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• FORD VAN POINTERS

4th October 1921, Page 43
4th October 1921
Page 43
Page 44
Page 43, 4th October 1921 — • FORD VAN POINTERS
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Which of the following most accurately describes the problem?

By R. T. Nicholson (Author of "The Book of the Ford").

ORE correspondence. It is always welcome, thosigh again I am going to refer to the

. sordid subject of stamps. Fordsmen all, I am ready to tell you all I know, but, if you want a reply by post, do, please. remember that a stamped, addressed envelope: is essential. I hold my brains cheap, and my time is at your disposal, but I do hate patronizing the Post Office.

394.--A Kicker as a Starter.

"J.W., Warrington, writes. have a Ford one

Tim Car only about 12 weeks old. I have had riothing but trouble since.' received it and the trouble as near as I cast tell you is this. I might go and give her one swing and away ehe, will go now the next time I go to her I might swing an hour and nothing doing not only when she is cold but the same when she is hot and when this happens so how she is swing you can not feel any thing at the plugs but if you will use a, 4 Volt accumulator she will start everyAinie. Now the plugs & Tremblers & corn are in good order. The light when she is running is just, a dull red, but when she etarts she runs all right and pulls the same. Now I will tell you what I have done. I have taken all the magnets out andsreplaced with new ones and looked at all the stator coils and as far as I can see all is in order but she is no better in no respect. Now lam. a, constant reader of the Commercial Motor I have before me now as I have been looking up Auguet 17, 1920, Ford Van Pointers No. 246 Insulation of Sator Coils wich read just how she is now can you help me in any way an answer will oblige by post."

• I have printed J.W.'s letter word for word because it shows that J.W. thinks, and I believe in giving the thinkers a, show.

I told ,J.W. by poet) that the trouble was undoubtedly magneto output (inasmuch as his truck starts well enough on a 4-volt battery—which, by the way, is none too well-qualified for starting purposes, the voltage-4--being pretty low—though, the fact that it did start on 4 volts shows that everything, is in excellent trim except the magneto).

I advised J.W. that two eimple courses were open to him. (1) To take out the magneto contact assembly, and clean, it thoroughly, removing also any dirt (in the shape of flu or otherwise) he might find lodged on the plate from which the contact assembly had been, removed. (2) To flush out his crankcase . thoroughly with paraffin. (Both these jobs are described in detail in " The Book of the Ford Van.") The idea in either ease is to clear away or out any foreign matter responsible for a short circuiteof the magneto current.

The dull red glow of the lamps shows that much of the magneto output is being short-circuited, or interrupted.

I also suggested another still simpler course to J,W.—His truck is under guarantee. It ia up to the Ford dealer who supplied that truck to see that c55

things are put right. J.W. has already done enough investigation. A 12-weeks old truck ought to have no vices; though, as a matter of fact, such a trouble as is described is more likely to arise in the early life of a Ford than when good mileage has been done, because, in assembling a new Ford, bits of foreign matter are often left in the " innards," and these are quite tapable of upsetting the magneto output.

395.—Real Jam.

" CM.," Peckham, writes picturesquely of the case of a jamming starting motor :— " I am a driver of 25 years' experience but have only actually had charge of a Ford duringthe last twelve months.. Some months ago it was fitted with a new brake band and a day or so after when using the starter, it _seemed to mesh too deep and jammed everything up.

I could not move the engine by the starting handle or by moving the car in gear. The starter was taken down examined found all correct and present and replaced and had given no more trouble. In this case we. learned nothing. Last Saturday evening I was out with the car and' everything seemed all correct. I used theestarter at London Bridge at 1.30 run to Deptford discharged passengers about 1.40. Of course I stopped the engine, while taking out wraps, parcels etc. ,Then starter used,—ping—silence---get out and try starting handle—all jammed again, quarter mile to garage, and car wanted at 7.20. So pushed car the nearest street lamp, undid holding s6‘evss in front, removed bendix drive cover and turned starter spindle reverse way to release pinion

• replaced cover and holding do-wn screws in front and started ear by handle. I give the above, times to 'show the inconvenience and you may guess, how happy I was. The only thing I was thankful for is it was not raining. I did not dare use the starter on Sunday in ease it started its tricks again. I tried it today and Of course as. I had plenty of time it was quite alright.

"I have made a few enquiries today and have heard (second hand of course) of at least three others who have had the same experience. So possibly it would be a defect the cure of which might be made public, or its prevention."

" C.W." not only thinks, but acts: mare—he knows how to tell exactly what happened, which is. a gift!

One thing stands out quite clearly in the facts as related. The starter is somehow out of truth with the engine. It is somehow so set that it meshes too low at times—perhaps all the time, though trouble arises only when the meshing happens to besexces-sively low. Now what can this be due to?

(1) In putting on the transmission cover, after its removal for replacement of the brake lining, it was set too low, or was set too low on the starter side.

056 This might happen .j.f the bolts were screwed down very tightly or unevenly. Unlikely, however. (2) The starter shaft hasp got .bent. This would result in the meshing being at times _too high, at others too low ; and the too low meshing would cause the "jam." (3) The starter shaft bearing is too tight or badly assembled.

The second of the above-named causes is the most likely source of the trouble. The clearance at one point—i.e., the clearance between pinion and flywheel teeth—is probably so small that the slightest thing —say, a piece of dirt—" queers the pitch" and causes the jamming. It ought not to be a difficult matter to check the straightness of the shaft. If the Bendix cover is removed and the foot switch is depressed, the movements of the pinion can be watched. If they seem te be up and down, they are undoubtedly wrong. The shaft, and the pinion on it, should run _absolutely true, without rise and' dip.

In -testing thus, have the ignition switch set at " off" when the foot switch is depressed. The effect then -will be that the starter runs the.ilywheel continuously instead of the flywheel trying to turn the starter. Do not, however, make the test a long one, or you will risk running the battery down.

• I congratulate "C.W." on the way in which he overcame his trouble temporarily by turning the Bendix shaft backwards. That was the only thing tosdo for quick action, with a job nearly due. Yet not everybody would have thought of this simple way out.

396.—Why Does, a Bulb Light Up?

(Really, the bulb -does not light up at all: it is the • filament in the bulb that glows. But no matter!)

When current passes through the filament, it does so (as the Scotsman jokes). with difficulty. The difficulty comes from the fact that the filament is so -thin. If you had a thick filament it would not glow, except a dull red, perhaps. The filament is a good conductor of electricity, so far as its material is concerned; but the material is spun out so fine that it really offers quite considerable resistance to the current. That resistance means that great heat results. The longer a thin filament, the greater the resistance and the brighter the light. So a " dim " filament consists of a single loop, which may be relatively thick, while a " bright " filament consists of a long " twiddle " of wire.

397.—The Resistance of Conductors.

Which brings me to another point. We say that certain materials conduct electricity, and that other materials do not. For instance, we say that porcelain does not conduct electricity, and, therefore, use that material for sparking plug insulators. We say, on the other hand, that copper does conduct electricity, and therefore use that material for our wires. The truth is that all materials whatsoever-resist the passage of electricity. All conductors are really resisters. Some substances however, offer greater resistance than others, and we call such substances bad conductors, or non-conductors. None of them are non-conductors; all substances will, given enough pressure, "pass" electricity. On the other hand, the best conductors, offer some resistance to electricity.

Further, the amount of resistance offered to the passage of electricity by any conductor depends upon the size of that conductor. We haye just seen that in the case of the electric light filament. Increase the size of the conductor, and you make it easier for the electricity to" pass." By " size," you will, of course, understand thickness—not length. The greater the length, the greater the resistance. That is why, in the case of the "bright" filament, we decrease the thickness of the material and increase its length.

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