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OPINIONS FROM OTHERS.

24th April 1928, Page 71
24th April 1928
Page 71
Page 72
Page 71, 24th April 1928 — OPINIONS FROM OTHERS.
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Keywords : British Brands

The Editor invitee correspondence on all subjects connected with the use of commercial motors. Letters should be on one side of the paper only and, preferably, typewritten. The right of abbreviation is reserved, and no responsibility for views expressed is accepted.

The Continued Attack on Six-wheeler& The Editor, THE COMMERCIAL MOTOR.

[2668] Sir,—Out of many commercial vehicle manufacturers in this country, for some reason best known to themselves, the Leyland Company have thought fit persistently to attack the six-wheeled vehicle. When this attack first started, we thought fit to ignore it and to regard it as a passing phase, but, as the attacks are continuing to crop up in different forms, we feel it is incumtient on us, as one of the pioneer manufacturers of six-wheeled vehicles, to recount the facts.

Some twelve or fifteen months ago, there was circulated amongst a large number of the important users a mysterious anonymous list of the alleged "Disadvantages of rigid-frame six-wheeler chassis." The Editor of The Commercial Motor in an article in the issue for February 22nd, 1927, replied to the alleged " Disadvantages " (a copy of the reprint of which we shall be pleased to supply to anyone on . application), and in the course of this article said that "the concern responsible for this circular (the list of ' Disadvantages ') may be considered not to be impartial or unprejudiced." To this article the Leyland Co. made no reply.

On December 14th, 1927, when Mr. G. J. Rackham, the chief engineer of the Leyland Co., read a paper before the I.A.E. at Manchester on "Modern Bus Design," he devoted a section to an attack on six-wheeled vehicles, part of which stated that "the six-wheeled bus was introduced in America some four years ago" --(actually six or seven years)—"was adopted by many of the leading manufacturers "—(seriously, only by one)--" as has been done in England ; many hurried and half-thought-out designs were put on the market and then hurriedly dropped." (We do not know of one in England and the Safeway Six Wheel Co., of America, are producing more to-day than ever !) "At the present moment the six-wheeled bus is ' dead ' in America and the author quite anticipates that it will

'dead' here within a year or so, except, possibly, for a few very large double-deckers."

In a letter which the writer has received from the Safeway Six Wheel Co., of Philadelphia, informing him that they had recently executed an order for 62 sixwheeled buses for New York City, they said : "Incidentally, it is quite encouraging to all six-wheel manufacturers to know that the largest city in America has given the first order since awarding the franchise for a solid fleet of six-wheel design. I think this will do more than anything to satisfy the gentlemen that the criticism of six-wheel construction and design comes more from manufacturers of four-wheel vehicles than from operators of the six-wheel type."

The reply of the Editor of The Commercial Molar to Mr. Rackham's paper and the views of the British manufacturers interested in six-wheelers were published on December 27th, 1927, under the heading of "A Curious Attack on Six-wheelers" {a reprint of which also we shall be pleased to supply to anyone on application), and in the course of the article The Commercial Motor stated : "We do not agree with Mr. Rackham's attempt to claim for four-wheel construction the merit earned by the six-wheeler." To this article the Leyland Co. again made no reply,

The writer, who attended the Manchester meeting, criticised this attack, to which Mr. Rackham did not reply, but Mr. Liardet, the general manager of Leylands, stated that his company was not against the sixwheeled vehicle and that the expression of opinion of their chief engineer must not be taken as the opinions of the directorate.

In spite of these remarks, it is interesting to note that the chairman of the Leyland-Co., at its annual meeting—whose speech was widely advertised—in reference to three-axle machines (i.e., six-wheelers), is reported as stating: "On ordinary roads and for the carrying capacity which is generally demanded both for passenger and goods work, your directors do not believe this type of vehicle has any advantages, but, on the contrary, it has many disadvantages. It is heavier, more costly to produce and more expensive in operation and maintenance."

Having read, and possibly re-read, the above facts, together with the reprints of the articles referred to. your readers will form their own conclusions as to the merits of six-wheeled vehicles and the reason for the Leyland Co.'s persistent attack on this type of vehicle. —Yours faithfully, For Guy Motors, Ltd., SYDNEY Guy, Managing Director. .Wolverhampton.

The Humfrey-Sandberg Free-wheel Clutch.

The Editor, -THE COMMERCIAL MOTOR.

[2669] Sir,—In the r6sume of our patent specification No. 286389, published in the issue of The Commercial Motor for April 10th, your contributor expresses surprise that, in view of the fact that gradual take-up of the engine is one of the main features of the Humfrey-Sandberg free-wheel device, in one arrangement ratchet-shaped dog teeth are mentioned as a means of obtaining bidirectional drive.

The gradual slipping engagement which can be obtained with a properly controlled Humfrey-Sandberg clutch, used as a means for reverse drive, certainly gives the most perfect form of bidirectional coupling and will undoubtedly be used in all cases where the inertias are large, such as with commercial vehicles. In small cars, however, where the Inertias of the gearbox parts are small, sudden engagement of the reverse drive may be igtade without undue shock, provided the engine itself bdisolated from the gearbox by the main clutch.

Your contributor omits to mention that, in the scheme embodying a reverse ratchet-type dog clutch, a special interlocking arrangement is described which prevents the engagement of the dog teeth until the main clutch pedal is depressed. With stich interlock, the inertia of ttai gearbox shaft only has to be overcome by the ratchet teeth and the engine can be picked up, even if stopped, by judicious use of the main clutch. The scheme, however, is only proposed as an inexpensive unit suitable for small mass-production light cars.

In the scheme illustrated in your article a light form' of Humfrey-Sandberg clutch is used purely for smooth pick up of the engine and for taking the reverse drive of the engine when descending hills. For driving the vehicle in reverse the dogs shown on the left of the drawing are engaged. At any time during running, however, the reverse Humfrey-Sandberg clutch can be used for synchronizing the speed of gearbox shaft and propeller shaft and the positive dog teeth can then be brought into engagement without shock.—Yours faithfully, For Humfrey-Sandberg Co., Ltd.,

London. W. SEMPILL, Director.

A Light Wheel for Semi-pneumatic Air-core Tyres.

The Editor, THE COMMERCIAL MOTOR.

[26701 Sir,—We have read with interest a short notice in the issue of The Commercial Motor for February 21st concerning our patent No. 276,304, in which the main feature of our special light wheel was brought t6 notice. As this wheel has been specially designed to meet the needs of the motor trade, we feel it is necessary to add a little further information upon this subject.

The chief advantage of our patent wheel is its lightness, making possible the use of air-core tyres on medium-weight lorries, without increasing the unsprung weight of the vehicle, which factor is obviously of the highest importance to the life of the engine and differential gears, and to the general service of the vehicle.

. In the wheels covered by our patent, the rim of the ordinary wheels and the steel band of the ordinary solid or air-core tyres are replaced by a single steel band on which the rubber band is directly vulcanized. In order to give an approximate idea of the weightsaving which is obtained with our patent wheels, we will say that whilst the weight of an ordinary wheel fitted with air-core tyres, size 670 mm. by 175 mm, is 264 lb., that of our patent wheels with the same tyres is 176 lb. This latter weight compares very favourably with the weight of the corresponding size of highpressure pneumatic tyres (895 mm. by 135 mm.) fitted to disc wheels, which is about 172 lb.

It is evident, therefore, that this fact eliminates, the above-mentioned difficulty and makes it possible to secure all the advantages of economy and safety which can be obtained from the air-core tyres as compared with pneumatics without an increase of weight. • It is also interesting to note that with this new type of air-core-tyred wheels speeds of 38 m.p.h. have been recorded without affecting in any way the attachment of the rim to the wheel disc, or that of the wheel disc to the hub.It will, of course, be understood that the above-mentioned speed is not generally practised, but we give this data in order to indicate the durability of our light wheels, a large number of which have been in actual use for a considerable period.

• We have not overlooked the trouble which disc wheels might show through insufficient strength, and our first care has been that of reinforcing the wheel within the weight limits desired. We can assure you that, although we have a few thousands of these wheels in circulation, some of which are running for highspeed service, no complaints have yet been recorded.—

Yours faithfully, PIRELLI, LTD. London, E.C.4.

The Suggested Petrol Tax.

The Editor, THE COMMERCIAL illgrott.

[2671] Sir,—I hope they will get this through. The tax is a burden and a handicap and out of all proportion to the mileake covered and tonnage carried by thousands of little people. No doubt there will be grumbles, but the complaints will only be from people who are getting a lot for their money under the present system of taxation on unladen weight or on seating capacity. The tax on petrol would adjust this unequal charge and spread the burden more upon the shoulders able to bear it, and it would give us a free hand to use stronger vehicles, which would be more suitable for our work, thus stimulating business.—Yours faithfully,

London, N.W.3. A COMMERCIAL USER.

[The columns of The Commercial Motor are always available to our readers for the expression of their views upon matters of importance concerning road transport. Letters should be addressed to the Editor of The Commercial Motor, 5-15, Rosebery Avenue, London, RCA.]


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