Society of Motor Omnibus Engineers.
Page 27
Page 28
If you've noticed an error in this article please click here to report it so we can fix it.
Discussion on the Paper by Mr. Worby Beaumont.
i:continued from page 8.)
Continuing his remarks, Mr. Parker said that, in the matter of carburetters, they seemed to he going further from the mark. The jet system did not and could not give a consistent mixture at all speeds. It was wrong to try to mix raw spirit with air travelling at such high velocities, and, to his mind, the old form of surface carburetter was preferable, but, better still was the wick system adopted by Mr. Lanchester, and, although it might not be so convenient and pretty as the jet type, if they
were to obviate most of their present engine troubles, via., pre-,
ignition due to carbon deposit, faulty lubrication due to condensation or over saturation, overheating and loss of power, sooted ignition plugs, foul exhaust gases and inefficiency, they would have to fall back on a carburetter of the Lanchester type. With ball bearings on the crankshaft there should be little necessity for lubrication other than by what is known as the "splash" system, that is, the big ends of the connecting rods dipping into an oil bath in the crank chamber. To overcome the difficulty of smoky exhaust, due to excess of oil in the crank chamber, it is only necessary to add another piston ring to the piston, slightly below the gudgeon pin. If one does not have the desired effect, two will make it doubly certain. With such an addition to the pistons, he ventured to suggest, it would be next to impossible to obtain a smoky exhaust, due to overlubrication, and a much larger quantity of oil could, therefore, be used in the crank chamber. Failing this, forced lubrication would very naturally be adopted. The thermo-syphon system of cooling with a modified form of radiator, placed in a better position, would supersede the pump when utility was considered in preference to appearance. They would then be able to keep the engines clean and free from dust. In most of the present systems a fan was used to
pull dust through the radiator and blow it on the engine: the result was more disastrous than it appeared to be. The Rehault system of cooling was a step in the right direction. It kept the engine clean and free from grit arid rendered it very accessible. Whatever clutch, change gear, and foot brake may be used eventually, there should be one common, rigid, bed-plate casting, forming the engine crank chamber, clutch chamber, gearbox and brake chamber, and having a three-point suspension on buffer springs to the main frame, which shuuld be quite straight. Such a unit could be readily lowered from the frame and replaced by a duplicate. In this form, the complete engine and mechanism could be overhauled and tested in the workshops without the main frame and wheels, a special trolley being provided to act as a stand and as a means of conveying same from point to point. So far as he could judge, the old form of Walker metal-to-metal clutch, with various modifications for actuating same (say a means for picking up the driven plates separately), would be hard to beat. A gear-box containing two forward speeds and one reverse would be ample, provided the diameters of the gear wheels were sufficiently large. Noise from these would be entirely eliminated, if well-cut double helical teeth were used. The lubrication with this form of tooth would he perfect. Naturally, these gears would always be in mesh; to effect the gear changing, large diameter jaw clutches with opposed long and short teeth would be used. With such clutches it was practically impossible to miss in changing. The top speed would, of course, be what was known as direct drive. The transmission shaft or foot brake should be practically a duplicate of the clutch, also enclosed in an oil-tight case. They now arrived at the universal joint. There should be two such Joints, one for the transmission of power, and the other for suspending the transmission-shaft trunk or casing to the main frame. The other end of the trunk or casing would be rigidly connected to, or form part of, the gear casing on the live back aide. Here a worm drive would be hard to beat, because of its smoothness of action and, also, because it maintained the transmission shaft in a straight line with the engine shaft. One of the main advantages of this system was the abolition of tension end torque rods, chains, etc., which were the chief sources of noise. He had assumed that ball bearings would be used wherever possible. Dust-proof, internal-expanding brakes, which should be constructed of steel wire in place of wood, on the driving wheels, completed the picture.
They would notice that his picture contained neither petrol. electric, hydraulic, nor any of the systems that threaten the mechanical vehicle with annihilation. Unfortunately for all these systems, they needed a prime mover, the petrol engine. His judgment might be at fault, but he was bound to acimit that if asked to decide which would be the lightest, the least costly
to make, the most efficient in running and upkeep, and require the least experienced staff to maintain, his vote would have to go to the purely-mechanical vehicle designed on broad, simple, practical engineering lines. The two chief faults of the omnibus of to-day were its excessive weight, and the gear-box. By the single-deck body and trailer, the one is removed, and, by increasing the diameter and reducing the number of gears and parts, and dispensing with the sliding method of speed changing, and making the sub-frame independent of the main frame, a step in advance would result that nothing short of a revolution, such as obtaining electricity efficiently direct from heat, would annihilate the purely-mechanical vehicle and the internal-combustion engine with its various kinds of fuel. Other systems would, assuredly, be tried and might prove his theory wrong, but experiments and the present powerful monopolies wouli postpone that for years, and, in the meantime, passengers had to be carried in the same manner as they were carried on railways during the sixty odd years that had been passed in arriving at the successful locomotive of to-day. Now as the problem before the omnibus companies' engineers was, to all intents and purposes, the same as that of the railway companies in the past, surely the experience gained in all these years should be invaluable, and he suggested that the committee of the association should seek permission for its members and associates to visit some of the large railway companies' workshops, cleaning sheds, etc. The author's opinion of workshops, tools, and systems, would be more than fully justified, and, further, the visitors would find that not only did the companies clean, repair, and run the locomotives, but they made them, and their spare parts, and he contended that, sooner or later, the omnibus companies, would have to follow in their footsteps, in nearly every respect. With regard to the road question, the single-deck or lighter vehicle would enable longer and more resilient springs to be used and perhaps some form of pneumatic tire. If the power were transmitted proportionately through all wheels, and all wheels took a part in steering, the road problem and wear and tear would be greatly reduced. In conclusion, he thanked Mr. Beaumont heartily for his paper.
Mr. Flexman French, who said he had had a long connection with the trade, referred to his experiences in running a singledeck omnibus. The earning powers of this, he said, were wonderful. Its average earnings per day were £3 4s. 10d. for the first six months. He showed the cash book to Mr. Thomas Tilling, who came down to investigate the matter, and he had some difficulty in convincing that gentleman of their takings. They generally managed to keep a pair of back tires on a day, but they could never keep their gear-box brasses more than a week. He found, however, that, as soon as he began to take some of the omnibuses off the service, and reduced the service from a twenty-minute one to a half-hourly one, the receipts dropped off. Eventually, they had to give way ; their expenses were so great and ruinous that they could not face the music any longer. Since that he had been more or less connected with the omnibus trade. He had been very much interested in Mr. Beaumont's paper, but he did not think the paper had followed the evolution of the motor omnibus sufficiently up to date, and he would like to hear Mr. Beaumont's opinion as to how .the perfect omnibus was to be evolved. The motor-omnibus companies had now, he thought, got to look at the consumption question. That was where they were going to make the profit. A reduction of a gallon of oil per day on a hundred omnibuses would mean a saving of several thousands of pounds a year. There was not the slightest doubt that they were using far too much lubricating oil, and that no private owner of a car, or the driver, would think of using anything like the same pro-. portion. He had just been driving in a 20h.p. car and they had covered 340 miles using only a little over 3 pints of oil. That was out of all proportion to the quantity •used. in an omnibus. For the past 34 days he had been using half-a-gallon of oil per day on an omnibus he had been trying. They had had no trouble so far and he believed they would not increase that amount. They were only giving out half-a-gallon per day, but he believed some motor omnibuses were using three gallone per day. As to the gear-boxes, they should be cast and in one piece, and there should be no opportunity for any loss of grease. They had not opened their gear-boxes for two months, nor their differential, and they were not going to open them for another month. They were allowing the drivers a pound of grease per day, and that was a very great saving to the
owners. The grease they were using at the present day was simply for the wheel caps. Forced lubrication was, no doubt, something to do with that. They had adopted forced lubrication, but they were going further than that and were going to make the supply entirely automatic and quite independent of the driver. He did not believe that his men had an oil-can at all ; he had never seen them with one. Another very important point that was often overlooked by many of the makers was the pitch of the wheels which was too small. He was greatly in favour of the cog and pinion, and was also in favour of a larger pitch. Both should be cut gear and hardened, for his experience was that the cast-iron pinions cut away very rapidly, and that, before they had used them very long, there was a very great noise. He could not agree with Mr. Parker as to the single-deck omnibuses and did not think they would pay. He found that, no matter what the weather was, a large number of passengers would ride outside and he should be very sorry to have anything to do financially with a company that ran single-deck omnibuses. They would not do even for the country, he believed, although they might perhaps do so. He was connected formerly with a company in the country which ran single-deck omnibuses but they had to convert them into double deckers.
Mr. Leo Harris was keenly interested in the cooling of motor vehicles generally and all that appertained to them, and said he felt compelled to make a few remarks on the paragraph in Mr. Beaumont's paper in which he said, "It is, perhaps, too early to expect it, but it does appear to be desirable that the eugine7 should be provided with a cooling system which does not need the aid of a miniature pumping station, or even of a tin, toy fan." In his opinion, it was not " too early to expect it.' They already possessed those advantages, as those who met there knew. The "tin, toy fan" was no longer with them, at least he had not seen one for a long time, and he presumed it had been consigned to the scrap heap, and radiators were being so correctly and scientifically constructed as thoroughly to cool the highest-powered omnibuses equally well with. thermo-syphon circulation as with the pump. They all knew it was advisable to get rid of the pump. In its present form it was very objec• tionable, but he thought that with the present form of the British-made radiators these pumps could be dispensed with entirely. He was not speaking altogether without knowledge, for he had considered the question a great deal for some time past. He considered one thing faulty with a good many snakes of omnibuses, and that was that the outlet was made far too small. Were the outlet for the radiator increased in size, he believed, there would be a very much greater efficiency.
Mr, Frost Smith was grievously disappointed at the last meeting to learn so little from Mr. Beaumont's paper. From the knowledge which Mr. Beaumont possessed, he hoped to have learned quite a lot. They had a resunif of heavy traction vehicles from the commencement (but that was only of historical interest), and a little of present day construction, but of the future they were told nothing and, therefore, he thought, he was justified in being disappointed. He took exception to the cool manner ia which several gentlemen on the evening in question, got up and told those who were operators what they should do, and many of those gentlemen were not acquainted with what they were saying. (Laughter.) It was only after a lose acquaintance with motor omnibuses that one was entitled to speak upon them. He was dissatisfied with many manutacturers who were entirely unscrupulous. Operators were invariably made the scapegoats, and those manufacturers, when their vehicles ran badly, went straight away to the owners and said, "Look, the man you have got is no good," and then the man got the sack. The average vehicle of to-day was defective and, on average roads, it did not pay. It was because he knew that was so, that he was so eager to hear what Mr. Burford had to say on the future. He took exception to much that Mr. Burford said and could quote a good many instances. As to manufacturing. In the early days, they were obliged to buy a lot from manufacturers and on many of the parts that the latter sold they made three and four hundred per cent. profit. He did not need to go into figures hut he could justify all that he said, exactly. It very often happened, also, that they could not get what they wanted. It was very undesirable to be in 'manufacturers' hands. They could not afford to buy from the manufacturers and, therefore, they had to make the parts themselves. He had been unable to find a manufacturer of speed gears in this country who could make and harden them equal to those made in Germany. Eighteen months ago, there were some extremely noisy omnibuses running on the streets ; to-day there were very few. Ho hoped Mr. Parker would live long enough to see his forecast come true. "I shall be dead." (Laughter.)
Mr. Edwin N. Heriwood directed attention to the portion of _Mr. Beaumont's paper in which he spoke of certain streets and ,roads where the roadway was bad, and about the objectionable
vibration set up by vehicles even where those vehicles ran on rubber tires. He was sorry it had not appealed to Mr. Beaumont to call attention in his paper to a more appropriate use of rubber than putting it upon what amounted to a grindstone. He maintained that the rubber could be used in such a way as to give the greatest efficiency with the smallest possible amount of wear. It could be done by distributing the amount of load within the wheel. That had been dorm in omnibuses where the load had been distributed on 300 to 400 cubic inches of rubber. There was ten times the amount of cushioning material that they could get on twin rubber tires, and the fubber was so little affected by the small weight pressing upon it that it would not wear out in anything like the same time that rubber tires were destroyed. If they took the cubic contents of the rubber tire on a back wheel they would find the pressure was over 2001b. to the cubic inch which was very destructive, and he did not believe that they would find, when they had got the weight of the omnibus on that particular part of the tire between the wheels and the road, that there was any resilience whatever left in the overloaded rubber. Consequently, they found, as a matter of fact, that, as they travelled along the streets and rough roads, there was an excessive amount of vibration which was extremely destructive to the whole instrument and which was a thing that engineers ought to look to and avoid. That would benefit not only the users of the omnibus, like the unfortunate general public, but also the proprietors, and it would save the latter a considerable amount of cost in every kind of way. There was another point: a cushion drive was provided by that same wheel and, therefore, in starting the vehicle, they would avoid the very disagreeable jerk which at present was customary in the vehicles now running.
Mr. Emerson, referring to Mr. Douglas Mackenzie's remarks, said that it was impossible to tell whether the losses made by the omnibus companies were made on the old horsed vehicles or on the motor-omnibuses, and they were careful that it should not he known. Alluding, however, to one route, namely, that from Clapham to Piccadilly Circus, the conductors of the horse omnibuses on the road thought themselves very fortunate if they got enough to pay themselves and the driver. Mr. Beaumont had said that more attention must be given to the requirements of the motor-omaibus engineers. There were many points that probably did not appeal to those who were interested in purely motor concerns. The engineer not only had the defects commented on to contend with, but also had to fight the prejudices of the highest officials, who were used to the old horse-vehicles. When they got officials out of sympathy, it was not conducive to success. The cost of maintenance of the machinery was a sure point with Mr. Burford. Was it not the fact that the operating companies were absolutely compelled to lay down a plant to manufacture spares, owing to the inability of the man ufactiirers to supply such spares in anything like reasonable time? The operating engineers having the plant had been able to carry out improvements in the chassis which, it would have been impossible to have got the manufacturers to do. As to the high speed, he thought that here, Mr. Beaumont had touched the spot. There was no doubt that all the omnibuses running to-day were far too highly geared. There was also no doubt that it was the high speed at which they were driven over London's bad roads that was the cause of all the trouble. So long as it was possible to drive the omnibuses at those high speeds, the drivers would never be persuaded not to do so at times. If the ratio between the engines and the toad wheels were lowered, they ought to be able to dispense with changespeed gears, and he would be inclined to throw the lot out. There was no doubt that an omnibus could be designed, for London, with two speeds only. In the petrol omnibus the top speed could be a direct drive and all that was then wanted was another speed for hill work and starting. Even now most of the work was done on two speeds ; they rarely saw a driver on his bottom gear. If they get a machine constructed on this design, they would not want the petrol-electric omnibus. He agreed with most of the former speakers that the single-deck omnibuses were out of the question, and that fares were ridiculously low. In the region of prophecy, he thought, he was also somewhat disappointed with the paper. Mr. Beaumont had decided not to be a false prophet, but he thought that gentleman indulged in a little sarcasm at those who produced horse omnibuses. As to lifting out the chassis and placing it on the table as a watchmaker did the works of a watch, well, he would like to see a watchmaker with an omnibus chassis on his table (hear, hear). The watchmaker certainly would not require his glass to see the defects. With the difficulties he had mentioned, it was necessary that the engineer should be a very competent man. The figure-head, or paper engineer was not required in the omnibus service. As to the last paragraph in the paper, he would remind Mr. Beaumont that it was not the rule for operating engineers to go to bed (laughter). He thanked Mr. Beaumont for his interesting paper.