OPINIONS FROM OTHERS.
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The Bditor invites correspondence on ail subjects connected with the use of commercial motors. Letters should be on one Aide of the paper only and typewritten by preference. The right of abbreviation is reserved, and no responsibility for views expressed is accepted.
Two-tonner Petrol Consumption.
The Editor, THE COMMERCIAL MOTOR.
[1952] Sire—I have read with interest the letters of your contributor " The Sketch" and your correspondent Mr. A. F. P. Phillips on the above matter, and I am exceedingly pleased to see the reply of Mr. Phillips with regard to the mileage consumption of the, two-ten Republic track. I.have been, for the past two years, in daily touch with the owners of between 40 and 50 Republics, and I have yet to learn of a single complaint with regard to excessive petrol consumption. I can put ". The Skotch " in touch with no fewer than a dozen owners of the two-ton model who are daily averaging 16 and 17 miles to the gallon,. andthis with vehicles operating in the county of Durham, which is noted for its bad roads and its hilly nature.
Mr. Phillips has very properly pointed out that petrol consumption rnust vary according to the work done, but if the experience of "The Skotch " has been such that his two-ton lorries are working on a consumption of 10 miles to the gallon, then he has my sympathy, but, at the same time, he should make sure of his facts before directing his criticism at a particular chassis, about which one can only conclude he is ignorant. I need scarcely add that I have no connection with Republic Trucks, Ltd., and have merely giveh my opinion as based on the actual results.—Yonrs faithfully, THOMAS CARSON. Sunderland.
Pneumatic Tyres on Heavy Vehicles.
The Editor, TITE COMMERCIAL MOTOR.
[1963] Sir,—We have read with much interest your article "Help for Hauliers" in last -week's issue of The Commercial Motor and note that the writer is not in favour of the pneumatic tyre on heavy vehicles, and that he says experience is against the use of such tyres on vehicles of a greater capacity than 30 cwt,
In this connection, we would desire to say that., whilst this may be correct with regard to pneumatics fitted with the ordinary bladder-tsrpe of tube, it is not correct with regard to tyres fitted with Compression Tubes, with which we have now gained more than ample experience under heavy loads to justify • our claim that, apart from the saving in the cost of new tubes and, of course, the entire abolition of puncture trouble and the expensive delays attendant thereupon, the use of these tubes so increases the life of the covers as to make them in every way a practical proposition for heavier trucks than 11 ton, which your contributor considers the limit.
For example, we have before us a photograph of a truck fitted with 40-in. by 8-in. compression tubes which have run 13,200 miles without a puncture or reinflation, and the treads have worn so little that the N. S. moulding has not been worn away, even in the centre where the bulk of the wear is taken, and we have records from users who tell us the are getting 18,000 miles out of their Giant tyre covers when fitted with Compression Tubes, whereas they had hitherto not been able to get more than 12,000 miles out of a cover. Perhaps the best testimony we can adduce is the fact that large users of transport wagons in America are employing pneumatic tyres—fitted with Compression Tubes—on all their fleet. Thus, the Prairie Pipe Line Co., who have bra:riches in several parts of Oklahoma and Texas,
and have no fewer than 400 motor trucks, are using Compression Tubes on all of them, and report that: "We are obtaining the best of results with them" and, as to exact figures, they state that, on aorta:in trucks mentioned, although their best record on any cord or fabric casing equipped with bladders was from 5,000 to 6,000 miles, since fitting Compression Tubes they are " able to run 20,000 miles on one set of casings."
Facts like . these .speak for themselves and it is not fair to condemn a system if employed with inefficient material.—Yours faithfully,
BRAMCO (1920), LIMITED.
Lubrication of Shackle Pins.
The Editor, THE COMMERCIAL MOTOR.
[1954] Sir,---We notice that Mr. Sydney Guy, in his article in your issue of May 23rd, says that grease when used in shackles solidifies in course of time and becomes more or less a solid mass. Is that what happens to Mr. Guy's stock of unopened barrels or tins of grease, We rather think that the solidification. is dependent upon the introduction of foreign matter, and we believe that that foreign matter will find its way into the oil duct just as easily as it did when the same duct was filled with grease, with the result that, not only will the oil cease to function as a lubricant, but it will prevent the introduction of any fresh oil, and, owing to this, the shackle pins will very soon bind, causing excessive wear.
The smallest obstruction will suffice to prevent the oil running through the duct and reaching the place where it is wanted and, in the Guy type of shackle bolt, there is no possibility of putting any pressure whatever upon the lubricant with a view to removing the step. As a rule, however, the screwed down form of shackle bolt cap does not entirely get aver the difficulty, for the lubricant generally escapes between the threads of the cap.
It would seem, from the way in which the JM greaser bolt has been so extensively adopted during the last two years, that the JM cap gets over the difficulty. The lubricant cannot possibly escape between the threads, and pressure can be brought to bear upon it so that any foreign matter in the duct is ejected and the way is kept quite clear for the lubricant.
The accompanying illustration shows the J111 greaser bolt with a patent spring gland inside the cap which expands as the cap is screwed down, making the escape of grease past the threads impossible and forcing it where it is wanted. —Yours faithfully, THE STREATHAM ENGINEERING CO, , LTD. 1343