THE GIANT PNEUMATIC: A CONVERSATION
Page 12
Page 13
If you've noticed an error in this article please click here to report it so we can fix it.
The Views of a Man, Prominent in the Tyre Trade, Upon the Giant Pneumatic Tyre, the Economics of Its Use, and the Equipment Which Will Prevail.
TE STEPPED instinctively away from the muddy V roadway as a large van passed us, and in selfjustification for the action looked to see the mud squirted on to the pavement. There was very little to see, but we were interested to note that the wheels of the van were shod with 8-in, pneumatic tyres, and that discovery led us to think of the progress which the giant pneumatic had made in the few years since it was placed upon the market.
We were contemplating the history of the large tyre, reviewing the arguments for and against it and wondering what the developments of the future were likely to be when, immersed in these day dreams (always an unwise state to be in in the crowded streets of London!), we ran almost plump into the arms of Mr. A. S. Bishop, the assistant sales manager of the Goodyear Tyre and Rubber Co. of Great Britain and inveigled him straight into the club, fortuitously close at hand, and asked him if it were not a fact that he had pioneered the giant pneumatic tyre in this country.
" Yes, I may justifiably claim to have done that," said Mr. Bishop. "I went over to the States in 1919 and spent six months studying the problem of larger tyre diameters and investigating the manufacturing and sales position over there.'
"And did you feel that, taking into consideration the fact that British roads generally are better than what are found elsewhere (also speaking generally), the large pneumatic was wanted here 7 "
" Certainly, I was convinced about that, and, when I. got back here, I had no hesitation in making all arrangements to offer the tyre to commercial vehicle users."
"'What do you consider the principal advantage offered by the large tyre ? " "Well, I would place quite high in the list a great economy in the upkeep of road foundations and road surfaces. By the use of pneumatics, large enough to carry the weights that have to be moved by commercial motors, the cost of road maintenance can be considerably reduced."
Some Undisclosed Experiments.
"One of the leading manufacturers showed me" (we said), "the beginnings of a set of experiments designed to prove their contention that solid tyres did no more damage to roads than pneumatics. I believe that the results of those experiments (never disclosed to us or others outside of the concern) rather showed that pneumatics were the better from the point of view of the road."
"I knew of those experiments," replied Mr. Bishop, "but did not hear the results. My own opinion is that there would not be discernible any great difference if the vehicular speed were kept below 15 miles per hour, but over that speed the difference would grow remarkably."
"And, of course, speeds are increasing— I" "Yes, they are, and they must do so if we want efficiency in the carrying capacity of our roads." "The other advantages? What are they?" "Increased speed is one, a lower fuel consumption
another, and greater earning capacity."
"Would maintenance costs be reduced?"
"Unquestionably, both in the matter of the chassis and Of the body. Then, in the case of passengercarrying vehicles, there would be the important advantage of greater comfort for the passengers."
"There must be certain disadvantages : to what do you think they can be brought down?" B28 "Just a higher initial outlay and a greater liability. to tyre trouble. Nothing more." "Then you would say that the disadvantages are completely offset by the advantages? "
"Oh, undoubtedly, much more than offset. Leaving out all the other advantages, of those I have mentioned, the advantage to be derived from increased speed would alone outweigh the disadvantages, inasmuch as a more frequent service can be run or longer routes undertaken with the same number of vehicles."
"Have you any figures on the question of improved fuel consumption? This is a much debated matter, you know."
Pneumatics Mean a Saving in Fuel.
"Yes, it has been very greatly debated ever since the giant pneumatic tyre was introduced. We have, from time to time, received very reliable information that petrol consumption has been reduced anything from 10 per cent. to 30 per cent, after giants have been fitted in place of solids." "What do you say about the cost of running and maintaining pneumatic tyres on a 30-seater or any other kind of bus?"
"The costs would, naturally, vary according to the type and weight of the vehicles, the road conditions over which they operate and the care and attention given to the tyres. There are some concerns running 30-seater single-deck buses on verf light chassis, and the cost of running pneumatic tyres on these would be appreciably lower than on a 30-seater bus body fitted to, say, a J-type Thornycroft."
"Do you mean that you would prefer to base the cost more upon the total laden weight of the vehicle than upon the seating capacity?" "Yes. Proceeding on that basis and, generally speaking, on a vehicle weighing a maximum of 2 tons on the front axle and 4 tons on the rear, the cost of pneumatic tyre equipment should not work out at more than one penny per bus-mile—with a possibility of the cost being around three farthings."
• "Now, take a vehicle weighing, at a maximum, 21tons on the front and 5 tons on the rear, what do you think the cost should be I"
A Tyre Cost of a Penny per Bus-mile.
"Not more than a penny farthing per bus-milewith a possibility of it being somewhere around a penny per bus-mile." "To what rear-wheel equipment would these figures apply?" They would apply equally to single tyres or twin tyres on the rear wheels." "But the initial cost of the single tyre would be somewhat higher than that of the twin tyre!"
"Yes, but the single tyre on an average would give a higher mileage than the twin." "I see. Yes, I had not thought of that! What about the cost of inflation and of supervision of the tyres? " "I am not able to answer that question, t ven approximately: You see, these items would naturally vary according to the number of buses being operated and the number of depots from which they operate." "Let us assume, then, that they are operated from a central depot " "In that case there would be only one air compressor to install and one man could look after a very large number of vehicles, whereas if the buses• were operated from more than one depot these costs would be doubled."
" And would there be any. difference in the cost of supervising single pneumatic tyres and in the cost of supervising twin tyres?" Yes, it is my experience that where buses are operated on single pneumatic tyres the cost of supervision of the tyres is much lower than where twin tyres are used."
" To what is that result due?"
" It is due to the fact that the single tyre is much. lessliable to punctures, and, consequently, has to be changed over much less frequently."
" Talking about changing over, do you know of any long mileages in which no changes. have been deemed necessary?"
" I know of cases where single pneumatic tyres have run more than 40,000 miles without once being removed from the rims."
" That's good! "
" Yes, but do not forget that the mileage covered by a set of pneumatic tyres varies according to the conditions under which they operate and to the make and type of tyre which is fitted." " Well, let us consider the .straight-sided tyre as against the beaded-edge tyre!"
" Some absolutely reliable statistics which I have show that the straight-side tyre will give a much better mileage than the beaded-edge tyre. and on 3.0-seater buses would average better than 20,000 miles per set."
" Now, would you tell me something about tyre troubles—or, shall we say, potential tyre troubles? "
" Pne.utriatic tyres are obviously, by the nature of their construction, liable to give more trouble on the road than solid tyres, but, generally speaking, there are few delays in service through tyre troubles.'
" And, as between the single tyre and the: twin. tyre--?"
" Where single tyres are used, tyre troubles are few and far between, but where twin tyres are used troubles are a. little more frequent. That is my experience."
" What are the reasons for this difference? "
• " With the twin tyres there are six tyres to puncture instead of four, and the thickness of the tread of those tyres is not nearly so great as with the single tyre. Consequently, what will puncture either of the four rear tyres will in all probability have no effect at all upon the itigle tyres."
" What about stones becoming wedged between the twin tyres? "
" They, obviously, cause carcass bruises, which eventually result in bursts."
" Inequality of loading of the rear tyres must be a difficulty! . " Yes, one or the other of the four rear tyres is i
frequently overloaded, owing to inequalities n the road and cambered roads."
• "Then to what do you ascribe the obvious prefer. once for twin tyres? '
" It is all due to the present desire of the builders of chassis and of bodies to get the loading line down to the lowest point."
"And which do you think will prevail? "
"The low load line will probably prove the dominating factor, and, as a result, the twin tyre."