OPINIONS FROM OTHERS.
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That One-sixth of a Penny.
The Editor, THE COMiVIERCIAL MOTOR.
 Sir,—The rejection of the Belfast Corporation
by-laws, which by-laws I was called in to oppose, has been noted in your coIninna. The Corporation, by agreement with the local bus owners and with the concurrence of the Government or Northern Ireland, upon the terms of which agreement :I was calledin to advise, will, from now forward, add very large numbers to its fleet of motorhusea and will order no more tramcars. Mr. Beckett, I agree, was on the other side.
I have at no time advocated an increase of passenger fares in Belfast by one-sixth of a penny or any oilier amount. No increase is needed.
The Belfast Corporation accounts provide, as do those of other tramway authorities; for both depreciatien and sinking funds. It is out of the depreciation fund that vehicles are purchased, alike in municipal or company practice. On top of such depreciation Belfast (and other towns) need one-sixth of a penny per passenger for sinking fund purposes (capital -extinction), which joint stock companies do not need. That is a clear and unassailable fact.
Various figures are on the proceedings of the Belfast Inquiry which were supplied by actuaries and accountants. I accepted the figure for a 15 years' re0e.mption scheme at 4i per cent. without checking it,. and Mr. Beckett is right that income tax had not been deducted. The effect of the necessary adjustment is to increase the redemption period from 15 years to practically 16 years.
Where tramrails have been taken up, the proceeds of sale on track account after abandonment of the tramway systems have usuallY been sufficient to cover the restoration of the roads. The sale of rails and setts have, in scme cases; produced a stinill`balance in hand. after paying for such restoration to the satisfaction of the local authorities.
It is true that the Belfast electrical engineer In his evidence stated that i4,000 Profit was made in 1971028 on the sale of electricity to the Tramways Committee. He also admitted, under cross-examination, that the tramway purchases were 22 per cent, of the whale of the units sold, that sales of the other 78 per cent, furnished very much higher rates of profit to the city, and that there was difficulty ahead in meeting the growing and more remunerative demand for electric supply for non-tramway.purposes. The sale of current to the Tramways Committee at specially low rates is a very doubtful advantage to Belfast ratepayers. They can well do without this favoured customer.—Yours E. S. SITRAPNELL-SMITII. Hound House, Shere.
The Torque Reaction of Six-wheelers.
The, Editor, THE COMMERCIAL MOTOR.
 Sir,--I notice that in a description of a rigidframe six-wheeler in the issue of The Commercial Motor for October 16th (page 269) it is stated, in the paragraph headed "The Be/Y-1e Driving Axles," that "the torque reactions are taken through the springs to the frame," and, further, " thia being of the familiar bogie type."
I venture to disagree with the first statement and propose to show that the driving torque reaction is taker. by the rearmost axle, and is,thus overloaded or laden two tons in excess of the forward driving axle when moving in a forward direction. Because of the importance of the subject, I suggest that publicity be ,given to this point in design and discussion be allowed in The Commercial Motor as to the pros and cons of
D42 "equal distribution of weight and torque reactions on the rear bogie wheels."
I am attaching a diagrammatic sketch showing that, contrary to the statement in the article, the driving torque reaction is taken by the rearmost axle when driving forward. I am also adding a few figures'that. will apply proportionately to any make employing a particular design of bogie that I have in mind.
In this case the engine develops 46 b.h.p. at 1,000 r.p.m.; therefore, the engine torque -.a. 2,900 inchlb. The overall gear ratio on lowest gear is 41.0 to 1; therefore, the total torque in the differential shafts equals 41.6 x 2,900, which equals 120,600 inch-lb. Hence, approximately, the driving torque reaction equals 120,000 inch-lb. or. low geaa.
A reference to the sketch will show that the centre point of the suspension being-a pivot there is a moment round it equal to the driving torque reaction—i.e.,
120,600 inch-lb., and this being resisted at a point hairspring centres away (24 inches) a pressure is caused . 120,600
at this point of —, Which equals 5,025 pe_a..e., 24 over 2 tons. (It must be noted that on top or direct gear this figure is over 1Q00 lb.) When in reverse a • still bigger load is possible, 6,200 lb. being a fair estimate. This, however, would be resisted by the forward driving axle and,in like manner, the reaction due to braking.
It will now be seen that the axles must be designed to take a load of I. ton (at least), in excess of that which is normally required. Why not, therefore, use torque rods and thus reduce the 5,025 lb.. to 118 lb. per axle, as the War Office design shows?
There is another important point. The tyre must•be a size larger than would be necessary if torque
rods were used to accommodate the unequal load on the axles.
All these points show the importance of the subject to owners of vehicles and points of interest to designers and manufacturers, so I suggest that this matter be discussed in the. columns. of The Commercial Motor, and would welcome eriUeism or acceptances of my arguments..—Your faithfully, C. R. CHURN. Reading.
British Worm-gearing on German Vehicles.
The Editor, Tnr COMMERCIAL MOTOR.
 Sir,—We have been interested to read the article on the Berlin Show in the issue of The Commercial Motor for November nth, and whilst we do not wish to appear unappreciative we think that you have not attached sufficient importance to a development which is rather a tribute to British industry. We refer to the application of the worm drive to a ntimber of existing vehicles; many of which are described in the issue mentioned. The most
significant point in this connection is that, with only one exception, every worm-driven German vehicle embodies worm gearing made in our works in Huddersfield..
Amongst the vehicles which have adopted worm drive transmission (and, incidentally, this is the first Year in which worm drive has been adopted on German vehicles) are the Aboag bus with Voran front-wheel drive and DRS worm gearing; the Selve six-wheel military vehicle, with DBS transmission; the Henschel worm-driven six-wheeler; the Durkopp six-wheeler and the Steyr light I.-/-ton truck. Although outside your particular sphere; it is worthy of note that worm drive has also been adopted on the 8-cylinder Audi car and the 8-cylinder Rohr.— Yours faithfully, DAVID BROWN AND SONS (HUDDERSFIELD), LTD. Huddersfield.
[The facts given here by the pioneer of worm drive for motor vehicles were not patent to us in our examination of the exhibits. We thank David Brown and Sons, Ltd., for the information and tender them our warmest congratulations and upon the compliment paid them by the German makers.— En., C.M.1 The Cost of Upkeep of Front-wheel-driven Vehicles.
The Editor, THE COMMERCIAL MOTOR.
 Sir,—The attention of the writer, has been drawn to the article on front-wheel-drive chassis in the issue of The Commercial Motor for October 23rd, which happened to coincide with our advertisement of a front-wheel-drive machine on the front cover of the journal. We must express our surprise at the statements contained therein as to the initial costs and upkeep of a front-wheel drive vehicle, and we feel that it must have been written without investigating the merits of our machine.
We supply a front-wheel-drive 3-ton machine for £595 the chassis and a front-wheel-drive 5-ton machine for £695 the chassis, from which it will be seen that the initial cost is not excessive.
Regarding the upkeep, we are quite willing to refer your readers to users of this type of machine, and we are certain that information is available which would have made you hesitate to express your views regarding maintenance costs.
At any time convenient we are prepared to give a demonstration run and any data that may be required on the subject.—Yours faithfully, , F. A. LE Voi, Director, LAM, INDUSTRIAL VEHICLES, LTD.
Giving Inventors a Better Chance.
The Editor, THE COMMERCIAL MOTOR.
 Sir,—In the issue of The Commercial Motor for October 23rd you are good enough to refer to one or two exhibits shown at the recent International Exhibition of Inventions. You refer to the proverbial "poor business capacity of inventors" and to "the meagre description attached to some exhibits."
Each inventor who exhibits at the above exhibition Is allowed a maximum free insertion of five lines (about 50 words) describing his exhibit, and any interested visitor to the exhibition is invited to ask for further particulars.
Many inventors who exhibit at the exhibition pay the exhibition fee of £1 by small instalments, and, therefore, you will readily realize that they cannot go to the expense of having leaflets printed.
This Institute does as much as possible to assist such inventors, and technical demonstrators are available in the hall to show the merits of any particular exhibit to an interested visitor.----Yours faithfully, G. DRURY COLEMAN, General Secretary, London, S.W.1. Institute of Patentees.