Petrol Motor Omnibuses.
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Discussion on Mr. Beaumont's Paper at the Institution of Mechanical Engineers.
Never has the fine hall of the Institution of Mechanical lEngineers held a larger audience than faced Mr. Worby Beaumont when be rose to read his paper on "Petrol Motor Omnibuses.' All attendance records were broken ; every seat was -.filled, and even the gangways and the spaces on the platform, where the President and Council usually sit in dignified isola/ion, were given up to the accommodation of visitors. It says. much for the importance which attaches to motor-omnibus problems that the two leading technical, institutions of this country—the Institution of Civil Engineers, and the Institution of Mechanical Engineers—should have devoted so much attention to the subject. The last-named Institution gave three meetings to the discussion of the steam omnibus in connecticn with the paper read recently by Mr. Thomas Clarkson, whilst the Institution of Civil Engineers gave three meetings to the paper which Col. Crompton has just read before that body. As will be seen from our report, the discussion on Mr. Worby Beaumont's paper was adjourned, which means that the Institution of Mechanical Engineers will be giving more than half the meetings nt the winter session to the discussion of motor.omnibus problems. This is really a remarkable testimony to the great interest which is being taken in the subject by responsible -engineers, who foresee in commercial motor traffic a vast application of mechanical engineering.
More Statistics of Working Costs.
Mr. A_ Campbell Swinton said he had read the paper very carefully and thought,, from the figures given by Mr. Beaumont, that everybody must have been impressed by the impertance of the subject. IIe would like to add a few words on the statistical side of the subject. Mr. Beaumont had pointed cut that motor-omnibuses in London were carrying 185 million passengers per year, but he had come to the conclusion that that number was more nearly 200 million passengers per year, which, according to a recent, statement of Mr. McKinnon Wood, of the London County Council, was, even on the lower estimate, a larger number of passengers than was .being carried by the L.C.C. tramways, the figure given being 180 millions, At the present moment, there were something over 800 motor-omnibuses in service in London, which had cost altogether to put on the road something like one million sterling, whilst the London County Council had spent five millions to instal a system which .carried fewer passengers. He would ask the London County Council, which had proposed to spend another five millions, -whether it would not be a wiser thing to allow the omnibuses to .carry the traffic and save this large amount, a proportion of which might then be very profitably spent in improving the road -surfaces of London, the condition of which was responsible for a great deal of the wear and tear of motor-omnibuses. He -thought Mr. Beaumont was not quite fair upon the motoromnibus official, whom he regarded as a person with one idea, -that of getting as much mileage as possible out of his omnibuses, and not being interested in keeping his vehicles in proper :repair. He had heard that statement made over and over again, chiefly by manufacturers of motor-omnibuses, and, as far as he was acquainted with motor-omnibus management, he was bound
to say it was not a fair statement. Those who were unacquainted with what was being done in this direction by the larger omnibus companies would be much impressed by the amount of trouble taken, and the expensive plant which had been installed, to keep the omnibuses in good working order. The larger garages were equipped with the latest machine tools, and in the charge of a competent and skilled staff of engineers. The speaker went on to challenge Mr. Beaumont's figures regarding the cost of running motor-omnibuses, contending that if the ninepence halfpenny per mile was intended to apply to London it was too low, and if intended to apply to the country too high. In this connection Mr. Campbell Swinton was again able to give the cost for running motor-omnibuses in connection with the Bath tramway system for a whole year. car-mile for the year 1.906. The figures are per These were actual figures which had been obtained in working, • for the previous year, the running cost had been slightly 1e.ss,'7.96d. Challenged at this point on the subject of depreciation, which was omitted from the working expenses, the speaker naively observed that this could be taken at anything one liked, and therefore he had left it out, a mode of dealing with the ticklish subject of depreciation which excited universal amusement. Mr. Campbell Swinton went on to point out that another item, was omitted, the charge against general management, which had not been included because the omnibuses had been added to an existing tramway system and had not increased the cost of administration. Adding .68d. for that item, and 1.30d. for depreciation, it was true that the total was Id. more than that given by Mr. Beaumont. Turning to another matter, he was quite sure that the author of the paper was quite wrong with regard to his allowance for renewals, repairs and lubrication, particularly in London. One reason why upkeep was so much greater in London was the frequent stopping and starting as compared with country services, and the whole subject was not only impertant but called for further investigation,
The Work of Daimler and its Effect.
Col. It. E. Crompton said that the author's reputation and great experience gave his paper real importance. It was full of valuable points, and he personally had learnt a great deal from it. Mr. Werby Beaumont, in common with a great many other writers on the subject, made a great hero of Gottlieb Daimler, and no doubt it was due to him that the present motorcar and motor-omnibus had been brought to their present state of popularity. At the same time, he did not think it was quite fair to say that Daimler was the first man to utilise piston speed to reduce the weight of prime movers. He thought it was right, in the hall of that Institution, to say that their own great English engineer, Wrillans, was the man who did that, making steam engines of a weight and efficiency previously unattained. 'Without wishing to rob Daimler of any of the credit due to him, he thought that the work of Willans should be pointed out. At she same time, it had to be admitted that, although Daimler did much to forward the commercial use in motor vehicles of the internal-combustion engine, he was responsible for the introduction of the great difficulty which attended the working of the intzrnal-combustion engine in the sphere of commercial work. Ile was in a pesition to know that the figures quoted in the paper and by Mr. Campbell Swinton in relation to engine repairs were very largely exceeded in practice. This was mainly due to the fact of the Daimler engine being worked by means of change-speed gears, which was an enormous disadvantage in omnibus working, and was really the main explanation why working costs were so heavy in London. He was a little disappointed that the author, with his great experience, had not made sonic suggestions as to the means to be adopted to over
:ome that difficulty. It would occur to all engineers who considered the matter that there must be some happy medium between the extremely light engine having cylinders of very small diameter driven at very high speed, and therefore necessitating .considerable gearing-up to obtain the required acceleration, and the more direct-driven set having much large' cylinders and a smaller ratio of reduction. He had spoken to the author about this particular subject some months ago, and Mr. Beaumont had then said that a larger engine would be less economical. That certainly appeared to be the correct theoretical deduction, but, as a matter of fact, in practice it had been found that an engine with cylinders big enough to drive on the top speed and never change its gear had been an unqualified success, and had given the unexpected result that, far from its being costly as regards fuel, the omnibus to which this engine had been fitted was the most economical petrol bus that had ever been driven. He believed that, with that engine, 7 to 8 miles had been obtained from one gallon of petrol, and it seemed to him that what had been done suggested one way in which progress might be made in the direction of making the motor-omnibus a better engineering tool than it was at present.
Tire Troubles and the Speed Question.
Another matter that the author had not dealt fully with was the matter of tire troubles. It was true that Mr. Beaumont hinted that a great deal of the trouble was due to the weight of the unsprung parts, so that the tires were perpetually being hammered. In this connection, Mr. Beaumont pointed out that the side chain was fitted to many types of omnibus, hut that gear drives were, numerically, in greater use. The side-chain vehicle must not be lightly condemned; it was largely in use, but hitherto it had not had a fair chance. The space between the wheels and the side chain was so small that it was extremely difficult if not impossible to protect the chain, and it had been most instructive to watch the splendidly-arranged, grit-grinding machinery employed in the London omnibus. A stream of liquid mud was carefully directed on to the inside of the chain, just where it was going under the big sprocket wheel, where it was immediately ground into the chain with results which could be easily imagined. He was sure that a great deal of the noise of the chain-driven omnibus was caused by the neglect of chain protection. The author had said that the maximum speed of the omnibus was too high, and had pointed out the damage caused by that great speed. In that connection, he was hound to say he agreed with these who argued that the popularity of the motor omnibus was due largely to its speed in comparison with the horse omnibus. Unless a high speed was attained when it was possible, nothing like an average speed of 12 miles an hour could be obtained, and, if that speed was to be maintained in traffic, then a maximum speed of 15 to 16 miles per hour was necessary, and was indeed met with in practice. The only way in which the maximum speed could be reduced was to make the engines of great power of acceleration, which, although capable of being done in a steam engine, was not easily done by an internal-combustion engine. He was bound to ask Mr. Beaumont what were his views on the tire question, an intensely interesting subject. Personally, he believed that some form of segmental tire would eventually be adopted. The ordinary ring tire had to be scrapped very frequently because of the difficulty experienced in effecting repairs ; vulcanisation had a tendency to alter the texture of the tire. That led him to refer to the question of garage management, which, in spite of what Mr. Campbell Swinton had said, he did not hesitate to say was a perfect scandal to anyone who knew anything about rubber. Oil in any form was a solvent of rubber, and yet one often saw a garage positively swimming in oil, a matter to which he would pointedly call attention.
Mr. Mark Robinson, referring to Colonel Crompton's statement on the subject of the work done by 'Winans, said that the real cause of the lightness of the Winans engine was not high piston speed but high pressure. It was this that gave the link between the work of Willans and the work of Daimler.
Experience of the Ryknield System.
Mr. W. Flexman French said that he thought Mr. Worts{ Beaumont rather over-estimated the number of continental omnibuses in use in London to-day, and, as a matter of fact, instead of 516ths being of continental make, one-half were British-built, and, of seventy-three exhibited at the recent Olympia Show, fifty were British. He did not agree that no definite conclusions could be drawn as to the cost of operation of single-deck omnibuses, and, on country services in particular, single-deck omnibuses carrying about twelve passengers were preferable to the larger type. Wherever small buses or wagonettes were running, they were proving fairly successful. He had never had any doubt, in watching the development of the motorbus, that London services would eventually call for a 40h.p. motor, such as was fitted to the Ryknield. This power was given at 800r.n.m., 45h.p. being obtained with 1,000r.p.m. One of these vehicles was now running on the trying Hammersmith to Hornsey Rise route. The great engine power increased the maximum average speed, and it was found quite unnecessary to accelerate above the normal speed on an ordinary road. The maximum speed was reached in about 321t. and was attained in a perfectly smooth manner and without shock. Running on half throttle afterwards, they were enabled to maintain the average speed, and, if necessary, to exceed it ; there was no necessity to drop in a lower gear for hill climbing. The weight of the vehicle was not increased in order to attain this flexibility of engine, the chassis weighing 2 tons 19 cwt. It appeared that tire depreciation was less than usual, owing to the road resistance being more easily overcome in starting ; neither was there increased consumption of petrol or of lubricating oil, the petrol consumption working out at over seven miles to the gallon, and lubricant consumption, 234 miles to the gallon. The oil in the gear-box only required replenishing once in 8,000 miles. It was not found that high road speed increased the road shocks, and indeed, owing to the principle of construction and spring suspension, the general opinion was that it was one of the easiest running vehicles in. London. He agreed with Mr. Beaumont that, if hills were to be climbed at high speed, more than 28h.p. was required, and indeed the case for 40 horse-power was well made out. In this connection, he would point out that, in the chassis referred to, an automatic control valve had been placed in the main induction pipe of the engine, which precluded the possibility of the engine exceeding a certain set speed. Up to this set point the driver had a wide margin for contingencies. With regard to friction clutches he did not believe that the multiple-disc type was so good as many believed, and he was of opinion that the simple type could not be improved upon, and certainly they had obtained excellent results from it. He did not think their experience indicated the need of a greater provision for depreciation than 15 per cent. He had had considerable experience with steam vehicles, but they were still to be much improved before they could be used with the same facility as petrol vehicles. He was inclined to think that the electrobus would make some headway, experience in the United States being favourable to that view ; but, before electric buses could take their place in English services, they would have to pass through a very expensive experimental period. He did not think anything was to be gained by using 26passenger omnibuses, as the chassis would be practically the same as for the 34-passenger bus, and he was inclined to think that in the future the tendency would be to increase passengercarrying capacity rather than to reduce it.
Correcting Mr. Beauniont's Statistics.
Mr. Douglas Mackenzie said that Mr. Beaumont referred to 795 omnibuses being in actual commission in London, but since the paper had been written the number had increased to 894. Five-sixths of the number were said to have been constructed in France and Germany, but careful enquiries he had made demonstrated that 344 were of English manufacture, 204 of French make, and 346 of German origin, which was a very different proportion of foreign-made vehicles to that suggested in the paper. Reference had been made to the unreasonable objection to motor omnibuses. He had taken some trouble to go into this matter, particularly with reference to the emptying of houses in the West End. It had been said that places like OnsIow Gardens had had their houses emptied by reason of motor traffic, but, as a matter of fact, the houses now empty had been empty for years past. It might be, of course, that the motor omnibus had come in at the climax, but the motor omnibus was not the cause of these empty houses, as had been alleged. He differed from the author as to the present bodies of omnibuses. It was true that they were nearly all of uniform type, which was an unfortunate fact, due to the regulations of the Metropolitan Police ; these regulations had done serious injury to the travelling public. Had the makers been allowed, provision would have been made for carrying a larger number of passengers on a chassis of the same weight, which would be a great advantage during the rush hours, and, in that case, the unfortunate financial position of the two leading companies would have been different. The author defended the use of single-deck omnibuses, and suggested that experience with the single-deck omnibus in London was too short to allow definite conclusions to be drawn. As a matter of fact, one company which did work single-deck omnibuses on a commercial scale achieved success at the outset, because at that time they were the only motor omnibuses in service. On coming into competition with the double-deck type, it was soon decided to withdraw the single-deck service, and to cancel the contracts placed for a further supply. On the subject of clutches, the author stated that the leather-faced, cone type was that commonly in use. He had taken the trouble to work out the number of different forms of clutches in use in the metropolis. The leather-faced type was largely in the majority, being in use on 725 omnibuses. The single-plate clutch came next, being fixed to the De Dion-Bouton omnibuses
118 in number ; the Hele-Shaw clutch was fitted to 4 omnibuses, the internal-expanding metal-to-metal to one omnibus, and the multiple-plate clutch, which the author referred to as being in use by a number of vehicles, he had been unable to find on any omnibus. Mr. Beaumont had dealt with the question of gear-boxes, and, in that connection, he would point out that, with the cast-iron gear-box, it was impossible to say that such a gear-box made from a particular pattern would come out, in all cases, of sufficient strength. Experience only could decide that In regard to the differential gear of the De Dion vehicle, the design had been altered, the planetary type having been abandoned, and the bevel-gear type of differential substituted, a gear which seemed to him to possess serious disadvantages. He would certainly like to know the reason for the change. Coming to the vexed question of working cost, he thought that Mr. Beaumont had worked them out with great care for the London omnibus of to-day, and he was of opinion that a few years' experience would show that he was very near the truth, as he believed that the figure would be brought down to 10d. per car mile. There were certain items, such as tires, renewals, and repairs, which would be reduced in later experience, and he believed that, when the figures for 1907 or 1908 were available, Mr. Beaumont's estimate of costs would be near the actual facts.
Future for Petrol-electric Systems.
Mr. Pennington (Wolseley Company) said that reference had been made to acceleration, and he wished to point out that the internal-combustion engine combined with electric driving could give better acceleration than even the steam engine. He had been assisting lately in the development of a petrol-electric omnibus of which rapid acceleration and controllability in traffic were the leading features. He believed that we should shortly see petrol-electric vehicles on the streets in fair numbers, es pecially for town work. With regard to change-speed gears, designers had great trouble in getting gears to run silently ; theresult was that some makers had adopted the worm drive with a big reduction, and direct drive for the top speed, and attempted to run on top speed altogether. In order to get gears to run quietly, they should be small in diameter, set up to correct centres ; they were better made wide, and with short teeth. If such a design were complied with, there would be no difficulty in getting gears to run silently. Dr, Archibald Barr said that Mr. Beaumont had given great credit to Daimler as the pioneer in the construction of the petrol motor. As Colonel Crompton had said, there was nothing very extraordinary in the piston speeds of the petrol motor, and the point Mr. Beaumont had not brought out was, that the limit to the speed of the engine was not the limit of revolutions per minute but the limitation of piston speed. The principal reason for the lightness of the petrol engine was that the power was among a number of cylinders_ It was this which led to the very small weight coupled with the high, mean pressure. He would like more information with regard to the various types of clutch. He had been informed that the leather-faced clutch very rapidly deteriorated in omnibus services, but that was not his experience in motorcar work. Dr. Hge, Shaw made reference to the author's statements with regard to the various forms of clutch. Enquiries of the manager of the Hele-Shaw works in Paris enabled him to say that there were 246 of that type in use in that country. He was surprised to hear that only four omnibuses in London were fitted with it ; in Paris there were 90 omnibuses at present fitted with this clutch, and 60 more were on order. They certainly did some things better in France. He brought these figures forward as an answer to Mr. Beaumont's apparently misleading statement.
The discussion was adjourned until April 12th.