OPINIONS FROM OTHERS.
Page 24
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The Editor invites correspondence on all subjects connected with the use of commercial motors. Letters should be on one side of the paper only and typewritten by preference, The right of abbreviation is reserved, and no responsibility for views =pressed is accepted.
Return Loads.
The Editor, THE COMMERCIAL MOTOR.
[2193] Sir,—I append here a. slip (the wording of which is as follows):— Deliveries periodically by our own motor vans within 100 miles of London—FREE.
Return loads accepted at half rail rates. Particulars on application, -which I received this morning attached to a circular, advertising the money-saving qualities of motor lorry supplies manufactured by a well-known firm. You will observe, no doubt,, that they inform all and sundry that they will fetch back by their delivery lorries any loads at half railway rates, from 'any town within 100 miles of London.
Is it fair to assume that the genius who drew up the circular also composed the slip, so that on the one hand he generously offers to save us money by selling us oils, etc., at cheaper rates, and on the other blatantly shouts from the house taps that he will do his best to make us drop our ratesindiscriminately to anything in the margin of 50 per cent, below railway rates?
I would like to take up the challenge of "Return loads accepted at half railway rates" and introduce our friend to a colliery owner' in the Forest of Dean. —Yours faithfully, per pro. DICK, JACKSON AND CO., LTD , London. C. ROBERT GRAY.
Suggested Improvements in Commercial Vehicle Design.
The Editor, THE COMMERCIAL MOTOR.
[2194] Sir,—As an observer of comMercial vehicle design, it appears to me that this type of vehicle is developed mainly from pleasure-car design, the latter being usually about five years or so ahead. Is this really beneficial to the evolution of the type or to the user ?
I have in mind a two-stroke engine of robust proportions, running at, say, 450 r.p.m. -without crankchamber compression, fitted with a, mechanical lubrication system, in a chassis of strong design—not necessarily pressed steel, preferably ash with flitchplates. Owing to the simplicity, few working parts, and to developing its power at slow speed, wear and tear would not be so great as with the modern highspeed engine, where perfect lubrication must function regularly to ensure long life to bearings, pistons, etc. With these engines, regrinding of the cylinder bores is far too frequently necessary, and burnt valve and big-end failures are not unknown.
It will be remembered by your readers what excellent work has been done in the past by the two,eylinder Albion machine here and in the Colonies, driven by absolutely unmechanical individuals, which I think bears out my point—that a slow-speed engine 13,1.0 is the. ideal for commercial work—and the development of a two-stroke engine would overcome, to a great extent, the noise question when excessive-wear takes place. Of course, there are difficulties to be overcome—petrol consumption, four-stroking when running light, etc.—but the development of the Leyland " Trojan" shows clearly that designers are fully alive to the possibilities of the type.
I have sketched ouf a rough design embodying the above features, and should be interested to hear the opinions of some of your readers.—Yours faithfully, Brondesbury. , FREDERICK H. HAMBURG.
Low-pressure Tyres:
The Editor, THE COMMERCIAL MOTOR.
[2195] Sir,—Many letters and articles are appear
ing on the above subject, but if you will read the following letter you will see that I had already -discovered in 1908 that reduced tyre pressure could increase comfort and lengthen the life of my tyres:—
,
"Increased.Mileage on Pneumatic Tyres with
Decreased Pressure.
" The Editor "As you are probably aware, I have made very considerable experiments to find out, firstly, whether reduced pressure decreases the speed of the vehicle fitted with pneumatic tyres or not; secondly, whether decreased pressure. decreases or increases the life of the tyre. The first Series of tests proved that reduction of pressure in the, tyres makes practically no difference in speed.
" The second series of tests proved that you cart use your tyres with less pressure than was commonly thought, and, therefore, the whole car rides more easily and smoothly, and at the same time the tyres actually last longer. The tests have all been carried out on the road on my own sixcylinder Napier. " The weight of the car complete, as I generally drive it, was a shade under 35 cwt. The replt was that, with 60 lb. pressure in the front tyres, 880 mm. by 120 ram.; they ran 88 per cent. farther than when the pressure was kept at 70 lb. to the. square inch, arid when the pressure of the back tyres, 895 mm. by 135 mm,, was reduced from 85 lb. to 70 lb., I got an increased mileage of 49.9 per cent. It is, therefore, clearly proved that reduced pressure means greater comfort on a, motorcar, and less expense in tyre bills_
"I am now carrying out experiments with still lower pressures, but owing to the distance one has to run, it takes a considerable time to obtain results.—Yours truly, S. F. EDGE. " London. 9th July, 1908."
Since finding this out I have always run my tyres at considerably lower pressure than was normal or recommended by the tyre manufacturers.—Yours faithfully, S. F. EDGE.