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12th July 1935, Page 42
12th July 1935
Page 42
Page 43
Page 42, 12th July 1935 — OPINIONS and QUERIES
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Which of the following most accurately describes the problem?


[4587] In my opinion, all this talk about cylinder corrosion is absurd. The real cause of cylinder wear is this. The piston, on its suction stroke, draws in petrol in the form of a spray, vaporization taking place inside the cylinder. On its entry, this spray comes in violent contact with the side of the cylinder opposite the valves (marked A in the accompanying diagram). As a result, the oil is washed away, or nearly so. On compression, the thrust exerted by the piston is taken by this dry side of the cylinder wall, and, owing to the absence of lubricant, high friction takes place, causing wear.

When removing pistons, many people expect to find the wear at B, and are at a loss to know why it should occur at A. In theory, wear should take place at B, because this side of the cylinder wall takes the thrust on • the power stroke, but, in practice, the wear is more marked atA. I suggest that the =only way to reduce cylinder wear is to fit overhead valves and slightly to dope the fuel. FLEET ENGINEER. Enfield.

[This explanation sounds plausible, but is hardly in agreement with the corrosion theory which, few will dispute, has been conclusively proved. Furthermore, our correspondent's sweeping statement as to " the only way to reduce wear" flatly contradicts the claims—for justification of which convincing technical evidence can be produced—made for oils which, by the addition of deoxidizing agents, the removal of undesirable constituents, or the admixture of colloidal graphite, have been prepared expressly to prevent corrosion—En.I


[4588] Our attention has been called to letter No. 4563 in your issue of June 7 regarding the 'effect of worn tyres and the reply given to this 'correspondent.

. B28

His description of the trouble, viz., that "side-slipping occurs without any application of the brakes," suggests that the condition of the tyres is not responsible, and, further, that there, must be something there causing the skidding which the tyres are not able to resist. It is, of course, very difficult indeed to diagnose trouble accurately from letters.

We notice that your correspondent, who uses the nom de plume "Tyres," is located in Birmingham,. and if you would like to give us his name and address we will get in touch with him to see whether any practical sug gestion is possible. W. B. SroxEs, For DUNLOP RUBBER CO., LTD. Fort Dunlop, Erdington, Birmingham.


[4589] According to statistics recently published there were over 360,000 motoring offences during 12 months, which averages something like one in every six motor drivers in the country. One wonders how an analysis of the figures would work out, .just how many of the offences were caused by idiotic regulations, such as lighting, parking, dirty number plates, to mention only a few.

Clearly, then, here is a case for a round-table, conference of all patties, including the A.A. and #,A:C., on the private-car side. From such a meeting surely a list of regulations, embracing every, point, could be hammered out ; regulations, of course, which must be reasonable to employee as well as employer, this being presented to the Government in the form of a demand, not as a plea. Should it be rejected, as it undoubtedly will be, there is yet time before the general election for the industry, whilst, perhaps, not sinking the ship of State, to create some uncomfortably high seas around it.

Whilst one has no desire to bring political affairs into the confines of your excellent technical journal, it must be obvious to your readers that the present Government, swayed, no doubt, by vested interests, is doing its utmost to prevent the development of the Motor industry. One example will suffice. Part of the emergency regulations of 1931 was the increase of 4d. per gallon tax on petrol. Most of the emergency " cuts " have now been rescinded, with the exception of the petrol tax, which has been followed by the now well-known tax on oil fuel, just to bring the latter tax into line.

One wonders for how long and how far this sort of thing will go on. Can the 'internal squabbles not be held over, even temporarily, while both industri6iire sent a united front? For it Gan truthfully be said arthe . _ moment that there is no road-rail fight, as the road side has less kick than a fully retarded engine.

Glasgow. A. R. WILSON.

[There is no objection to bringing political matters into • the columns of this journal, provided that they have a direct or indirect bearing on the prospects of road transport. We have stated on many occasions that the industry must rely more fully upon political pressure if it is to obtain freedom from at least some of the shackles by which it is now impeded.—Eo.1 NEW VIEWS ON THE LONG PERIOD OF REST.

[4590] You inform Mr. M. E. Small, of Ihrtinster, in your correspondence columns (letter 4584), that it is not permissible fn a driver to take his long rest period in the cab, as the Act states explicitly that this rest must be taken away from the vehicle.

The unforgivabk error is that, as you know well enough, no Act of Parliament states anything "explicitly." The Road and Rail Traffic Act, 1933, does not differ from other statutes, although it does make it illegal for a driver tolake his long rest in the cab, either if the vehicle be at a place where no reasonable facilities , exist for him to rest away from the vehicle, or if his terms of employment or instructions as an employee force him so to do.

Should the driver, however, have free choice and not be bound by his employer to rest in the cab or stay in the vehicle, and should the vehicle be at a place where reasonable facilities for rest away from the vehicle exist, then he could have his 10 consecutive hours' rest under the bonnet or on the back axle without infringing the law.

Concrete examples are always best. I was asked my opinion (by an otherwise perfectly sane man) in a case where a lorry driver drove a lorry through the front room of the actual driver's rest house, where he usually put up, just at the expiration of his 14-hours' spreadover period. The proprietress, used to the fun of haulage drivers, never came down, and the driver, not too anxious to advise her of his arrival, took his rest of 10 consecutive hours in the cab. h was obvious that that

was perfectly legal, as his employer had neither instructed him to go through this house nor to remain on or near the vehicle, and he was quite free from any employment terms and instructions, whilst the vehicle was at a place where reasonable facilities existed for rest.

London, S.E.4. F. A. Full, Director, M.T. Co. (McrroR COACHES), LTD.

[We accept Mr. Flin's reference to our " unforgivable error " in the spirit in which it was obviously intended. We fully agree that "explicit" is a glaringly wrong term to apply to almost any Act of Parliament. They are usually full of loopholes and inconsistencies which it takes years to stop up or rectify.—En.] A WELDING EXPERT'S VIEWS ON CYLINDER. HEAD MATERIAL.

[4591] Every week we receive for repair scores of cylinder heads and cylinders belonging to petrol and oil engines, and we find that there is a marked difference between the condition of the metal in the cylinder heads of these two types of engine. The metal in the petrolengine heads is almost unaffected by the heat of the engine, brit there is a pronounced change in the nature of that of the oil engines after the heads have been in se'rvice for some time.

Whilst we are uniformly successful in the repair of both types of part, the latter gives us more trouble owing to this deterioration in the metal, due to the great heat to which it is subjected. Frequently we have to cut out portions of defective metal and to replace them by welding in new pieces.

If, as appears to be probable, the oil unit is to be the 'engine of the future for self-propelled vehicles, it is important that owners should be assured of a reasonable length of life in the engine parts.

The problem of baring load appears to have been solved, and special attention should now be paid to the composition of the metal in the heads, so that a suitable alloy can be devised Which will not deteriorate rapidly at high working temperatures.

C. W. BRETT, Managing Director, London, W.C.1. B.ARIMAR, LTD.

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