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Meaningless Classification of Tyres

7th April 1950, Page 55
7th April 1950
Page 55
Page 56
Page 55, 7th April 1950 — Meaningless Classification of Tyres
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Which of the following most accurately describes the problem?

THE load-capacity handicap imposed by the Society

of Motor Manufacturers and .Traders on the tyres fitted to British vehicles destined for service overseas seems to arise from the wrong use of the word " overseas" in the Society's tyre-capacity tables: Surely the differentiation should be in conditions of service, rather than between countries of operation.

Thete. are many bad roads in Britain and there are many• roads in other lands which are at least as good as the best in this country. Vehicles operating from quarries, building sites, etc., in our own country are subjected to conditions much worse than, say, those on Carrier work in Adelaide, Paris or Rio de Janiero. Average operating conditions overseas are probably worse than the average at home, but such an argument must sound academic and hypothetical to the Continental vehicle user.

Atmospheric temperature is an important factor in the operating efficiency of vehicle tyres, so that a lower load rating would apply, On this basis alone, td tyres fitted to vehicles for use in West Africa; Singapore or Venezuela than to those for service in Scandinavia or Tristan da Cunha. This point also has a bearing on the other aspect of tyre fitment which you mention—wheel-rim size.

On the question of rim size, it should be pointed out that the more recent S.M.M.T. standards have, in this respect, been moulded on American tendencies, without due regard to the practice of American manufacturers, whose influence is new.

A further item which vitally affects the selected tyrc equipment, and sometimes the rim size, is the maximum permitted width of the vehicle.

The whole problem is beset with difficulties, but merely to divide. tyre equipment into two well-nigh meaningless categories, " home " and "overseas," is to simplify it too greatly. To •renarrre the categories " normal " and "very arduous" is probably a somewhat doubtful solution, but this would be at least a step in the right direction.

Wolverhampton. JOHN C. STEWART.


QU RELY the answer to the problem of a rigid tow

for commercial vehicles can be found in the A piece, or triangular tow attachment? Its use on all vehicles might be facilitated by a recessed radiator cowl. The assembly .could be secured to the normal bumper bar by means of a simpie male and female joint, the lugs of the A piece fitting into, and swivelling in, sockets incorporated in the front bumper.

At the rear of all vehicles should be a straightforward tow hook of self-locking design. This must be deep enough to take the apex ring of the A piece of any towed vehicle.

In the event of a tow being required, all that is necessary (assuming the disabled vehicle is fitted with the attachments described), is that the A piece be released from the recessed radiator cowl, swung through approximately 90 degrees and hooked to the rear of the towing vehicle. The towed vehicle would then be controlled from the cab in the .normal manner.

In the event of damaged steering, ,the usual suspended tow would still be necessary, but any device to surmount this difficulty would probably be costly and complicated.

There is nothing new in this letter, but might not the fittings I have described become by law as much part of vehicle equipment as, for example, mud wings? The tow bar might, in fact, be incorporated in the design of a vehicle, as added radiator protection while it is in the folded position.

Vienna. J. A. D. HART.

CONCERNING your leading article entitled

"Provision for Towing," published in your issue dated March 17, and the letter from F.C. Forster in the same issue, I spent most of my time during the war in either towing or being towed in a number of different countries, I can only agree" with him that every vehicle should have towing hooks, or a least, a ring, even if this be on only one side of the chassis.

As regards the coroner's suggestion for a towbar to be used, I am much against the employment of such a device. Having been in charge of a vehicle towed by one of these, I consider that they. are most dangerous. This is because, if the front vehicle has to brake suddenly, the tendency is for it to throw the towed machine either out further into the road or on to the path.

I consider that every commercial vehicle should carry a wire tow rope equipped with chains and shackles at each end. Hooks on such ropes are not satisfactory as they are apt to come off one or other of the vehicles when the rope becomes slack.

Dymchurch, Kent. 3 HARRIS.

TRAFFIC INDICATORS WANTED AT REAR OF BUSES WHY are traffic indicators not fitted at the rear of " buses on town work, as they often are to longdistance coaches? Usually, the off-side window in the cab of a stage carriage is not large enough for the driver to give a signal that a following driver or rider can easily see, especially in heavy traffic. The cyclist, in particular, is at a disadvantage, because he cannot see the signal at all unless he makes himself a public menace by riding in the middle of the road.

Worcester. P. C. HOLDEN.

SUGGESTED DIFFICULTIES WITH ' SINGLE DECK TROLLEYBUSES THE reference to Glasgow's proposed experiment with a Continental single-deck trolleybus, made in your issue dated March 3, was of considerable interest. No doubt such a vehicle of the type which is to be seen, say, in Rome and elsewhere, has many advantages, but at least in one respect the low roof will be a serious disadvantage in the streets of Glasgow.

With much higher double-deckers all round, low trolley arms sweeping the streets at an uncomfortable

angle might make the steering of the vehicle a task of some skill. In London, trolleybuses often perform outstanding feats at the farthest possible point from the overhead lines, but the arms clear the roofs of other vehicles with ease. It seems to me that this could not be done with those based at a lower level on a singledecker, also, because of their steep angle, such a vehicle could not move far afield

Only by a large out-of-place frame, disfiguring the roof, could the arms be safely accommodated. Such an improvization becomes especially necessary when it is remembered that the trolley wires overseas are usually set lower than those in Britain.

London, S.W.9 G. R. DAY.

'A HARDY VETERAN IN WALES THE enclosed photograph [which we reproduce—ED.] is of what I claim to be one of the oldest vehicles that was in service in Wales until recently.

Made by the Napier concern in 1911, it was used daily until 1949. The mileage is not definitely known, but is estimated to be about 500,000. The body is the original and was built of teak by Mr. Nicholas, of Pcntre. During the recent war the solid tyres on the front wheels could not be replaced, but later a conversion to pneumatics was carried out by me. At the same time a Bedford passenger-chassis rear axle was fitted, mainly so that the vehicle could have four-wheel brakes.

The chassis is of a long-wheelbase type specially built for the fitting of the furniture-van body. The vehicle has given little trouble during its life. Perhaps this was partly due to the fact that in the early days it was regularly maintained by the Napier concern in London.

It has travelled over almost every road in Great Britain, hut has now come to rest in the Vale of Glamorgan, where the body will be used for storage purposes. The work which it formerly performed is now being carried out by a Bedford van.

One interesting point is that this Napier was in the hands of the same driver for 30 years.

Gelli. Pentre, Glamorgan. T. ALDRIDGE.

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