QUERIES
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WHAT SHOULD BE THE COST OF INSURANCE?
[5183] Referring to certain correspondence which you have published in connection with the cost of insuring commercial vehicles. The tariff rates for a 15`.1ton vehicle valued at about 21,800 and operated under an A licence, is actually over 200 per cent. more than S.T.R. allows in your Operating Costs Tables, and that
for a good risk. W. R. JAcKsoN, for The Warpool Transport Co.
London, N.W.1.
[The difficulty is that there is a considerable variation indeed in rates of insurance, especially if, as I think should be, non-tariff as well as -tariff rates be taken into consideration. I have found that many hauliers seem to be able to come to favourable terms with insurance companies and Mr. Jackson will be surprised to learn that the figures in the Tables, which are meant to apply only to ancillary users, have actually been challenged by hauliers as being excessive. It is not correct to state that no provision is made for this under Hauliers' Charges. I include the extra amount for insurance as part of what I call the haulage contractor's business . charges .—S.T R .1 DO BRAKING FIGURES CONTRADICT FRICTION RULE?
[5184] I note with interest your remarks on friction
contained in The Commercial Motor of August 27, which I think boil down to the fact that "friction is inversely proportional to speed." This, when applied to braking systems, means that the brake efficiency falls as the road speed increases, and, of course, vice versa.
A contradiction of the above, however, can be found if anybody cares to convert your usual road-test braking graphs into terms of brake efficiency per cent. The Daimler double-deck bus, which was tested recently, proves itself to be a good example. From your graph I have obtained the following figures : From 10 m.p.h. an efficiency of 24 per cent.; from 20 m.p.h., 40 per cent.; from 30 m.p.h., 52 per cent. Perhaps somebody will, elucidate this problem.
Belfast. H. A. KAY.
[You raise an extremely interesting point, in which are involved certain issues that are not yet fully understood. In the first place, it is not only the friction between drum and shoe-facings that has to be considered, but also that between tyre and road. There is little doubt that the former is inversely proportional to speed, but in the case of the latter: the coefficient is highest at average speed and diminishes in value at both lower and higher speeds. We would draw your attention to an article entitled "Better Fundamental Knowledge Required for Brake Improvement" whiN appeared in The Commercial Motor OR May 21 last. It dealt with the views of Dr. Steinitz—a well-known authority—on this very question. If the speed of retardation be limited by the mixture of sliding and gripping friction between tyre and road, which is presumably the case, then it is clearly incorrect to base braking efficiencies on the first theory,
particularly as it is impossible accurately to substitute a definite value for " average speed." In the second place, the question of time lag arises, and we think this alone might largely account for the discrepancy to which you draw attention. The Daimler has the Dewandre triple-vacuum-servo system, but it. is riot only the small lag between pedal and braking that one must consider, although, this cannot be ignored; there is also the lag between the idea of braking (on the part of the driver) and the commencement of movement. We can assume that the sum of these time periods is the same, whatever the speed, but the time taken to come to rest varies in some relation to the speed. The figures published in our graph include this time lag, the distance being measured from the word " go." Therefore, before calculating true efficiency percentages, the distances travelled during the lag period (and these do vary with the speed, to some extent lessening the error) must be subtracted from the total distance. If this could be done with precision—an impracticable task—we think the results would more nearly accord with the original rule,—En.]
WHERE DOES THE RESPONSIBILITY FOR DAMAGED LOADS LIE?
[51851 We shall appreciate your views on the following:— A load of hops carried to a London market arrived at its destination in perfect condition. The foreman in charge of the warehouse to which this was to be delivered instructed the driver to remove the sheets which covered the load, and to draw under the crane for unloading.
As you are probably aware, a good many warehouses have covered accommodation for unloading, hut in this case no cover was available and while the lorry was under the crane, but before the hops were removed, a sudden shower of rain came on, and they became damp.
The farmer, for whom the hops were carried states that he may ha.ve to make a claim against us for the damage which took place, and although he claims for no definite amount, he states that an account for the same may be rendered when the hops have been examined at some future date.
Our repudiation of this claim is based on these points : (1) that hops should be unloaded under cover, (2) as the sheets were removed on the instructions of the donsignee's staff.he is responsible, (3) that, as we carry goods under an A licence and not as common carriers, we are not liable.
There were several lorries in the same street at that time which must also have been affected by the above mentioned shower. A LICENCE. London, SEE
[We have carefully considered the queries in your letter and we concur in your views. Any claim the farmer might have for damage to the hops will lie against the proprietors of the market—En.)
MR. SHAW'S TESTS WITH SPRAYED-STEEL AND HARDENED SHAFTS.
[51861 I feel that the short report of my paper before the Association of Metal Sprayers which appeared in
The Commercial Motor of October 29, may have misled your readers. It may have given the impression that in my tests the shafts running in white metal after zolloidal-graphited lubrication seized in about three hours, whereas the sprayed steel /an for 22?‘ hours.
Actually this is not so, for tests were made on, hardened steel and sprayed steel running in white metal with straight mineral and colloidal-graphited oils, Running at a speed of 261 ft. per min. with a load of 300 lb., the following were the running times after the oil supply had been cut off for the different combinations:—
1354 Hardened • steel in white metal with plain oil seized after three hours.
Hardened steel in white metal with colloidal-graphited oil still running after 181 hours, when the test was stopped.
Sprayed steel in white metal with plain oil se4ed after 22ihours.
Sprayed steel in white metal with colloidal-graphited oil still running after 190 hours, when the test was stopped. HARRY' SHAW. Rochda]e.
THE TRANSPORT ADVISORY COUNCIL'S REPORT.
[5187] You did well, in your leader of October 22, to draw attention to the question of the railways being able to wreck the proposed road-rates structure, for therein lies the "fly in the ointment." It cannot be too strongly emphasized that this could be strangled unless protected by the Government.
Beware of railway plausibility; it has already
worked "Miracles," i.e. (1) obtained road powers for them, (2) won the affections of the Salter Committee, (3) resulted in the Road and Rail' Act, 1933, and it can easily prove fatal 'to road transport in this-'case. The fact to be constantly kept in mind is that the railways have not withdrawn their declared intention of a monopoly, and they are already in possession of sufficient weapons almost to secure their coveted monopoly.
As already stated, the readiness of the railways to agree to a road-rates structure is an . ill omen rather than a good one. At present they cannot kill a structure which does not exist, although they can inflict wounds ;' besides, under present conditions, many hauliers can and do commit rate suicide. It is excellent t.rategy for the railways to cease fire on a conspicuous front and -concentrate on flanking.
AdmittedlY in theory, the railway goods-train rates
are public property, but in practice they are either in the "strong-room" of the railway stations, which only the xey of knowledge and wisdom can open, or. in the "offing." Until recently, the passenger-train rates and charges (other than passenger fares and ordinary parcels traffic) were a closely guarded secret. The book (Coaching Arrangements Book) as labelled ." Private. For the information of company's servants only,!' but, fortunately, memory served me well when, during the war, I was appointed to despatch about 100 aeroplanes per week.
Believe it or not, this "C.A.B." knowledge not only enabled me to reduce the passenger-train charge previously made by the railways from £25 to 1.2 10s., but to rectify the startling anomaly that the cost -of conveying an aeroplane by goods train was much, even then, in excess of that by passenger train.
WALTER GAMMONS, Managing Director. (For Walter Gammons, Ltd.) London, E.C.2.
A SUGGESTION FOR MR. D. L. CLARKE.
[51.881 I have read with considerable interest in your issue dated October 29 the article "From Competition to Monopoly," written by Mr. D. L. Clarke, and, in view of the recent report on rates and services issued by the Transport Advisory Council, I am sure that it would prove to be of great value to the industry if Mr. Clarke could -set out in a future. article the schedules of rates obtaining to-day for the haulage of goods in
Northern Ireland. A. F. SHAW, Director.
(For Merton Engineering Co..,.' Ltd.)