Answers to Queries.
Page 19
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Budget Taxes.
[2967] (Wales).—The new rates in the Budget will not apply to chars-a-bancs,, or taxicabs, or lorries. Presumably the clause in the 1909-1910 Finance Act, under which any increase of licence duties is not to alter the rating for hackney carriages, will remain in force.
Hiring of Heavy Motors for Munitions.
[2969] (Itiverside).—The quickest method for you to i adopt s to get in touch with any manager of munition works which is reasonably near to your premises. Failing that an application to the Transport Department of the Ministry of Munitions, Whitehall Court, London, S.W., might bring you in touch with the necessary requirements.
Carburetter Trouble.
[2969] (Kent).—We are afraid it is impossible to advise you from your letter without inspecting the machine. At the moment we have no engineers available-who are not fully occupied with inspection duties—and will be for some time to come.
Any good garage should be able to advise you on the points you raise. with regard to your carburetter.
Engine Knocks with Paraffin Mixture.
[2970] (Ireland)—The use of paraffin in the manner you describe should not, under ordinary circumstances, have a tendency to make the engine knock. Possibly the fault lies in other directions.
Have you inspected the timing of the magneto on your engine, and is it correctly set? With the ignition lever fully advanced, the contact screws on the magneto should separate when the piston is half an inch from its topmost position on the compression stroke.
Licences for Public-service Vehicles.
[2071] (Licence).—We have had a search made with regard to any records in THE COMMERCIAL MOTOR of licences being refused for public-service stage carriages once they had been granted, but we cannot trace any record of such action within the last few years.
At a much earlier date, however, a classic instance of the refusal of licences after •once they had been granted was that of Manchester ; Brighton and Bir-. mingham were, we recall, instances where renewals were only granted under limited conditions.
Steel for General Repairs.
[2972] (Bournemouth).—We think you would be well advised to do as your steel merchants recommend, i.e., to purchase the 30-ton mild steel for general purposes, and the chrome vanadium steel for the replacement of the parts subjected to high stress. We do not think it necessary that you should get into correspondence with another firm, unless for the purpose of obtaining competitive prices. In the event of your doing so, you will, of course, have to be careful to specify the steel exactly as it is offered to you by your present contractors.
Which of Three Stadion Models?
[2973] (Sunshine).—We have personally examined each of the three models of the Belden chassis.
We should say that for general all-round purposes, perhaps the internal gear would be a good machine to handle for demonstration purposes, owing to the fact that its first cost is so much lower (230) than the worm.
Between the chain-driven and the internal geardriven there is little to chooseS an advantage of the internal-gear model is that aft the mechanism is enclosed, but if you require chassis for passenger work, you might find that the more silent running of the worm-driven chassis Would be an advantage. Governor Patents.
[2974] (Patentee).—We are returning the drawing and description of your patent governor. We have considered this very carefully and mast congratulate you on the •idea, which is a very ingenious one. We do not remember having seen it carried out pre-. viously.
You will find several practical difficulties in the way of adapting this device to existing engines; it should, however, be fairly easy to arrange for it on an. entirely new chassis' and it should be very little more expensive than the governor as it is •ordinarily arranged Whether you should obtain patents will depend -to a certain extent on your financial arrangements. We think that we informed you in a previous letter that a complete patent would probably cost you from 10 to 12 guineas, and that, of course, would only be the beginning of the very considerable expense which would have to be met in experimentation, and even then it is possible that you will find that something of the sort has been tried before.
Agricultural Tractor Design.
[2975] (Salop).—It is practically impossible to give the information for which you ask so that it will be applicable to all conditions and all roads.
In the circumstances, perhaps the maximum drawbar pull would be about one-third of the load on the rear wheels. For agricultural work on dry, rough soil, you would probably be able to reckon on this amount, but on grass and in mud or slime, or even on wet soil, this figure would have to be very considerably reduced ; as you know yourself probably, a steam tractor with straked wheels occasionally fails to obtain a grip on wet setts. If you take it that, in such a case, the wagon is attempting to pull a trailer which with load weighs eight tons, the road resistance on setts will be about 90 lb. per ton, and it should be noted that the draw-bar pull needed, but not available owing to lack a grip on the road, is very little more than 700 lb. It is very likely, that, when in running order, the weight on the wheels of such a tractor would be about four or five tons ; this means that the draw-bar pull available is less than one-sixteenth of the load on the rear wheels.
With the figures varying between such wide limits, you will understand that it is difficult, as stated in the opening paragraph of this letter, to give any definite basis for calculation. The above information, however, may help you. The diameter of the wheel has an indirect effect, though the reasons for this are somewhat complicated and cannot be dealt with in a letter. As a general rule, it may be stated that the greater the diameter and greater the width of the tread, then the better should be the draw-bar pull for agricultural work. We are afraid that we cannot at the moment call to mind any handbook which deals with this matter, and, with regard to your postscript, it is very unlikely that a. controlled firm will be allowed to experiment at the present time.