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Opinions and Queries
Page 91
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Jeremiahs at Work
ALTHOUGH not a wheel has yet turned on any of the home motorways, the Jeremiahs have already started predicting gloom and disaster. " Murderways " and "mass slaughter" are descriptive words, reminiscent of enemy wartime propaganda, where half a truth was made to carry an entirely opposite meaning.
Much of this sort of thing will blind public opinion to facts and turn it against fast road travel, without which road transport will stagnate and vehicle exports decline. The critics forget that, other than in built-up and special areas, there is no speed limit on private cars on the existing road system, which is entirely unsuited to high road speeds.
The inference must be that commercial vehicles are the niggers in the wood-pile, and care will require to be exercised lest a campaign be started against higher road speeds and the possible accident potential of the "Juggernauts."
It is generally accepted, other things being equal, that the larger and heavier the vehicle, the safer it is to handle, with better braking and greater resistance to skidding under normal conditions. One of the fears concerning the motorway is the chain-reaction pile-up type of accident, caused by closely following vehicles travelling at high speed.
Whilst this danger may be minimized by stipulating greater distances between vehicles, it will not entirely eliminate the source. One of the problems in the initial years will be the varying top speeds of goods vehicles. Excluding small types following the private-car pattern, this range comes somewhere between about 32 m.p.h. for older vehicles and the 68 m.p.h. of a recent new model of 14 tons gross: a top speed which may be exceeded before the older and slower vehicles are all scrapped. Add to that the differing temperaments of drivers, from the timid to the downright reckless, and the situation is such that considerably more overtaking than is advisable may occur.
It may be feasible to have an " overtaking " ban on short runs like the Preston by-pass, but it will be next to impossible to enforce it on longer leads. On twoand even three-lane roads, overtaking by a goods vehicle will bring it into the path of the still faster car, and the stage is set for the first kink in the chain.
In circumstances like this, emergency braking assumes much greater importance, the results of which cannot be accurately forecast without experience. Braking and tyre development have made vast strides in recent years and will continue to do so, but the governing factor and limitation of all braking standards is the coefficient of friction between tyre and road, It is here that commercial vehicles, with their larger area of tyre tread and bite on the road surface, score heavily. Any general step-up in orthodox braking to all types of vehicle, will produce a liability to fast skids in emergencies.
Some of the now-obsolete trams had a magnetic braking system whereby eight brake blocks, four on each side, were carried in a horizontal position and parallel with the wheels. On application the blocks were simultaneously dropped on to the tram rails. Being metal to metal the results were, perhaps, not always happy, but there was no denying the great retardation. It is possible that this principle could be adapted to motor vehicles as a supplement to the existing brake. If the technical and manufacturing problems were overcome, the area of contact between vehicle and road, and consequently the coefficient of friction, could be doubled or trebled. The first reaction might be that road surfaces would be torn to ribbons. That need not be the case, any more than the locked wheel produces at present.
Higher speeds also call for new thoughts on the security of shifting loads and the safety of drivers and passengers. Whether it is the prerogative of the chassis manufacturer or bodybuilder to " armour " the cab, can be left to them, so long as progress is reported in due course. The safety harness should soon be an item of standard equipment.
Glasgow. ARTHUR R. WILSON, M.I.R.T.E.
Why not Convert Railways to Roads?
wrm the ever-growing number of vehicles on the roads Tv and the prospect of twice as many in a few years, would it not be possible to convert the railways into roads? A start in this direction could be made with the railway from London to Sheffield, or Barnsley to Hull, each of which is duplicated.
It is my opinion that these could be made into highways which would prove so successful that they would lead to many more conversions. On them motor vehicles with a length of, say, 65 ft. could be employed and passenger trains could be replaced by buses such as the remarkable Super Golden Eagle operated by Continental Trailways of the U.S.A. Speeds of at least 60 m.p.h. would be attainable and permit great savings in time, money and accidents. Suitable vehicles would also be far superior in quietness and smooth running to obsolescent railway equipment.
York. A. I. WATKINSON.
[This idea is by no means new. It was suggested in The Commercial Motor at least 25 years ago and it was the subject of a recent conference. There are, of course, certain difficulties, such as comparatively low and long tunnels, insufficiently wide to accommodate the type of road which would be required. This problem of narrow width applies also to many lengths of line raised on embankments, passing through cuttings or in built-up areas. However, the advantages are presented that the land would be available with little or no additional cost, and the work on tunnels, bridges and other widenings might, in all, be less than that involved in driving a motorway through virgin country.—En.]
Molybdenum Disulphide • Not Harmful to Engines
THERE have recently been several statements in the A motoring Press suggesting that molybdenum disulphide additions to engine lubricating oils result in the formation of an abrasive oxide, with consequent excessive wear at the tops of the cylinders and particularly of exhaust valves. Following this allegation, the writer has had the engine of his M.G. Magnette—which has run for 36,000 miles lubricated since delivery with oil containing molybdenum disulphide additions in the generally recommended proportions—taken down and examined by an independent party.
The result of the examination has shown that the engine is in very good condition, with general wear less than usual. In particular the wear of the exhaust-valve stems varied from 0.0001 in. to 0.0002 in., whilst the guide weal was negligible.
Samples of whitish deposit were scraped from the exhaust valves and our own analysis has shown that these consisted essentially of lead compound (derived from the fuel), and the molybdenum content was under 0.01 per cent.
Leeds. G. J. VINEALL,
Technical Director, Rocol, Ltd.