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17th January 1907
Page 19
Page 19, 17th January 1907 — Correspondence.
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Which of the following most accurately describes the problem?

The Question of Trailer Brakes.


Sir :—Can you explain, why the authorities are strict on the question of motor wagon trailer brakes, yet allow threshing machines, unprovided with brakes, to be hauled by traction engines? Surely one is not more necessary than the other ?--Yours faithfully, ROBERT REED. Langbaurgh Mill, Yam,

January 14th, 1907.

[We are unaware of any requirement as to fitting brakes to trailers of traction engines. The Legislature, probably, holds that the greater speed of heavy motorcars renders more care necessary. At the same time, having regard to the greater weight of traction engines and their trucks, we do not doubt that any new Act affecting this traffic will make provision for brake fittings in such cases.ED.]

Racing Motorbuses.


Sir :—Referring to Mr. Campbell-Swinton's remarks, regarding the racing of motorbuses, in the issue for last week of "THE COMMERCIAL MOTOR," I think sporting instincts have less to do with the fast driving of cars, than the fact that a great many companies pay by the journey, and, in order to get a fair day's pay, the driver has to get over the road as fast as traffic and other circumstances permit. I consider that this method of payment is not the most profitable to the owners, on account of the fares that are missed through hurrying over the journey; the driver is hardly likely to nurse his car when it means a dead loss to him at the day's end. The effect of a little nursing, on a vehicle which is stopping and starting continually, would be a reduction in. the cost of maintenance that would, perhaps, surprise the heads of a motorbus concern, if they could only know it. As regardsa remark, in the previous number of" THE COMMERCIAL MOTOR," made by MT. Beaumont, I think, that the public do not want high speeds, I find that the public, as a whole, is always in haste to get to its destination, and, the faster the car travels, the better the passengers are pleased.—Yours faithfully, January 12th, 1907. " SALMON PASTURES."

The Hitchon Gear.


Sir :—With reference to Mr. Hitchon's letter in your last number, I am surprised that he has not heard that the Lancashire Steam Motor Company fitted a free-wheel, almost identical with the Hitchon type, in their gear box, three years ago. This had the same arrangement of two gears in mesh at once, but proved a failure, as centrifugal force, alone, will prevent the rollers from dropping into position; a second cause of the clutch not gripping, immediately, is the use of viscous oil (a necessity), which makes the rollers sticky and holds them out of position. Mr. Hitchon's explanation of a start on a gradient is hardly feasible with a heavy vehicle. He states that "all the driver has to do is to let the engine clutch in and withdraw the top speed gear as the vehicle begins to move." Now, if it is possible to get the vehicle moving in the top gear, on so stiff a gradient and fully loaded, why have a gear box at all? I may mention that there is another factor against this type of gear, and that is the great bursting strain created by the rollers, which act in a similar manner to so many wedges, eventually breaking the outer ring of the free-wheel clutch. This necessitates a massive outer ring, and, therefore, a heavy gear box, and, also, heavy gears to withstand the shocks, caused by the free-wheel gripping.

It has, frequently, been found that inventions which appear to possess great advantages, in the model, fail, conspicuously, when subjected to the trying conditions of commercial vehicle work. In conclusion, I should like to mention the striking contrast between the above gear, formerly used by the Lancashire Company, with the present light but, yet, efficient " Panhard "-type gear box used by that corn pany.---Yours faithfully, M. SUTTON. 3, Market Parade, East Finchley, N., January 12th, 1907.

Multiple-disc Clutches.


Sir : -I notice that Mr. Douglas Mackenzie, in the course of his excellent paper, read before the Society of Motor Omnibus Engineers, stated that only two forms of clutch were in use on London buses, viz., the leather-faced cone and the metal cone. I would remind Mr. Mackenzie that the Thornycroft buses on the " Vanguard " No. i Service are fitted with multiple-disc clutches of the Hele-Shaw pattern. I believe, also, that the Thornycroft, Arrol-Johnston, and Fiat companies have been using disc clutches for a long Lime past, and have found them very satisfactory.

I think it highly probable that the primitive cone clutch will, shortly, disappear in heavy vehicle work, in view of the superiority of the disc clutch in every respeet—except, perhaps, in first cost.Yours faithfully, January t4th, 19o7. HAROLD H. CARTER.

The Application of Forced Lubrication.


Sir :—T was much interested in the article and illustrations, published on pages 392 to 394 of your issue of the 3rd instant, for I was under the impression that forced lubrication dated back very much further than is stated by Mr. Douglas Mackenzie. Your own foot-note points out that the Arrol-Johnston engine employed this means of securing efficient lubrication as far back as the year 1896, and I venture to think that, after the subject is ventilated in your columns, some of your engineering readers will be able to furnish particulars of other instances where crankshafts have been adapted in a manner very similar to that which has now been adopted by Mr. Bell. On the score of " honour to whom honour is due," I trust you will find space to afford opportunity for the communication of other views on this subject, and, more particularly, because the general adoption of forced lubrication appears to be more

than probable.—Yours faithfully, R. J. WILLIAMS.

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 type-written by preference. The right of abbreviation is reserved, and no resPonsibility for the views expressed is accepted,

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