, will be deposited on the walls of the cylinder and very little better than pure air is left under compression in that cylinder which stops on the firing point.
Acetylene, however, is a stable gas. It enters the cylinder as a gas, mixes with the air as such, and remains unaltered, in addition to which it has an enormously wider range of ignitability, that is to say, an explosive mixture of petrel and air ranges only from about 4 to 10 per cent., whereas the range with acetylene gas is more like 4 to 60 per cent., therefore, it is not very material, with acetylene, in what proportion the gas is admitted. So long as there is gas there, the chances that the engine will fire when the current is switched on. are about 10 to 1. as compared with petrol. The system is inexpensive to fit, although cost varies with the different outfits, but an efficient outfit can be installed for about 12 guineas.
America favours starters.
In America, more that' 60 firms in the pleasure-car trade are fitting their cars with self-starting devices, and by far the majority of them are employing one or other of the acetylene outfits, whilst about a dozen of the American manufacturers of commercial vehicle-s are doing the same. In so far as the supply of gas is concerned, there are two methods—the high pressure and the low. With the high-pressure tank, acety
lene gas is stored at. 500-600 lb. pressure. A specially constructed tank, filled with packing material and an absorbent mixture is employed, the gas being passed through a reducing valve, for use. But in the States, the low-pressure system is coming rapidly to the front, this consisting of a combined tank and generator which produces the gas automatically as required and stores it at a pressure of 3 or 4 lb. per square inch only, these tanks being replenished by merely inserting a fresh charge of carbide as with an ordinary generator. Highpressure tanks require to be sent to a central depUt for recharging, and this makes their use expensive.