GAS-PRODUCER VEHICLES AT THE PARIS SALON.
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A Brief and Interesting Survey of Gas-producer Design in France.
TN view of the fact that there are some 15 makers of gas' producing appliances for automobile work. in. France it may seem surprising that only eight of them were represented at the Paris Commercial Vehicle Show. It should be remembered, however, that the market for gas-producers is, at present, almost entirely an overseas affair. French makers are turning out plenty of gas machines, but quite 90 per cent, of their output goes to far-distant countries in which, owing to special conditons, the gas-producer has an immediate chance of proving its very real usefulness.
In spite of the high cost of petrol in France, charcoalusing gas-producers have not yet obtained much commercial success in the home country. Charcoal, although much more readily obtainable in France than in England, is not available everywhere. For this -reason wood-burning producers
have been, attracting .a good deal of interest lately. .
In the Colonies, however, the case is entirely different. Wood is obtainable almost anywhere except in the North African provinces, whilst charcoal can be quickly and easily prepared with the help of portable charcoal kilns. Woodusing gas machines at the
Salon included those of Berliet and the Societe d'Albret. The new wood-fuel Renault gas machine has not quite reached the production stage and was, therefore, not exhilehed. We understand that this apparatus, which has recently come through long and exceptionally severe road trials with great success, will be placed on the market within the next few months. In its design the rather complicated gascleaning system employed in the earlier charcoal-using Renault machines has been replaced by an arrangement of great simplicity.
The Berliet wood-fuel motor coach, which recently made a 5,000-kilometre tour round France, attracted a good deal of notice on the Berliet stand. A feature of the Bernet machine is the very small space occupied by the combustion zone. This reduction in the fire space has rendered it possible to do away with the usual fireclay lining to the generator, and a considerable saving in weight has been effected. There is another advantage in the elimination of fireclay, as the latter substance is liable to break up when subjected to severe and continuous road shocks, as, for instance, when a lorry is used on bad Colonial roads.
The extraordinary simplicity of the Berliet apparatus probably accounts in a great measure for its successIn using producer-gas on a road vehicle much depends upon the driver. If he will give the machine the few minutes' daily attention in the way of removing dirt from the purifiers, drawing off water, etc., which is all that it requires, all will go welt The human element is, unfortunately, often the weak point in the system.
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It follows that the fewer things there are to be done, and the easier it is 'made to do them, the greater chance the machine will have of receiving any attention at all.
Messrs. Panhard and Levassor showed an example of one of their fine charcoal gas-producers fitted to a 4-ton Panhard lorry. The Panhard machine is a very substantial piece of work. It is remarkable for simplicity in the design of the gas purifier. Several modifications and improvements are incorporated in the latest model. The gas cleaner now consists of a large steel cylinder, the lower part of which is tilled with coke resting on a grid, The gas enters beneath this and passes through the coke to the upper part of the cylinder, where it enters a filter consisting of a number of small-diameter vertical tubes. These tubes are all connected up to a central outlet pipe conducting the gas to the engine. It may be noted that, in the Panhard machine, the cleaning of the gas is entirely a dry process. An encouraging feature of the producer-gas movement on the Continent is the fact that several important makers now turn out machines designed for a particular type of vehicle and practically incorporated in the chassis. Berliet, Panhard and Levassor, and Renault with their new model, are examples of this, whilst amongst the Belgian firms Pipe and Dewald may be mentioned. The Dewald concern actually make a special engine for gas-driven lorries.
Starting up on gas machines has been greatly facilitated during the last year or so by the improved design of mixing valves, etc. This fact was demonstrated during the recent French heavy-vehicle trials, when gas-using lorries were able to get away from a cold start within from four to five minutes of the first lighting up of the generator.
Whilst hand-operated fans for starting up on wood or charcoal alone, were fitted to most of the generators seen at the Salon, the Practice of. starting up on petrol is Stilt employed almost
universally. A s m all gravity-feed tank containing about a gallon of petrol was fitted in practically every case. On Berliet gas-driven vehicles a refinement was noticed in the hand controls for the mixing valve used when turning over from petrol vapour to gas, and for the air valve on the 'emssupply pipe. The controls in question were mounted on the instrument board and incorporated dials showing the exact proportions .or gas and petrol vapour admitted in the case of the mixing valve, and of gas and air in the case of the air valve.
The Also wood fuel-using producer shown by the Societe d'Albret has certain novel. features. As in the case of most modern generators, the furnace is of the inverted type in which the air passes from the top downwards. There are really two furnaces in the Also generator. In the upper, or primary, furnace the wood is converted to Charcoal. The small pieces of charcoal formed by the combustion of the wood fall through a grid into the lower furnace, which constitutes the generator proper. The bottom of this lower furnace is filled up with a number of ovals in fire-clay or porcelain. When the generator is in action, the fire-clay ovals become practically white-hot. They present a very large surface to the newly formed gas, and this, together with their high temperature, serves to dispose of the tars and other by-products of the wood fuel.
It might be thought that the screen of fire-clay ovals would become choked with dirt and ash, and thus interfere with the proper working of the generator. In practice, however, this is said to be avoided by the eiceedingly fine nature of the wood ash and the great heat of the ovals.
One of the most interesting gas-producers exhibited at the Salon was the new Pipe charcoal gas machine. This was shown on the special Colonial-type Pipe lorry, for which the gas-generator has been designed. The lorry in question is a specially high-built version of the standard 2-ton Pipe in which special attention has been given to the suspension, in view of bad road conditions.
Features of a New Gas-producer.
There are certain entirely novel points about the new Pipe gas-producer. Chief amongst these is the fitting of a supplementary radiator, mounted in front of the ordinary lorry radiator, for cooling the water employed in the gaspurifying apparatus. The generator is a simple and substantially constructed affair. It comprises a very large fuel hopper containing sufficient charcoal for a run of at least 100 kilometres on a 2-ton lorry.
Beneath the generator is the gas-generating furnace. This is of the vertical direct-draught type in which the air enters at the bottom. The fire is contained in a basket made from special heat-resisting steel. No fire-clay lining is employed. Water vapour is used in the production of gas and the arrangements for its introduction into the generator are distinctly ingenious. The water is gravity-fed from a small tank to an appliance which resembles almost exactly a petrol carburetter. It comprises a float chamber, air intakes and jet. From this the water vapour enters directly into the generator and mingles with the hot gas.
The first purifying process is designed to dispose of the ash and larger impurities. It comprises a cylindrical chamber containing a steel cone. The gas enters the chamber at a high speed, strikes the Cone and then leaves the chamber again by a right-angled pipe. The brusque change in direction given to the gas causes the deposit of heavier impurities against the cone. After leaving this first cleaning box the gas makes a complete circuit of the chassis through a largediameter pipe which is attached to the exterior of the frame.
The principal gas-washing appliance is situated on the side of the chassis opposite to the generator. It consists of an oblong steel box placed vertically. In the interior of this •box is a cylinder containing steel spirals. • The gas enters at the top of the box and passes downwards through
the spirals. At the same time water enters at the opposite side of the box and is sprayed through a number of small holes from Which it falls in the form of asort of fine rain. -This water is kept in circulation by a rather special 'type of pump coupled to the magneto-drive cross-shaft 'at the front of the engine. The pump is particularly designed with a view, to resisting any possible damage from grit or dirt in the water. The gas, on reaching the bottom of the central cleaning cylinder, passes downwards through about 8 ins. of water and bubbles up again into the space between the walls of the cylinder and those of the oblong box. Thence it passes into a second chamber provided with a:large baffle' plate, and from this to the mixing valve on the induction pipe of the engine. Petrol is usually employed for starting.
We had hoped' to see the new Tulloch-Reading gas-producer on view, perhaps' made by a French concessionnaire. It is England's most successful producer, a development of Col. D. J. Smith's invention.
Other Gas-producers Exhibited at the Salon.
Other exhibits in the way of gas-producers included the G.H.P.E.A. and E.T.I.A. machines, two of the oldest French makes in existence, and the S.A.P.A.M,E., a newcomer. Makers of gas-producers in France appear to have an extraordinary predilection for initials! All three of these machines use charcoal as a fuel.
The G.E.P.E.A. and E.T.I.A. appliances are almost too well-known to need much description, and full details of both have been given upon more than one occasion in these pages. Both machines are examples of the classic type of gas-producer for road work. In the E.T.I.A. generator the gas_ is actually produced on a series of perforated cones placed above the furnace. A small boiler is provided, the feed water for which is heated in one of the gas purifiers. Hot air saturated with steam is admitted under the grill of the furnace.
The remaining portions of the apparatus consist of a dust extractor and a washer. The gas immediately after formation is allowed to expand between two concentric cylinders. While doing so it throws out the dust. The gas, although now free from dust, contains a certain amount of smoke. The latter is removed in a washer placed on the opposite side of the chassis. This washer consists of two concentric drums about one-third full of water. The gas is siphoned through the water and finally passes out through a series of filters in the centre. A good feature of the design is the fact that no water is carried in the actual producer portion of the apparatus. The furnace thus cannot be drowned out at any time. The E.T.I.A. was shown on a Delahaye lorry.
The G.E.P.E.A. generator is of the vertical up-draught type. Water vapour is used in this machine also. The boiler is enclosed in a box which forms the first chamber in the gas-cooling and dust-extraction part of the appliance. As in the case of the last make described no water is carried in the actual generator. The furnace consists of a simple fire-clay cone. From the dust extractor the gas makes a complete circuit of the chassis and reaches the washer. The
latter consists "of two chambers in which a. very thorough cleaning is given to the gas. In the first chamber the gas is bubbled through water at the bottom, and at the top passes through trays composed of metal rings covered with grease. The second chamber contains a wire basket filled with steel turnings which have been dipped in oil.
The S.A.P.A.M.E. is another gas-producer on classic lines. Although a new arrival, it goes back to first principles— vertical up-draught furnace, separate boiler for water vapour injection, etc. The only special feature noticed on this machine was the provision of an electric motor for the starting fan. This was intended for connection to the ordinary lighting accumalators of the lorry.
One feature of the gas-producers shown at the Salon was a general tendency to make the machines more substantial, in view of the conditions under which they are likely to be used. General strength and resistance to road shocks are of more importance to the Colonial user, who is at present the only user, than even the question of weight or space occupied.
A year or so ago great efforts were being made to reduce weight and to turn out more compact machines. This idea was commendable up to a point, so long as strength was not sacrificed. Whilst, however, the small and compact machine may satisfy the captious but non-buying European critic, all that the Colonial user asks for is something that will give good service under very severe conditions. Appearance is of quite secondary importance, as a rule, in partially developed countries. It is ability to cope with hard work that is required. The French maker understands this and builds his machines accordingly. This is not to say, however, that compactness cannot be combined with strength in a generator. The small and light type will eventually be made quite as strong as the heavy machine, without any doubt at all.