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Weight and "C "-Types.

10th May 1917, Page 10
10th May 1917
Page 10
Page 11
Page 10, 10th May 1917 — Weight and "C "-Types.
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Which of the following most accurately describes the problem?

By "The Inspector."

There is a curious appropriateness in the fact that the authorities who are responsible for licensing public-service vehicles to ply for hire should have chosen the present period of reduced rations in most thinge to announce their intention of insisting 'on lower tare weights for London's motorbuses. The true significance of this pronouncement and of the time chosen for it is, however, probably the unique reduction of London motorbus rolling stock for one or another war reason and the obvious necessity for replacement in the reasonably early future. Plans for weight-cutting, therefore, may well be taken in hand at one.e. Will the tramcar be similarly considered, and if not, why not ? The joint noise an vibration nuisance of the rail-bound tramcar far and away outdoes anything.sinailar for which even the 34-ton motesbus is responsible.

This decision of Sir Edward Henry and his advisers only, of course, applies to the Metropolitan vehicle particularly, and it may at first be said that it is of very little interest to other commercial-motor users.

But I think that is a short-sighted and ill-informed view. Indirectly, there is not a reader of THE COMMERCIAL MOTOR who is not concerned, and that for several reasons which I will endeavour to set down.

I wonder if the effect of London motorbus-operating experience and design on the whole science and art of industrial-motor vehicle construction is often considered. Most of us recall the origin of the present London General motorbus, popularly known as the "B-type." There was no public performance on the part of the A-type, although I believe I am correct in saying it saw daylight at Walthamstow. The real predecestor-of the B-type was the X-type—a not altogether successful venture, • with engine, gearbox and hack-axle troubles of its own. And this, the first machine specially designed for high-speed passengermotor service for use in towns in large units, was frankly admitted by its designers to be a crib from every one of the many types of chassis with which the various bus companies in London at first experimented —with the exception, perhaps, of the Orion and the Scott-Stirling. The X-type was a new cross-breed, and very much cross at that ; it struck out a new line, and was conceived in a very critical period of motor haulage history.

With 'the London bus companies, on account of higher cost of maintenance particularly, as well as of the frequency of breakdown, it was a case of X or nothing. Its improved offspring soon followed. And I claim that the B-type had an enormous and beneficial effect on heavy-vehicle design all round. There are very few modern heavy industrial chassis of today in which there is not more or less evidence that their designers have not very closely 'studied the Walthamstow 'factory product. Its performance particularly gave confirmation to -the use of the steel road wheel, separate hind-wheel twin brakes, the wormdriven back axle, the absence of radius rods and torque bars, the laminated clutch spring, the pull-up brake, the tubular and cast-headed radiator, and the use of plain rather than gilled tubes, and so on and so on. The B-type, a design born of necessity, did a tremendous lot to "improve the breed of British, aye, and of certain French and American commercial motors. For that reason, if for no other, anything that affects its present design is of very considerable moment to users of all classes to-day. There is, however. another important point to consider, and that is the increasing tendency for other licensing authorities, with but tiny problems of this kind to consider,

040 unquestioningly to follow London's lead, and so save themselves trouble. The London-type bus chassis is indeed a hall-mark from Melbour9e to Middlesbrough, from Dalston to Durban—even in New York.

The B-type was a revelation in weight-cutting, and had you asked any of its producers if they could knock another few ounces off the tare weight they would have told you "only by leaving off a coat of paint." Weight-cutting is an old pastime—or shall I write nightmare 7—of almost every draughtsman. The most astonishing exhibitions were probably in connection with the older types of no-limit racing cars. I have personally assisted at several such orgies of skeletonming, drilling holes through any and every pessible part where it was thought air would do just as well as steel or even as aluminium. Spring pins drilled handsomely down the centre, springs scraped and polished on every leaf, rubber used instead of small coil springs, all nuts cut down to nearly half their proper thicknesses, radiators robbed of all the tubes they dared dispense -with, coachwOrk (sic) made of basketwork and leather straps, and finally, the driver put on war rations to get him down a stone or so.

Such expedients as these were of little commercial use, unless to test the ability of designs and materials to stand un to enormotts stresses for relatively, short periods of serVice. Commercial-chassis weight-cutting must be on a saner scale altogether ; it must not and will not consist of after-thoughts. The vast accumulated experience of the London bus-operating interests will enable a great deal of practicable cheese; paring to be carried out while the C-type is being schemed. The National steamer is the only other one to be affected.

Weight-cutting calks for the highest possible skill on the part of the designer. You remember that anyone can build a bridge, but that it takes a very clever one to construct one of the least possible material. Danger may as easily arise through making detail parts -too heavy as too light, particularly when the surrounding structure is all cut to the finest possible limits. Generally speaking, the reduction of unsprung weight makes for lower depreciation, given the same speed, but even then it has to be remembered that nothing is so destructive to a chassis as bumping along at high speed on bad roads unloaded. I know of trouble that once existed owing to the continued fracture of rather a long cross-steering tube. It was cut and cut and still it failed, first at one place and then at another ; we were all obsessed with the idea that it was too heavy and that the consequent vibration was the real trouble. We eventually tried wood with steel reinforcements and straps—witb more disastrous results than ever. The cure proved to be in doubling the weight of the whole cross rod! So much for the difficulties of weight-cutting.

Now for a little prophecy as to the directions in which weight economy may, perhaps, prove to be practicable when the Associated Equipment Co. get to work on the C-type, for that is more er less the limit of the problem set by Scotland Yard. I am with the Editor, who, a fonts-tight ago, plumped for the wheels and tires as being the most likely point of attack. Smaller wheels and lighter, and perhaps with the cushion tires he suggests, may prove to be a useful improvement, the clearances to look after themselves. Some improved form of wooden cheel may vet be produced, one Without spokes, but with adjustable solid wedge body co railway lines. Of engine-weight reduction I am sceptical, unless we reach the turbine or are prepared to employ a higher commercial piston speed. Most of the spring weight to be saved will be in the gearbox, and the French designers are the men to show how best that can be done. Whether noise troubles can be -eliminated other than by the use of a chain gearbox has yet to be seen. Car chassis have shown improvement. Battery lighting evidently offers scope for investigation, as do the advertisement plates. . A "Pretty" Problem.

The problem is a very pretty one, and its solution will be sure to have its effect right through from all but the lightest of delivery wagons up to the five-ton steamer. It is to be presumed the task only has been set by Scotland Yard and that they are hoping for the A.E. Co. to achieve it, not themselves knowing very clearly how. Similar official re-strictions7have worked wonders before ; they may again. But of one thing I am sure, and that is that it will be unwise to go near the A.E. Co.'s chief draughtSman while he is trying. to chop that 10 cwt. off the 3 tons and a half. He'll . certainly tell you to," Weight and C." Here'sto tho "C typo" when it comes through.

Tags

Organisations: Scotland Yard
People: Edward Henry
Locations: Durban, London, New York, Dalston

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