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Reply to Arguments on Springs

10th March 1950, Page 53
10th March 1950
Page 53
Page 53, 10th March 1950 — Reply to Arguments on Springs
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Which of the following most accurately describes the problem?

pURTHER to the recent correspondence regarding

the lubrication of laminated springs which has appeared in your journal, I would very much appreciate it if I could be spared the space to reply briefly to certain of the points raised.

First, concerning W. L. Woodward's.letter, published in your issue dated January 27, this being in reply to mine published on December 30; I am, naturally, very interested in his opinions, although it appears that we will never agree on this, vexed question of lubrication. One instance which he quoted, that of the "dithering dentures," caused by the lubrication of the springs, of a certain 1938 Morris 8 saloon, rather surprised me as I would have thought that the opposite would have been the case, i.e., the " dithering" would have been the result of high-frequency vibrations transmitted to the car body through the " hard" (un' lubricated) springs, and not through the " softer " (lubricated) springs.

Secondly, I cannot let go unchallenged H. R. Houlding's opinion (published January 20) that the sole raison d'être for using laminated springs is the advantage to be gained from the internal friction within the springs, with the result that greasing nullifies this advantage. There are other advantages, e.g., laminated springs are the only ones which form a

complete suspension unit in themv

selves, this being due to the fact that they can serve, as they usually do, as structural members tying' the axles to the vehicle frame and, at the same tithe, eliminating the need for expensive and often complicated radius rods and torque arms or tubes.

Regarding the analogy to motorcycles, it is assumed that H. R. Houlding is not confusing the steering damper with the suspension damper, the function of the former being referred to in J. F. Moon's letter published on February 3. The function of the latter is, of course, to control the coil suspension spring and, by adjustment When required, vary the suspension characteristics for different speeds.

• I would also like to refer to A. J. Hirst's letter published in the same issue as H. R..Houlding's and express my agreement with his very good description of the true function of a shock absorber.

Leeds, 4. J. A. B1RDSELL, B.Sc., A.M.I.Mech.E.

(For Jonas Woodhead and Sons Ltd.) SULPHUR CONTENT OF DIESEL FUEL_ AND USE OF ADDITIVES AFTER reading the letters of R. J. Ginn in your issue dated January 27, and of N. F. Bilton in that of February 17, I am of .the opinion that the former is going too far in dismissing all the work done in the United States as "laboratory work." I would rather agree with the views expressed in the letter by N. F. 13ilton

As a matter of fact an enormous amount of practical work has been done on the road and in the field. Photographs taken of pistons of oil-engined tractors and other machinery in the course of these tests show clearly the connection of the degree of residue accumulation with the content of sulphur in the fuel. I would like to refer to one report in particular—that of L. D. Thomson. S J. Backey and E. L. Conn, in the S.A.E, Journal of July, 1948, which states that when using a fuel with a sulphur content of 0.59 per cent., 20 per cent. of the cylinder-liner surface was coated with varniSh, whereas no varnish was observed when the fuel contained only 0.09 per cent of sulphur.

The same authors report another very interesting test: two engines of the same cubic capacity were used for this, the only difference being that one had three cylinders, the other five. When the sulphur content of the fuel was increased from 0.09 per cent. to 0.59 per cent. the cylinder wear of the three-cylindered engine was 182 per cent. greater than in the case of the five-cylindcred unit. This was due to the fact that a greater amount of the sulphur-laden fuel passed through each cylinder in the case of the three-cylindered engine.

It is true that a great many operators in this country are not unduly worried about the sulphur problem and are still satisfied with the performance of their equipment. This may be partly due to the fact that, on account of the zoning system, some districts are more fortunate than others in the quality of the fuel available.

On the other hand, I have found that there is a general tendency for the sulphur content to rise, and this will be more .pronounced still when the three large refineries now building in this country become active and Middle East crude oil is the basis of manufacture.

It has also been observed that the periods between overhauls are progressively decreasing. Every road user will agree that smoking lorries are becoming a more frequent nuisance and that many have difficulties on gradients All this indicates that combustion incomplete and that the engines are incapable of giving the performance expected of them.

I have found that oil additives do not provide the complete answer to the fuel problem, and I am more in favour of the idea of improving operation by fuel additives. This has been suggested by several experts.

I had the opportunity of observing results obtained by the use of one additive in particular which claims to tackle the sulphur problem at the root by neutralizing mineral sulphur and aggressive sulphur compounds. The additive contained a special agent for this purpose. Tests were made on several engines which were prone to form coke " trumpets " on injection nozzles and deposits in the combustion chamber. Another test was carried out on two-stroke engines, where intake ports became choked after 500 hours' running. In both cases it was possible to run several thousand hours without deposits being formed.

London, N.12. E. W. STE1NITZ, EInst.Pet., A.I.Mech.E (For Industrial Fluids. Ltd.)


Locations: Leeds, London

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