Normal Ratings for X Tyres on High-speed Coaches
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BY A SPECIAL CORRESPONDENT THE Ministry of Transport, leading bus manufacturers and some big I operators have, during the past few days, been told by the Michelin Tyre Co., Ltd., that X tyres of single-ply steel-cord construction may safely be used at the normal ratings on public service vehicles cruising at sustained speeds up to 65 m.p.h. This important announcement coincides with the opening of the London-Birmingham motorway on Monday.
Buses Granted to Replace Trams
PPLICATIONS by the Leeds Transport Department to run cross-city services to replace the last trams. tit will be withdrawn in November, !, granted by the Yorkshire Traffic tmissioners at Leeds last week, Tram ices will be replaced by buses ween Cross Gates and Horsforth, ton and Stanningley, and the central station and Temple Newsam.
here were objections, to the Cross m-Horsforth service, by Samuel ;aid, Ltd., and the British Transport imission. Mr. Arnold Stone, deputy f traffic officer of the department, that the route would give the type lirect east-west cross-city service the irtment were trying to develop. He not consider that there would be raction as the rail journey was tin, quicker and cost ld. less.
ORTH WALES PARCEL BASE OPPOSED
sl application by British Road Services for an A licence for five eles, totalling 144. tons, to be based Aandudno with a normal user of -eels and smalls. North Wales, Lanire, Cheshire and Midlands" is to be ned by independent operators, incluMessrs. Williams Bros., Qucensferry. is proposed by 'I.R.S.. who have no orized base in the North Wales tat district, to delete a similar number ehicles from Liverpool licences.
W. RIDING TALKS ON BAN ETINGS of union officials and the management of the West Riding unobile Co., Ltd., have been held week. Discussions have taken place erning new duty rotas and ideas for rig the dispute affecting 500 drivers conductors at the company's Belle depot at Wakefield. The dispute been going on for more than eight s, during which time additional overhas been banned by the crews.
ELVIN HALL TOURS GRANT ■ 1 extension of tours and excursions 'rom the Clyde coast to Kelvin Hall, gow, was granted to Clyde Coast ices, Ltd., Ardrossan, by Mr. W. F. 1, Scottish Licensing Authority, at gow last week. The company wished in two coaches each from five towns, iding Ardrossan and Largs, but were ved only one each, with a starting not before 6 p.m.
Any bus or coach chassis designed on the basis of the 30 m.p.h. rating is, when fitted with Michelin X tyres, suitable for fast motorway operation without any increase in tyre size. Moreover, Michelin have promised that if sustained speeds above 65 m.p.h. are demanded in the future, they will still be able to quote safe, but slightly lower, loads for X tyres.
These decisions follow prolonged highspeed tests conducted in Morocco, last summer, with two vehicles equipped with standard production 9.00-20 X tyres. Ambient temperature averaged 107° F. and cab temperatures rose to 120° F.
A two-axled lorry weighing 11 tons gross was driven for 10,000 miles at an average speed of 49 m.p.h. A six-wheeled articulated outfit of 18 tons gross averaged 42 m.p.h. for 9,400 miles. Although 70 m.p.h. was attained on occasions, there were no tyre failures.
The ratings now approved for giant X tyres on public service vehicles cruising at 65 m.p.h. at home and abroad are:—
These inflation pressures are based on individual axle loads.
The basic reason why X tyres can safely be used at such high speeds and weights is their cool running, The amount of heat generated in a tyre increases with the square of the speed, and, at high speeds, with the cube. At 60 m.p.h. the heat generated may be four times greater than at 30 m.p.h.
Temperatures as high as 250°F. are reached in conventional multi-ply textile tyres and progressive diminution in the strength of rubber compounds begins above 160° F. Tests have shown that even after several hours' continuous running at 65 m.p.h., temperatures for X tyres do not exceed a safe level.
At least three of the largest tyre manufacturers have been licensed to use Michelin patents for the construction of single-ply steel-cord tyres.
MOTORWAY DELAY
TITbuilding of a motorway between ristol and Birmingham, which was to have started this month, has been delayed until next March because of legal difficulties. The highway will cosi £8m.
Chevrolet Now Using Torsion Bars
TORSION-BAR front suspension has been adopted by Chevrolet, of America, for their latest models of medium-weight lorry. Lighter vehicles have this kind of springing on both axles, whilst heavy models will shortly be equipped with coil springs at the rear instead of leaf.
A three-cylindered oil engine is being developed by the Detroit Diesel concern for installation in taxis to compete with engines of British make now being fitted to some Plymouth vehicles.
To justify their claims for exceptional operating life, the Ford company stripped down a V8 Super-Duty petrol engine which had completed over 25,000 miles. It was found that 70 per cent. of the components were capable of completing another 50,000 miles. None of the valves needed to be replaced.
The results were held to indicate that the oil engine no longer has such a great advantage in respect of durability.
BEST IN THE WORLD
THE Scottish public was the best in the world and Scots bus drivers never waver in their duty towards them, said Mr. James Amos, chairman of the Scottish Omnibus Group, in Edinburgh last week.
Suggestions had been made that buses were unsafe, he said. The answer to this was that only one in every 70 m. passengers was killed. " In the running of any bus business the public has a lot to do with it. We in Scotland have the best public in the world," he concluded.
SLFNDAY TICKETS SUCCESSFUL
EDINBURGH'S summer Sunday travel tickets were a major success this year, total sales numbering 135,707. Mr. W. M. Little, general manager of the transport department, has told the transport committee that this figure was nearly double that of last year. Similar tickets will be issued in 1960.
Capital expenditure for the department. in the next three years will be £1,284,000. This will cover bus replacements, the Marine Gardens bus depot, road reinstatement and other needs.