Steam as a Motive Power for Public Service Vehicles.
Page 19
Page 20
If you've noticed an error in this article please click here to report it so we can fix it.
Discussion on Mr. Thomas Clarkson' s Paper.
Dr. H. S. HELE-SHAW was the first speaker on Friday last, and he, Like most of those who had preceded him, referred to the work done by the'audior 4 the paper in appreciative terms, pointing out that if Mr. Clarxson .had done nothing more than to produce the boiler employed, he would h achieved something which called for qualities allied to geniuS. Dr. 1Iele-Shaw said he spoke with some knowledge of the subject, and of the many problems that had to be solved before the steam omnibus became a commercial vehicle, as he had been one of the judges when Mr. Clarkson had exhibited his first successful vehicle eight years ago. In the earlier type of omnibus the arrangements were somewhat simpler than those which now obtained, but, in spite of the apparent complexity of the pipe system, he ventured to say that not any one ot the pipes shown in Mr. Clarkson's plan was superfluous. The condenser was a marvel of ingenuity, and Mr. Clarkson was the first one to achieve real success in that direction. A system of the character employed involved entirely new methods of regulation, for the supply of liquid fuel had to be regulated both while the vehicle was at rest and in motion, a combination of circumstances which had hitherto baffled every other inventor except M. Serpollet, although many attempts had been made to solve the problem in the last 100 years. The result of this automatic regulation was that a man absolutely ignorant of the mechanical details of the system could take his seat on the box of a steam omnibus in London and drive it all day. That was an ideal system. Another matter to which he might refer was the reserve of steam pressure for climbing gradients. It was most remarkable to notice how, when more power was called for, the pressure rose from MO to 1,000 lb. ; at this latter figure he had, on one occasion, wanted to leave the vehicle, and had only kept his seat on the assurance that the boiler had been tested up to 7,000 lb.
In conclusion, Dr. Hele-Shaw said that he had had an opportunity, while in Paris, the previous week, of noting what had been achieved by foreign firms, and he was of opinion that vie had nothing to fear from any steam omnibus which might be sent to us from abroad.
CHIEF INSPECTOR BAssoli said that the official view was that the most perfect vehicle possible should be put upon the road. It would, probably, be said that he was a destructive critic, but he hoped it would be admitted that Scotland Yard never put any obstacle in the way of steam omnibus development save what was absolutely necessary from the point of view of the safety of the public. Indulging in a short retrospect of the history of the steam vehicle on the roads, the Inspector expressed surprise that more rapid progress had not been made. He pointed out that the system of steam tramways, which was formerly in operation in North London, had proved unsuccessful, and that a service of steam omnibuses which, in the earlier days, had been running in the Hounslow district, had been discontinued. Even at the present moment, in spite of the advances which had been recently made, out of about 800 omnibuses in London, mechanically propelled, only about 40 were of the steam type. He would leave others more competent than himself to explain why it was that the number of steam omnibuses was so small, but he would like to join issue with Mr. -Clarkson on one or two points.
His first point related to the claim made that the Clarkson system employed a safe and cheap fuel. The fuel used wae ordinary paraffin, and, while paraffin might be safe at low temperatures, it seemed to him to be by no means a safe fuel at the temperatures employed in the steam omnibus, and he cited as evidence of this fact the number of fires that had been reported in the steam vehicles running in London. Some of these accidents, no doubt, might be due to want of knowledge on the part of the driver, or, possibly, to a defect in the burner, hut, whatever the cause, it militated against the claim that it was a safe fuel to use. On the subject of cheapness, he would point out that, whilst paraffin cost omnibus companies about bd. per gallon and petrol as much as 10d., the question of performance had to be considered. Mr. Clarkson claimed that he could get 21 miles out of a gallon of paraffin, but in practice this worked out at about two miles, whereas the same quantity of petrol yielded about seven miles, so that a comparison of prices with performance rather disposed of the notion that paraffin was a cheap fuel. At this point the speaker reminded his audience that, at Scotland Yard, they had no axes to grind, and looked impartially at steam, petrol, or electric omnibuses, and would even regard an aeroplane service from Oxford Circus to the Bank with equanimity. (Laughter.;
Continuing his criticism, the Inspector dealt with the absence of smell, which was alleged to be characteristic of the steam omnibus, but said that experience by no means supported that statement. Nor, while admitting flexibility of the drive, could he support Mr. Clarkson's claim as to simplicity of control. In addition to steering, there were little matters incidental to burner regulation, foot-pedal, throttle, and the watching of various dials, and when to all this was added the problem of watching the traffic he thought the claim of simplicity of con. trol was not sustained. Many people were inclined to blame the driver when an accident happened, and entirely to acquit the system, but he thought that, if these critics were put to the task of driving a steam omnibus, they would probably be among the first to get into difficulties. Nor was the burner such a simple arrangement as it might appear at first sight, and, in relation to this, he drew upon his own experience. He said that, in making a test a few days ago with a competent engineer in attendance—for at Scotland Yard they did these things, as well as criticise and put obstacles in the was of inventors—it fell to his lot to start the burner. That was said to be an operation occupying about 50 seconds, but he had personally manipulated the starting handle for about 10 minutes without any result. The engineer thought then that plenty of flame had gone through to heat the burner_ The tap was thereupon turned on, and a lot of liquid paraffin passed through; in the end they nearly burned the place down!
Another point was the control of the flame, which he thought might be considerably improved. Reference was also made to the smoke problem. It was true, said this critic, that Mr. Clarkson did not claim that the steam omnibus was absolutely smokeless in operation, and, as a matter of fact, the amount of smoke emitted by the steam omnibus was rather alarming. As to the causes for this, the excessive cooling of the vaporiser had been mentioned, and, of course, that would be so because you would sometimes get liquid paraffin passing into the burner. Another cause might be want of sufficient air, which gave too rich a mixture, and, if that were so, it seemed to point to the fact that the burner was not giving sufficient suction. He sug. :gested that perhaps Mr. Clarkson would consider that point. and sec if something could not be done to minimise the smoke nuisance.
Coming to the next point, that of the suggested canopy in .order that the products of combustion might be discharged upwards, the speaker said that was rather a sore point with Mr. Clarkson. The authorities of Scotland Yard objected to the canopy for reasons that were well known, and perhaps there was no object in going into that question.
Mr. CLARKSON here interposed with a suggestion that he would be glad to hear the official view on this point. Mr. BASSOM, continuing, said the main objection appeared to be connected with wind-pressure problems. He left it to other authorities to state what the wind pressure would be, but his view was that it would be something enormous, thereby making largely increased demands upon the engine. The questions of eide-slipping, tire destruction, and the danger of overturning were also to be noted, and, in his opinion, the collapsible canopy was altogether out of the question in view of the extra responsibility which would be thrown upon the driver in manipulating it.
When the speaker went on to say that Mr. Clarkson was (Inc of the first to recognise that he had to take things as they were, and to meet the conditions imposed, the meeting showed some symptoms of impatience. The Inspector, however, was not to be deterred from expressing his opinions, and added that it was quite open to some inventor to devise a method by which the products of combustion could be discharged into the air if such a course were necessary.
Dealing with the skiding problem as one of the most serious of the difficulties in connec.tirm with the mechanically-propelled omnibus of the day, Mr. Bassom said that he had noted, in connection with the steam vehicle, a greater tendency to skid
ding than with the petrol omnibus. He offered, as an explanation of the fact, that the vehicle carried two large tanks, one
filled with oil and one with water. That weight of liquid was outside the wheel base and a good deal of the weight was carried at the back of the vehicle. Some of the London roads were cambered more than was necessary, and, when the vehicle got on to the camber, there would be a surging movement in the tank, and it might be that this accentuated the skidding. If he might throw out a suggestion, that, might be overcome by putting bulkheads in the tank, to prevent the liquid from swaying backwards and forwards. With regard to steering, this representative of Scotland Yard had also something to say. He stated that the steering of the Clarkson omnibus had heen found to be somewhat slow. He did not know why that was so, and suggested that it might be due to the fact that the thread of the worm was rather fine, or to the excessive weight at the front end of the omnibus. He
pointed nut, too, that in the Clarkson system use was made of a flexible arm to take up the arc movement, and that might
have something to do with the slow steering, In any case, whatever the reason, he thought it was a point that required very careful watching. Lastly, on the brake question, he said that, in spite of the throttle control being available, a driver in London had to depend on his brakes to a greater extent than one might imagine, and he added that the brak.s of the steam omnibus had not been found very satisfactory. The internal.
expanding brake on the road wheels was very difficult of adjustment, and those who knew anything of adjustment work in a garage would understand that when a thing was difficult it was very often neglected, with the result that a driver was sent out with an imperfect brake. The other brake was also rather difficult of adjustment, necessitating taking up part of the Poor boarding.
Mr. fonsis-ros asked for particulars of the working of the London omnibuses. He agreed with what had been said on the
subject of the smell emitted by the steam omnibus, and, whilst
agreeing with Mr. Clarkson as to the energy available for overcoming the inertia of starting, he rather had his doubts as to the
reserve for climbing hills. Indeed, he had seen petrol omni buses passing a steam omnibus at the top of a hill, the reason being, be believed, that the boilers began to prime, and, in stead of getting superheated steam, hot water and steam was
going through, so that the engine became a hot-water engine rather than a steian engine. The Clarkson system of regulation
did not provide for that emergency, the only remedy when that happened being to shut the feed off, which was clearly not automatic regulation. No doubt the Clarkson system of lubri cation worked very well, and be had himself used a somewhat similar device. He noticed that Mr. Clarkson only mentioned two pumps, but the illustration showed four pumps.
Mr. WORDY BEAUMONT, juiste., said it was surprising that a steam :pressure approaching 1,000 lb. on the square inch, and
running up to 1,200 lb., could be used successfully and economi.
cslly with small steam engines of 20h.p. Systems of control had settled into two types : that in which the control of fuel
and water was entirely automatic, and that in which it was done by the driver. Experience indicated that, in point of view of economy, there was very little to choose between the best results of either system, but, from the point of view of the driver, automatic regulation, if successful, was to be preferred. He agreed with what had been said that wet steam was occasionally obtained, and that in this respect one could not entirely depend on the indications of the pressure gauge.
[Mr. Clarkson's rely is, unavoidably. held over until next week, when it will be given in full.]