OPINIONS FROM OTHERS.
Page 50
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Plugs for Ford Ignition.
The Editor, Tins COMMERCIAL MOTOR.
[1749] Sir,—With reference to the instructive and interesting article on sparking plugs for Ford ears in your issue dated September 21st, 1920, we are glad to see that some effort is, aclast, being made to give publicity toward8 the need for fair and careful treat meat of sparking plugs. We might say that well over 90 per cent, of the plugs, returned to us for examination in cases of apparent breakdown, _are faulty through ill-treatment due to lack of knowledge on the part of the owner of the correct method of using and treating plugs. We have endeavoured, by means of a small booklet entitled "Plug Tips for Plug Users," lo help things along a little in this direction, and we would say that we should be very glad to furnish your readers with copies of this booklet, free of charge, in the hope that it may be helpful to them. Further, we would point out that we are not in agreement with your contributor when he states that mica plugs may be cleaned without harm by the use i of a wire brush. A prolific cause of trouble n cheap mica plugs is the bad surface of the mica in the plug bowl, where it cannot be seen, causing the cracks and 'crevices due to bad finish to fill up with soot and oil, which is very difficult to dislodge. Consequently, in a good mica plug, as will be seen, a great deal of care is taken to provide a glassy finish on the surface of the mica. Mechanical scraping by hard, sharp instruments soon damages this surface and causes the mica plug to oil up again in. a very short period. One objection we have to the use of a mica plug in the Ford engine is that the engine runs with a comparatively low, explosion temperature and, in many cases, runs decidedly on the oily side. Under these conditions, the plugs are bound to have their insulations covered with a, layer of soot and oil in. a certain period. To guard against this, a porcelain skirt is fitted into the Ford plug so as to render the conducting path, which is caused by the soot and oil, as long as :possible. We know of no mica plug at present which satisfactorily provides so long a leakage path. Nevertheless, in a hot running and dry engine, we agree with him that there is nothing to approach the mica plug. With regard to the adjusting of the gap between the electrodes, we should like to point out that, for plugs with " wire " points, we recommend these to be adjusted in preference to the central electrode. Constant adjustment of the central electrode is apt seriously to weaken it at the junction 'between the nickel electrode and the steel stem, whereas the wire point will stand a good deal of bending about.
In conclusion, we think your contributor has barely done justice to the question of single v. three-point plugs. Owing to the alteration of current across the plug points caused by the rotation of a magneto armature, single-point plugs require different gap setting in alternate cylinders owing to the great difference of potential required to jump a gap between a plane and a point, and a point and a plane.
Also, in a well-set three-point plug the spark will change its path between the various points from time to time, and we should be pleased to demonstrate this to your contributor should he care to call and see us at our London showrooms at any time whatever.
In a hot engine this is a distinct advantage, as severe local heating is caused by the spark itself and, in some cases, this is sufficient to cause pre-ignition. We agree that there are few Fords fitted with ordinary types of magnetos, and also that it is not by any means a hot running engine, but we feel that your contributor's remarks might be misleading to users of cars other than Fords who may read his excellent article. May we conclude this letter by congratulating your contributor on the extreme clearness and completeness of his article 2—Yours faithfully, .
THE APOLLO PLUG MANUFACTURING CO., LTD. London, W. 1.
Bearings on Spring-leaf Ends.
The Editor, THE COMMERCIAL MOTOR, [1750] Sir,—In your issue of September 21st you publish a description of what is termed " Roller Bearing Springs." From the description given and i the illustrations, it is not possible, n any way, to criticise the construction Of these springs. We understand that they are being introduced at the forthcoming Commercial Vehicle Show at Olympia, and, doubtless, it will then 'be possible to see the exact method of construction.
We note that the claims made for these springs are rather extravagant, and we very much doubt whether they'. would give any better results, than springs carefully designed to meet the necessary conditions.
Undoubtedly, there is a lot still to be learnt with regard to the springing of road vehicles, and we think that considerably more is likely to be done by alteration of spring design based on experience spread over a, long period.
This present company, as factory representatives of the Mather Spring Co., of Toledo, arc particularly interested in matters Pertaining to springing of road vehicles, and we hope that, in the near future, we shall be able to publish details of results of extremely important researches which have been made by the Mather ' Co. during the past few years., and which will, we think, be extremely interesting to both manufacturers and users,. of ears, etc.—Yours
faithfully, AUTOMOTIVE PRODUCTS CO. London, W.1.
Coach Owners' Co-operation.
The Editor, THE COMMERCIAL MOTOR [175ij Sir,—As a motor coach proprietor with an extensive 'connection in the North, I have been extremely interested in all that has appeared in The Commercial Motor concerning the industry, and, particularly, what has been said concerning the formation of a motor coach section of the Commercial Motor Users Association. I am not acquainted with the latter body or its aims and ideals (beyond what is conveyed in its title, which, of course, gives me a fair indication), so I am asking you to put me into touch with its secretary.
I am decidedly of opinion that such a section is rapidly becoming a necessity. There is a number of matters that we coach owners must "get together" upon between now and the commencement of the next season. The constant changes in local by-laws and regulations and the development of the ideas of the police call for equal activity on our part so that we can meet these matters, not after they have come into force, but ca-n lend a hand in the making and development of them.
There is alwa's the need for concerted action in any case of injustice," actual or threatened. There is the need for 'co-operation in the drafting of fare bills—it is a common experience for one of us to find his fare bill taken and copied exactly by the newcomers among his competitors, whereas a conference beforehand would help us to frame schedules of fares that would be acceptable to coach owners and public, and we should not show so much " raggedness " in our services at the start and finish of the season, at both of which periods there is much avoidable
competii ion.—Yours faithfully, COACH OWNER. , 'Barnsley.