Steam as a Motive Power for Public Service Vehicles.
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Discussion on Mr. Thomas Clarkson's Paper.
Cot. R. E. CROMPTON, C.B., was the first speaker. Ile pointed out that he drove a steam omnibus 35 years ago, and re; marked that the application of steam to public vehicles of this character did not become of practical use till Messrs Serpollet, Clarkson and White developed their machines. Perhaps the most pregnant statement by Mr. Clarkson was that in which he asked whether anyone was justified iii assuming that the ordinary methods of steam generation and application represented its highest practical possibilities. So far, hot-water engines, instead of steam engines, had been used ; but, if steam was to be successful against the internal-combustion engine, it would be only by developing superheated steam. The present system of constructing land and marine engines might have to be revolutionised if steam were to compete with petrol or paraffin. It was not until six years ago, when he was carrying out experiments for the War Office, that he became aware of the great value of superheat. In the construction of steam generators of the flash type Mr. Clarkson differed from M. Serpollet. That, however, was a question which was not thoroughly understood at present. Mr. Clarkson had been fortunate in his work with regard to lubrication troubles. In the matter of the engine, it was found very necessary so to construct it that there was no distortion owing to high temperatures. So far as he could see, the mushroom valve was the only type that was really suitable for steam of very high temperatures. He thought that steam as a motive power for public-service vehicles was entering a new era.
Mr. E. W. FULLER, engineer of the Torquay Motor Omnibus Company, said that from three years' experience in the working of the buses of his company, supplied by Mr. Clarkson, he could state that they had worked most satisfactorily One of the first cars in the service had now run considerably over 44,000 miles, and the chassis was still quite good. The first boiler lasted for 18 months, and, in another omnibus, which had travelled over 40,000 miles, the original tubes were still in it. Great satisfaction was expressed on all hands at the noiselessness in running, and, at the present time, they had little trouble from skidding. The results of the working were, in his opinion, all the more remarkable, as the gradients at Torquay were very steep in places, and, so far as he could see, the steam vehicle of to-day was reliable and satisfactory.
Mr. D. J. Stems said that in the Serpollet generator it was possible for steam to be used at a temperature of 1,200 degrees Fahrenheit So far as lubrication at that temperature was concerned, it had been found quite easy. Mr. Smith then gave some figures obtained in the Scottish Reliability Trials, showing that a 40h.p. Darracq-Serpollet omnibus travelled seven miles on one gallon of paraffin, but the best result from petrol was five miles on one gallon. There was no doubt that the separation of the pumps from the engine in the Serpollet type was of the greatest advantage. In the case of flash boilers, the steam was used as quickly as it was generated in the boiler, and, in his opinion, there would be a time when, in negotiating an incline, the engines would be travelling so slowly that the pumps, if driven by it, would not be able to supply sufficient water to the boiler to allow of the generation of steam for the engine. The idea of supplying a complete and independent pump, and feeding the boiler and burner from it, was first used by M. Serpollet. One thing necessary was that no public-service vehicle should show any steam ; at the same time, it was also necessary that the steam should be condensed and returned to the boiler. If that were not done, an enormous quantity of water would have to be carried, and the steam would have to be got rid of by passing it over the
flues and superheating it, a course which was followed respect of steam lorries. One other important advantage of the flash boiler was that it was possible to return the water to the tank and use it over and over again. Although the life of a flash boiler was generally thought to be fairly lengthy, M. Serpollet did not contend that his boilers would last as long as Mr. Clarkson's generators.
Mr. W. ELIOT Titomas, secretary of the Torquay Omnibus Co., confirmed the figures given by Mr. Clarkson as to the running of one of his vehicles. As a rule, their omnibuses ran
from 80 to 90 miles per day, and had to ascend gradients of 1 in 10. During the summer, char-à-bancs bodies were fitted, and those had been run around Dartmoor. Mr. Clarkson's buses had also given much satisfaction in their running on the roads over the sea route at Torquay, where the routes were often-invaded by the sea. He laid stress on the facts of the smooth and noiseless running of the vehicles and of their reliability.
Mr. H. BIRCH expressed great appreciation of the value of the steam motor in the country, and gave some details of an experimental run, with a Chelmsford, which had been made in Wales. The average speed for the 650 miles covered was 12 miles an hour, and even in the hilliest places it made an average of over 10 miles an hour. The load was about seven tons, including 28 passengers. Mr. W. J. TALBOT, of Walsall, pointed out that the steam motor was not looked upon with favour by the majority of motorists, but he could not see why steam vehicles should not prove absolutely reliable if forced lubrication, as adopted by Mr. Clarkson, were used. It was a fact that the boilers of these engines did not scale. Ile was of opinion that the piston valve was superior to the lift valve for this class of work.
Mr. Hass RENOLD expressed the hope that all the members were aware of the excellent results which had attended the Chelmsford cars, and pointed out that no petrol omnibus, accorning to Mr. Clarkson's account, could get anywhere near such performances as his cars. Such results must, undoubtedly, be ascribed to the combined excellence of boiler, engine, and the method of transmitting the power. The speaker admitted that he had no experience of the boiler or the engine, but he wished to say a few words about the transmission gear. Mr. Clarkson's method of transmitting the power was so absolutely simple that the speaker said he must heartily congratulate him upon his achievements, In his criticism of Mr. Clarkson's transmission gear he wished he were not representing a chain concern, for Mr. Clarkson used chains, but, as representing a company which, during the last few years, had supplied 2,000 sets of chain gear for heavy motor wagons and omnibuses alone, he had had opportunities for studying good, as well as bad, applications of chains. The noisy chains on the omnibuses of London had been honoured by the attention of Scotland Yard. After declaring that he was in favour of the use of chains, he alluded to some of the difficulties which had been surmounted by Mr. Clarkson. When chains were of the wrong size or of the wrong type they were noisy, and it was said that the chains broke, but that was always the case when inferior work was used. They, however, seemed to have no terror for Mr. Clarkson, who had studied the matter and made all allowances, and in his gear he had given a very liberal length. The result of the working of the Torquay omnibuses, built by Mr. Clarkson, showed that the wear and tear on the tires was not so great as had been expected. That was very satisfactory, and could be ascribed to two causts (11 The use of steam, instead of petrol explosions, in the engine cylinder ; and (2) to the use of a solid back axle instead of a live axle. In conclusion, he said it. might interest some of the members to hear that experiments were on the way to get some facts and figures about the different results obtained by a car with a live axle and one with a solid axle. For that purpose an 18-24h.p. petrol car was on order, and he hoped that by and by he would be able to read a paper before the members showing the results.
PROFESSOR HENRY SPO.-INER said he was fortunate enough, maneyears ago, to have some experience in connection with
the 'Perkins boiler, experiance which had stood him in good stead many times. Col. Crompton, in his passing references to that boiler, seemed to suggest that the boiler which Mr.
Perkins used was a flash boiler, and he noticed that Mr. Clarkson referred to his boiler as being of the same kind. The boiler had certainly some remarkable qualities, and it was one that,
iii addition, So far as his experience went, was free from any trouble in the way of incrustation. It was, Ire thought, in
1874 or 1875 that there was a Boiler Committee appointed by the Admiralty, and they examined a Perkins boiler which had been in work something like 13 years continuously. They had three of the tubes in different parts of the boiler opened up, and they were perfectly astonished at the remarkable state of preservation in which they found those tubes. He was sure those of them who had seen Mr. Clarkson's beautiful engine at work, and had noticed the ingenious arrangement for lubricating the various parts, must have been struck that the pro vision for supply was more than sufficient. Mr. Perkins devised and made a steam vehicle, about 1871 or 1872, and that had some rather remarkable features. it was worked at higher pressure than the engine they had under review, being worked at a pressure of 4501b. of superheated steam. 'I'hose were the days when they had not the high qualities of lubricants avail able at the present time. Those things did not trouble Per kins, for the simple reason that in the cylinders of his engine he used no lubrication. The astonishing thing was that a cylinder working at that pressure, and running something like 18 months should have been found, when the pistons were drawn, to he in a perfect working condition. The anti-friction metal used consisted of five parts tin and 16 parts copper. Dealing with Mr. Clarkson's reference to his use of the regeneration principle in his boiler, the speaker did not think that principle was applied in the strict sense that it was ap
plied by Stirling and Siemens. He ventured to think that the author of the paper might possibly get a still greater advantage
from his arrangements in the way of utilising some of the heat which was lost in the gases passing to the burner. Continuing, the speaker said he thought they might safely predict that that great principle of superheating was likely to play an important part in the future development of this engine. Certainly, the results which were due to the use of superheated steam were, he was going to say, very remarkable in their effect, but he thought that the more one examined the question the more they might expect. Attention was really first directed to the in crease of efficiency which was due to the employment of super heated steam in 1859, and during the following 10 years there was a rather steady increase in pressures, which culminated, about 1870, by the general employment of compound engines. With that increase of pressures, and the corresponding increase of temperatures, trouble commenced, particularly in con nection with the valves, because, in all cases where superheated steam was used, it was the valves that suffered first. Ti was his humble opinion that, when the flash boiler was proved to be a working success, there would be the dawn of a new era, with a new science whose laws required formulating.
Mr. GEORGES DE PRELLE congratulated. Mr. Clarkson on his paper, and, as engineer of the T.ondoa Road Car Company, said he might tell the members that his omnibuses had given very good results. Mr. Clarkson had compared the steam omnibus with the petrol omnibus. In a petrol omnibus, said Mr. de Prone, they might consider that they had actually ar
rived at nearly the perfect engine. The big drawback in a petrol omnibus was the gears, which, after a certain time' were
noisy, owing to wear and tear and the rough handling by the drivers, but, in a year or two, they would have perfect gearboxes, " which could not be smashed by those men." (Laugh ter.) He then gave some details of a new system of change speed mechanism which he had had fitted to an omnibus, and said the results had been most satisfactory. In closing, he said he should like to express to Mr. Clarkson the satisfaction he had had with his cars, and especially to congratulate him an the marvellous system of lubrication.
Mr. 'VAUGHAN PENDRED asked what was the material of which Mr. Clarkson's boilers were made? He knew that in the boilers that were used in torpedo boats the smaller tubes could not be got to stand at all unless they were made of a very high-class Swedish steel. He also asked whether it was not a fact that in the circular boilers the tubes bent so much that they came down on the burners until they absolutely extinguished them?
Mr. STEPHEN H. TE.RRY said that many of them forgot that Col. Crompton was in this country, and in India, the pioneer of steam for transport, and he believed he was correct in say ing that he once established a through servire of 100 miles in 10 hours. There was an amazing amount of prejudice in certain quarters against steam, and it had been left for Mr. Clarkson to show what could be done. In his opinion, steam was quite able to hold its own against all competitors. Mr. Clarkson had kept nothing back, and had given to the world the results of years of scientific work. (Applause.) He appeared to have solved the question of the petroleum—not petrol —burner, using the oil of commerce which could be bought for less than half the cost of petrol. He went on to point out that, if only a chimney could be used on steam. vehicles, it would save a lot of trouble. He had had an opportunity of inspecting Mr. Clarkson's cars, and he thought that the arrangement for working the pump was a most important one. The heating of the feed water was also of great importance. lk felt that, as Hancock was the pioneer in 1830, so Clarkson might be considered the Hancock of the early years of the 20th century.
Mr. M. Houtow SMITH, after offering his congratulations to Mr. Clarkson for his paper, said he hoped they would have more of such papers read, for they had had too many of an abstract character. Mr. Clarkson gave them full details of what he had done. One of the speakers had referred to Perkins' engines, which were more or less failures, because of the little detail of lubrication. People might have their first principles right, they might have their theory correct, but, unless the details were properly carried out, the whole system would be spoiled. in Mr. Clarkson's case they had theory and excellent detail in combination. The speaker was in favour of mushroom valves, which had been neglected to a large extent by English engineers, but were better appreciated by the foreigners. The interest in Mr. Clarkson's system centred, not upon the enOne, but on the great question of generation. It was the production of the heat, and conversion of that heat into steam, which was really the great problem that had to be solved in this work. They had, therefore, to compare Mr. Clarkson's method with that of other people. A few years ago he had to examine and report upon one of the early White Steam cars, and, unfortunately, it was not favourable. They had, however, advanced considerably since that time, and he had tried to get detailed information from the White Steam people, but he had not succeeded. That was where the English people were so open-hearted and open-minded. Nevertheless, there were points where the two engines could be compared. The first was in reference to lubrication. The difference was that, in the White Steam engine, they controlled the amount of oil that would pass from the vaporiser; in the Clarkson engine, the amount of gas which escapes from the nozzle. It would be presumptuous to state which was the better method. He liked Mr. Clarkson's idea, but he did not like the details of it. Mr. Clarkson gave a regulator for controlling the air, but he had no means of regulating the pistons like the White Steam people had. He was rather afraid that, with the varying qualities of petroleum, varying densities of atmosphere, and the dirt that might get in, that it would be extremely difficult for him to make so many things act automatically. The very marked advance in the boiler on the part cf Mr. Clarkson seemed to he the conical-shaped coils, and he thought he was the first to adopt them. He then criticised the arrangement of having the coils together, and whilst not wishing to depreciate the utility of welding, it seemed to him that Mr. Clarkson's use of it with regard to the tubes was very risky. The White Steam people had a separate piece, which went round each.
Mr. Da= HALPIN also congratulated Mr. Clarkson on the amount of interesting detail he had given them, except concerning the condenser. There was only one detail in the paper which he criticised, and that was the fan, for he thought that class of fan was quite out of place in such a beautiful machine. A fan like that was really beneath contempt when they thought of the amount of power put in without any return.
Mr. E. N. HENWOOD said that since the operation of the Heavy Motor Car Order, at the beginning of last year, the Government had required that all motor omnibuses going 12 miles an hour should be fitted with rubber tires, to which was, invariably attributed all the side-slipping so dangerous to a great number of people in the streets. They might say that when rubber-tired wheels, with double rubber tires on the back wheels, got a load of something like three tons on them, there was a compression that would have a surface of about 30 square inches.
(To be continued.)