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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 type-written by preference. The right of abbreviation is reserved, and no responsibility for the views exPressed is accepted. In the case of experiences, names of towns or localities may be wahlteld.
Mileage and Speed Recorders.
The Editor, THE COMMERCIAL Molest:.
[1,274] Sir,—With reference to the letter j.No. 1,2681, signed "Motor-wagon Carrier," which appeared in THE COMMERCIAL MOTOR of the 8th inst., with regard to mileage and speed recorders for commercial vehicles, we would point out that we supply users of Albion vehicles with our now-well-known Albion mileage recorders, which act as a valuable check on working costs. This recorder is a robust engineering job, like the rest of the chassis, is capable of withstanding the vibrations of steel-tired vehicles, and is thoroughly reliable. It, however, is only suitable for Albion chassis, as we maintain that it is practically impossible to provide an adaptable instrument of this kind for fitting to a variety of makes of chassis. We consider a speedometer quite unnecessary on commercial machines, as it only acts as an incentive to drive at the maximum pos.sible speed. In any case, a commercial
vehicle should not be driven at any great speed. A mileage recorder is a comparatively-slow running instrument, and can, therefore, be suitably designed with a new to strength, but a speedometer is a high-speed instrument of complicated design—hence the failure of the latter to stand up to their work.--Yours faithfully, lasgow. Tie ALB/ON MOTOR Cu CO., LTD.
The Editor, THE COMMERCIAL MOTOR.
[1,275] Sir,—In your issue of the 8th inst., we notice a letter from " Motor-wagon Carrier," in which surprise is expressed that there is no speedometer and mileometer at present on the market capable of standing up under the stress and strain of heavy steel-tired vehicles, and your correspondent instances the facts that such delicatelyconstructed articles as steam-pressure gauges are able to stand up well on this class of vehicle, and that it ought to be possible satisfactorily to construct a speedometer. We have devoted considerable attention to this branch of the speedometer and mileometer business, and we fear that the difficulties in the way are not sufficiently appreciated by owners of these vehicles, or, indeed, by the manufacturers, or the latter would provide better oppor
tunities for the fitting of such devices. Stearn-pressure gauges, for instance, are mounted on boilers, which will naturally be sprung, and, so far as the instrument body itself is concerned, the same may apply to the speedometer, bat, at least in our experience, that part of the proposition
presents no difficulty. We have over and over again demonstrated that our instruments (the Jones speedometer) are absolutely capable of standing up well under the stress and strain of vehicles of the class we are dealing with. and to which your correspondent refers. Where the difficulty comes in, however, is in providing a suitable drive for the instrument which will stand up and give good service, because, of course, in driving from the road wheels, as is usually done, the fittings have necessarily to be attached below the springs, and consequently they are subject to excessive vibration and constant strain, which sooner or later will be hound to have disastrous effects, to say nothing of the liability to injury during cleaning, and in the locking of a car in steering, etc. We have continuously recommended that some provision be made for taking the drive of such instruments from the propeller, or cardan shaft, or chain sprockets, and we are able to guarantee satisfactory results where this is found possible, because in that case one has the •advantage of fitting above the springs, besides which the flexible drive to the instrument is better protected against liability to accident and wear and tear, to which it would otherwise be subject. It may interest the prospective buyers of such instruments to know that a considerable part of our instrument is now manufactured in this country.—Yours faithfully.
Markt and Co. (London), Ltd. (Dept. 3), F. E. TICKINSON, Manager. 6, City Road, Finsbury, E.C.
Weighbridges and Axle-weights.
The Editor, ME COALMERCIAL MOTOR.
[1,276] Sir.--On page 301 of your last issue, you publish two short contributed articles. May I have permission briefly to criticise a few po;nts in your two contributors' remarks?
First of all, with regard to the remarks as to the inefficiency of modern weighbridges. I am of the opinion that, as you evidently suggest in your editorial note appended, the writer is not quite clear as to the functions of a weighbridge. Theoretically, on a modern compensating weighbridge, it makes no difference on what part of the platform the weight is imposed, and, for this theory not to be substantially accurate in practice, there must be something seriously wrong with the weighbridge. That trouble of the writer's, with regard to the division of the lorry and its load by a line that is not straight, is a purelyimaginary one. As well might he try to argue that the gross registered weight of a man holding a dumb-bell at arm's length was not accurate, because the imposed weight was not all directly over his vertical axis. An efficient weighbridge will give correct axle-weights when each pair of wheels is separately and successively imposed on any part of the platform, providing that the bottom edges of all the wheels, on or off the platform, are in the same horizontal plane.
Your second contributor is evidently a humorist, and those two yarns of his are good enough to excuse their antiquity. Surely, Mr. Occasional Contributor, any wellfound machine is emergency-proof, that is, of course, if its brakes and other control gear are properly designed and effective in operation. (It is the driver that must be made emergency proof.) But this fact doss not necessitate that they be fool-proof. Conversely, an epicyclio gear is presumed to be fool-proof, but it is surely in no way superior in emergencies to the sliding gear, unless a man may be presumed to be more handy with his foot than with his hand. Perhaps this was in your contributor's mind, when he wrote his last sentence: "The fewer levers and pedals there are, the better it is: he (the driver) has only two hands and two feet, and he might want the feet to jump and save his life." Why should it save his life if his feet jumped ?—Yours faithfully,
" HIIMERICUS.' The Future Three-tonner.
The Editor, ME COMMERCIAL MOTOR.
{1,271] Sir,-1 had not intended to trouble you again on
this matter and must apologize sincerely for doing so, but I should like to say that I am very pleased to learn that
my humble remarks have aroused Mr. Aveling's interest.
He is kind enough to say that he would like to meet me; so far as I am concerned, personally, 1 should be de
lighted to meet him, but I think that perhaps he would find it better worth his while, from his point of view I mean, to call on the manufacturers of the two-ton lorry,
to which I referred in my previous letters. He could get them to show him the various improvements which have been made in the "steam-gas " vehicle. I feel sure that, as an engineer, he would see several things that would
interest him. The works of the manufacturers above
mentioned, are in what Londoners call " the North," and not so very far from Birmingham, so, if Mr. Aveling would really care to see this " steam-gas " lorry, I could easily drop a line to the makers, and I expect they would be
very pleased to show him the machine. and demonstrate its capabilities on some of the hilly roads, of which there are many within a few miles of the works.
Regarding Mr. Aveling's suggestions:— No. 1: re tare weight. I have not the figures for this item by me, but I will obtain them from the manufacturers, and forward them as soon as I get them.
No. 4: re area covered on one charge of fuel and water. Mr. Aveling says that on my figures (40-60 miles for the water, and 80-100 miles for the fuel), the internal-corn bustioned-engined vehicle shows better results than the steamer. 'Well, even so, are not these distances quite long enough for all practical purposes? Further, one should always remember that the steamer's fuel is only half the price of petrol.
No. 13: re instantaneous answer to the call for full power. Now here, if I may any so with the greatest respect, I am " up against " a criticism which ranks
among the most-fallacious, and, at the same time, the most difficult to combat, of all those which the supporters of "steam gas " have to meet. Very many people had rides on the early " steam-gas" vehicles. Very many of them had the same experiences as Mr. Aveling, viz., the car stopped on inclines, until sufficient steam was raised to enable it to proceed. Now these people are one and all firmly convinced that all steam vehicles aitrays stop on hills, and it is very hard to disabuse their minds of this fallacy. As a matter of fact this defect of the early steamer has been completely eradicated. The reasons why
the early steani cars stopped on hills, and required time to generate the power necessary, were four in riumber: the defective construction of the flash generator ; a. faulty method of supplying the generator with water and the burner with fuel; inefficient control of the pressure; no
means for regulating what is more important than the pressure on a "steam-gas" vehicle, viz., the temperature. The early" steam-gas " generator had no reserve at all. The flashiest of flash boilers, it emptied itself of steam,
with most-astonishing rapidity. The relief valve used, instead of mitigating this drawback, accentuated it. The method of feeding the generator was such, that, when a great quantity of water was required (as is the ease On. hills), the pumps were working at their slowest rate. Con
versely, when descending a long bank, the speed of the pumps was at its highest, just at the wrong moment. Not only was the temperature of the " steam gas " uncontrolled, but the driver was left completely in the dark as to what it might be. He had, in fact, to guess at it.
Now, at the present time, all these difficulties have been got over. The " steam-gas " generators (on the lines to
which I referred in my former letter), while capable of
delivering live "steam gas" at 950 deg. Fahr., and at pressures up to 1,000 lb. per square inch, are yet designed so as to possess a considerable reserve. Further, by a patented process of the makers, the tubes in these generators have been rendered very much more durable than was formerly the case.
A scientific system of feeding both generators and burners hits been devised, and water and fuel are supplied as required, in accordance with the demands of the engine. The patented relief valve of the makers, while relieving excess of pressure, yet maintains the reserve of the generator. I did not mean to suggest in my last letter, that, if Mr.
Aveling were to take a run on one of these lorries, a stop would be made purposely on the hills which I mentioned, in order to get. up steam, but merely because it seemed to me that one of the most difficult things, that a mechanically-driven vehicle can be asked to do, is to stop, and
then to restart, on a steep incline. If Mr. Aveling wished to travel straight over the hills in question, without stopping, I am certain that the above-mentioned lorries would take him up them at a much faster rate than. a petrol lorry of equal power. Regarding what Mr. Aveling says about the "steamgas " system's not being so simple as a petrol system, I
would just point out that there is no gearbox on a steamer; secondly, neither the generator, burner, condenser, nor feed-water heater are moving parts, and, in consequence, are not only cheap and simple to construct, but last a long time.
Thirdly, I might, with equal truth, retort, that, besides the petrol engine, there is a train of expensive,
sliding gears, which are moving parts, and which in heavy work wear out very quickly, there is a complicated and delicate electrical arrangement, involving more moving parts; there is an elaborate system of water cooling, a carburetter, and a handle to wind up the engine! No, the petrol engine is not so simple as "steam gas"
Regarding the White and Darracq-Serpollet systems, I may say I quite agree with Mr. Aveling. The system to which I refer is neither of those, nor is it that which Mr. Clarkson, of Chelmsford, has so persistently advocated, and which system is now embodied in a few London mote rbusee.
Regarding Mr. Aveling's last point, I must say I cannot agree with him here. Of course the " steam-gas"
vehicle will carry a heavy overload, and will keep up its usual speed, if driven hard. And of course, the petrol vehicle is incapable of doing this, as it is not flexible enough. But if the driver of the " steam-gas " vehicle is in his right senses, he will not force his machine unduly when she is carrrying a load greater than that for which she is designed. At the same time, I do not consider that
the petrol vehicle will stand up nearly as well as the steamer under overloading. In my opinion, the gears on the petrol car will give trouble, long before the steamer begins to want repairs. How long do the gears last On a London motorbus ?—Yours faithfully,
Richmond, Surrey.