OPINIONS FROM OTHERS.
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The Editor invites correspondence on all subjects connected with the use of commercial motors. Letters should be on one side ot the paper only and typewritten by preference. The right of abbreviation is reserved, and no responsibility for views expressed is accepted,
The Suspension of Six-wheeled Vehicles.
The Editor, THE COMMERCIAL MOTOR.
126011 Sir,—Mr. Baden Small(whose letter on this subject was published in the issue of The Commercial Motor for May 10th), must, I fear, be suffering from restricted vision when he states that it is impossible to secure an absolutely rigid chassis! I have been fortunate enough to see the marvellous performance of the Ford romping up hills and down dales in different countries, and if. Mr. Baden Small will stoop and examine this remarkable chassis he will find it absolutely rigid, owing to its transverse suspension.
As he entirely agrees with Mr. Whitehead's arguments (which were dogmatic—I think, without reason). perhaps he will be reasonable and tell the readers of The Commercial Motor why he thinks it impossible to secure an absolutely rigid chassis when equipped with transverse springs, .especially the type without axles. which gives independent wheel movement.
Having qualified to do fatigue duty during and after the war in most of the R.A.S.C. workshops within a radius of 100 miles or London, as well as overseas, I learned much about window-dressing and whitewash, and saw some of the exhaustive experimental work referred to by Mr. Baden Small, which impressed me, as a practical motor engineer, as being most exhaustive to the taxpayers' pocket—and without any return! The glowing accounts of the W.D. six-wheelers and other British machines of the type given by Mr. Baden Small do not impress me very much, because these vehicles are innovations and have not stood the test of time.
Until I have seen a certificate of performance from the R.A.C. on Porlock or other test hills or runs, I am content to be classed as a " Thomas " making misleading statements. A test run between two Ford corn c42 mercial vehicles and a W.D. six-wheeler carrying three tons, the Fords carrying 30 cwt. each, between Minehead and Lynton and back would be an interesting comparison. I am prepared to back the Fords on allround performance.
What would happen to the tyres of the six-wheelers on the sharp hair-pin bends encountered on Porlock? Would not the driving mechanism also be severely strained, owing to the front-wheel suspension?
The designers of the six-wheeled Paris buses, who have had many years' experience with six-wheelers, find it necessary to overcome this trouble by steering the back wheels as well as the front ones, although the buses operate only on broad, straight, flat bOulevards. In a recent paper, presented to the Institution of Mechanical Engineers, Capt. Kuhne, R.A.S.C., showed the back wheels of the W.D. six-wheeler standing in a grotesque 'position. Why did he not show the front wheels of the vehicle in the same position and let readers consider what would happen to the chassis and driving mechanism when the vehicle was crossing this obstruction at, say, 15 miles per hour?
There was another photograph with a chain mounte on the back wheels standing On a flat surface; wh, not have shown the chain on the wheels when the were in the pot-holes? These photographs inapresset me as Being scientific window-dressing. A transversel. sprung vehicle without axles, with independent whee movement, would negotiate the obstruction shown wit ease, without strain, on the chassis or drivi mechanism, and I invite Mr. Baden Small, Mr. Whit head, Capt. Kuhne, R.A.S.C., Colonel Niblett, or an other expert inside or outside of the War Office t refute this statement scientifically, which I can demonstrate to anyone with models.—Yours faithfully,
WILLIAM COCHRANE.
West Hampstead, London, N.W.6.
Tramcar versus Bus.
The Editor, THE COMMERCIAL MOTOR.
[2605] Sir,—As a reader both of The Comm' ercial Motor and The Tramway World, I see both sides of the omnibus-tramcar controversy and, as the position of the omnibuses is widely known, I would like to state the case for the tramways.
The bus has displaced the tramcar in many small towns where the volunie of traffic did not justify the outlay on reconstruction and it Is probable that several small systems will follow suit this year.
The case in large centres is entirely different, and although the large capacity of the six-wheeled bus has modified the position, the tramcar remains supreme for the heaviest traffic.
Many modern tramcars seat 80 to 90 passengers, and in some cases as many as 100, whilst the maximum capacity of a six-wheeled bus is about 68 to 72 passengers.
The tramcar is definitely cheaper to run; it uses a home-produced fuel; its tyre costs are negligible, compared with the bus; it has a longer useful life and comparative figures prove that it can be kept• in service for a longer period between overhauls than the omnibus.
In the last issue of The Tramway World it appears that tramway extensions are under construction, contemplated, or have just been opened in the following towns :—Edinburgh, Cardiff, Bradford, Burnley, Dublin, Liverpool, Nottingham, Sheffield and Yarmouth.
Glasgow has 350 new cars on order, Sheffield 50, Bolton 12, Moscow 400, whilst Leeds has just taken delivery of 200 new cars, and Croydon, West Ham. Bradford and Oldham all have new cars under construction. Most of these new cars are capable of a speed of from 20 m.p.h. to 25 m.p.h., and the new single-deck design evolved in Bradford is capable of a speed of 40 mph.
It may interest readers of The Commercial Motor
to know that tramcar designers, especially on the Continent, are closely following omnibus practice. Thus, "dead" axles with internal, fully floating driving shafts are being used in conjunction with differentials (to avoid squealing on curves). High-speed, lightweight motors are often employed, driving through propeller shafts to worm gear or double-reduction gear on the axles, and ball or roller bearings are used throughout. Further, by adopting omnibus methods of bodybuilding, as much as four tons of deadweight has been saved.
A. recent deputation of traffic experts from Berlin reported that one glance at London's tangle of omnibuses had cured them of wishing to extend the omnibus system in Berlin. This may be rather a wild statement, but the leader of the deputation, Herr Grothweil, made it clear that in Berlin they did not regard the omnibus as a substitute for the tramcar.
The general strike cost the London tramways £226,000, and but for this there is every reason to believe that the deficit last year would have been very small. The provision of cars with upholstered crossseats in the lower saloon has been very successful, and the receipts have this year exceeded by about 12,000 a week those for the corresponding weeks last year. Services have also been speeded up and the average speed, including stops, is now just under 10 m.p.h.—a very good performance.
In the United. States many tramways have now been wholly or partly relieved of the unfair road-paving burdens, and there are signs that this may also be done in this country.
Finally, we may say that although the bus has resuited in the extinction of several small tramways (operating obsolete stock for the most part), the spur of competition has led to the evolution of new Ideas and new designs which are enabling the tramcar to maintain its position in the sphere of modern trans port.—Yours faithfully, • A. G. FITZGERALD. London.