Motorbus Weight.
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The Call for Improvements on Present London Practice.
By the Editor.
We published last week the text of the notification by Sir Edward Henry, as Commissioner of Police of the Metropolis, to the effect that he will at some future date require existing practice in respect of London motorbus construction to be u:iodified by the adoption of appreciable reductions in weight. We referred. to the notice as being one in the nature of a "bombshell." It is certainly regarded that way by not a few leading members of the industry, confirmation of which view we have personally received during the past ten days.
Conference Before Action.
We hope that due effect will, in fact, be given by the authorities to the statement in the circular that "any representations which the manufacturers -may put forward will, of course, receive the most careful consideration." It is not the first time in the history of the London motorbus worla. that New Scotland Yard has caused a feeling akin to consternation, thereafter both promising and giving consideration. We do not take up space by qubting the old discussions, features and points ; they still linger in the minds of practically all Concerned, but we refer to the old precedent of interchange of views as one of value. Time must be allowed for discussion. There must be round-table conferences • between the representatives of the police, inclusive of their mechanical and traffic experts, and. representatives of motorbus manufacturers and proprietors, before anything definite can be settled.
Undue Haste to be Deprecated.
We see no reason to anticipate the adoption of any policy of undue haste by Sir Edward Henry and his staff. We also see no reason to fear that a suitable period will not be sanctioned by them before the withdrawal from service of existing types is required. Any road with 6 in. of concrete below its crust should bear the present type of motorbuses at speed, as does Castelnau, Barnes, if road damage is advanced in favour of hurry. Circumstances are such that a period of at least four years from the present day is the lowest one that we can conceive as being admissible, if the claim of after-peace employment for labour in motor factories is to be heeded. We decline to believe that the London police wish to bring disaster upon the industry, as precipitate action by them undoubtedly must.
Two Sets of Experts at Work.
We have oursel3es invited the attention of Sir Edward Henry to the fact that an expert committee of the Local Government Board has yet to present its report on terms of reference which cover the construction and use of motorbuses. We are satisfied that he and his advisers do not seek to ignore the existence of that L. G.B, committee, the extent and value of the evidence which it has taken, or its recommendations when they are presented to Parliament. Those recommendations, we may remark, -should be available a few months hence—certainly before any definite results of the new proposals from Scotland Yard can approach final and official form.
Weight Can Be Brought Down, Given Time.
We might write at great length on this vexed subject. We might adopt the time-worn journalistic method of going round the industry in order to fill several pages with individual views—stated in publishable and more-or-less discursive language. We 018 have consulted representative members of the industry, and the following brief comment, although we trust it will befound to the point, is in part based upon their expressions of opinion to us,but to a greater extent upon our own convictions.
The weight of London motorbuses can be brought down, and can be brought down without sacrificing the seating capacity. It is not possible to achieve this desirable end under war conditions, seeing that manufacturers have their whole staffs and resources exclusively engaged upon war output, but there is no reason why some of the necessary preliminaries— the conferences and discussions—should not proceed in advance of the peace. A perfected type of motor, bus is the ultimate aim of all who are concerned.
Fewer Seats than 54 are Inadmissible for the Poor Man's Motorcar. .
There must be no sacrifice of seating accommodation. That solution cannot be entertianed by anybody for one moment. There may, one day, be a proportion of smaller motorbuses, but the 34 seats of the popular model should go up rather than down in number. Furthermore, there is no necessity for a reduction of the poor man's seats, from whatever source any hint in that sense may originate, and be what they may the alleged reasons for any concession in the, direction of smaller vehicles: Smaller vehicles are not wanted. A traffic situation which can accommodate electric tramcars and trailers is not incommoded by motorbuses of the present overall dimensions, whilst millions of members of the public, as users of passenger-carrying vehicles of all types in the Metropolis, have thoroughly assimilated the motorbus unit as they, now know it. Points of technical detail within the structure as a whole do not affect the man in the street. He know,s nothing of them, but he knows the value to him of a seat in a motorbus to and from his door.
• How to Save Weight but Retain Seating.
We observe from the text of Sir Edward Henry's notice, that he and his expert advisers, presumably Mr. Worby Beaumont, M.Inst.C.E., and Superintendent A. Bassom, both of whom have devoted much study to the problems in hand, consider that the ex-, isting limits of weight must be lowered. Those limits are 31,tons unladen weight, or, alternatively, a gross weight, fully laden, of six tons. These advisers, and possibly others, have led the Commissioner to anticipate that improvements in materials and designs will allow a reduction of weight to a useful extent. The object in view, it is stated, is to remove the causes of "annoyance and damage through noise and vibration," although the motorbusee are "fitted with rubber tires, as provided by the Heavy Motor Car Order, 1904." Proceeding to detail, Sir Edward Henry specifically mentions reductions of weight in the transmission mechanism, the engine, the lighting equipment, and the outside advertisements.
We are 'preparedto urge the motorbus companies to agree that something can be done, rather than to adopt a nom possumus attitude. They will not be allowed to adopt the latter, if they would.' There is, we feel, no occasion for them to seek to adopt it. They must move.
Speed Up the Engine 1 Gear Down the Back Axle.
Something clearly can be done to get weight down. For example, it is not in accordance with modern practice that a motorbus engine should run at the present low r.p.m. of the L.G.O.C. average—say, only 700.750 r.p.m. for 12 m.p.h. on the road. Modern practice suggests at least 850 r.p.m. for that road Speed. Smaller engines, of higher r.p.m., with aluminum pistons 'and other improvements of recent acceptance, will allow a reduction in weight. A certain amount of weight can admittedly also be taken Out of the transmission throughout, not excluding the back axle and it casing, but we attach most importmice to the possibility of a reduction in the unsprung weight. We refer to the wheels, and we are not forgetting the 'road-clearance difficulty. The ratio of Worm-wheel to worm Might go up to 8 or 8 to 1. The police must give way on clearances; accumulated records of accidents do not, we gather, show cause for retaining the old 'clearance under the worm-gear • casing.
Reduce Wheel-diameters from 40 ins. to 56 ins.
The practice in London is to use a 40 wheel. We are prepared, to-day, to revise our earlier views, and to state that a 36 in. wheel is sufficient. A set of 40 in. wheels, if the Belgian class of steel and workmanship ire obtainable, approximates 600 lb. in weight ; some of the Wheels which are now being delivered exceed this limit by nearly 200 per cent. It is this very considerable unsprung weight that does harm to certain roads, as well as to the vehicles, especially having regard to the small depth of section of rubber tire which it is the custom to use. We will now contend—and we are prepared to justify our contention if necessary—that a 36 in. wheel is better practice. The difference in angle of contact between . the periphery of the wheel and any definite obstruction, for a 36 in. wheel instead of a 40 in wheel; is not appreciable, but the lessening of unsprung weight and the lowering of the centre of gravity are of sonic 'account. Clearances may present difficulties on the :undersides of the axles, but. conc6ssions,we repeat; • can be granted by the Police in order to gain other advantages.
Modify the-Springs to Compensake.
The springing must receive a littlejnore attention than heretofore, by-the adoption possibly of the Cary type of spring, in which, whilst all the leaves do not come into bearing at the same time, there should not be sufficient space between the lower group and the toP group of leaves to allow dirt and grit to get between them at any time. . This point, possibly, is more in the nature of detail. Improvement of springing there must be, to compensate for reduction of wheel diameter. • Cushion Tires the Best Means of Relief.
The most-promising direction of all in which we foresee improvement is .that of the substitution of a cushion type of tire for a so-called solid-rubber tire. We have before us amazing records of achievements by cushion tires, and it is to the credit of the N.A.P. tire that these records concern that class and make of tire.
The writer accepts the responsibility of forecasting that the cushion tire will within the next few years double the popularity of the motorbus, and not in London only.
Experiments of which he has knowledge, and in one case the use of such a set of tires on a large motorbus (unloaded weight, 4. tons ; loaded Weight, 7i tons) showed plenty of life left in them, after use on the driving wheels extending to 29,000 miles of City running. We repeat it—twenty-nine thousand miles. This is no idle story. We vouch its accuracy. The significance of the record will at once be apparent to those who are best qualified to judge.
Has the War Given New York Pride of Place?
It is, perhaps, not inappropriate, as we are going to press with this issue, that we should have before
us the latest information con,cernng motorbus practice in New York City. That practice,, as is well known to not a few of our supporters, was originally based on London performance, but it appears to us that it has of late years gone ahead of London's best. The New York chassis, to carry a 44-seated body (weighing 32 cwt. and finished in a style which is relatively luxurious to that of the present London bus), weighs only 48i cwt. This achievement, for commercial service under the load named and on very bad roads, is proof that something appreciable can be done to reduce the weight of the Present London chassis without sacrificing safety. The gross weight of the New York bus, under full load, is much beyond the permissible limit in London. We agree. Our point is that the chassis which carries that great weight is not heavier than the London chassis which has to carry one which is very much less. We have, here, therefore, an important point on which London designers arid engineers can get to work: They are also to be asked by the police, we mideestand, to go closelY into the matter of improved distribution of Weight as between the front and back axles. The chain gearbox will also probably be discarded.
Body Construction and Lighting Equipment.
We understand it is common ground that certain reductions in weight can be effected in respect of the electric-lighting outfits and the body details. The police themselves require a battery of sufficient capacity to run the lighting of the 'vehicle for five hours, in the event of breakdown of the generator, and this requirement accounts for, possibly, some 8.0 lb. of avoidable weight, if reliance can be placed--as we think it should-upon the generator in conjunction with a smaller battery.' As to body construction, one obvious direction in' which Weight can be reduced is to substitute the enamelled-iron advertisement plates by boards of papier mache, or to make some equivalent change.
The drivers and the public alike suffer, at the pre. sent time, from inadequacy of bodywoil in several respects, in that the former h&c no side doors (re'movable in hot weather) to protect them in cold weather, and that there are no sliding or other doers at the back of the vehicles. We do not seek to insist upon the introduction of these additions. We wish to point out that it has been impossible to provide them, so far at least, on account of the absence of any margin, in hand for the body-builders—subject to Police approval—to make them standard. We consider that the possible saving of weight on body construction is the least hopeful of all, apart from changes in the lighting sets (subject to police approval) and the advertisement fittings.
We shall next week hope to publish a few comments upon detail suggeStions for reducing engine, gearbox, back-axle and wheel weights. Correspondence is aim) now invited.