FORD VAN POINTERS.
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By R. T. Nicholson (Author of "The Book of the Ford ") .
I " CAN'T GET the hang of this wiring!" is the plaintive cry of the driver; the owner, or the garage hand, when he is "looking for tr.ouble" in the electrical fitments of the 1920 model Ford.
214.—The Electrical Circuits of the 1920 Model.
In the ordinary run—i.e., when everything is going well—the driver, the owner, and the garage hand need not worry over the wiring. But when trouble doeg` arise, "the first duty of man "—Cr master—is to "get the hang" of the various circuits—including the wiring. That is the first necessary step towards pinning down, and sewing up, the fault..
Necessary Knowledge.
But I do not promise you that, even with a clear knowledge of the circuits and the wiring, you will, in absolutely every case, be able to set things right when .trouble arises ; but I do say that, -without such knowledge, it is utterly unlikely that you will ever be able to set things right. On the other hand, it is true that, in nearly every case of trouble, knowledge of the circuits and wiling will put you on the right track; and then, if you have just a smattering of the first principles of electricity (as set out later on), and good commonsense, you ought to be able toput things right and get going again.
1-` ComPlications."
Yes, I quite agree that thecircuits and wiring of the electrical outfit of the new Ford. look terribly conaplicated. (The same is true of every motor that uses electricity for a large number of purposes; though, in the case of the Ford, the wiring looks more than usually complicated, because the Ford magneto ignition system involves a great deal more visible wiring than the standard magneto system— the low-tension wiring of which does not shoW at all.) But, as a matter of fact, the Ford circuits arequite simple when. traced through. It is only because there are so many circuits, and because it is so difficult to trace them through, that things look complicated'.. That is why the wail, "I can''.; get the hang of the wiring!" rings out on the troubled air. Which distresses .me; and it distresses me to be distressed. Therefore, have I put on my thinking cap and said unto myself : "What can I de to relieve human suffering(and, incidentally, to make a bit for myself)!" And this contribution is the outcome of much hard thinking and many pipes. I have come to the conclusion that the only way to give anybody a clear idea of the various circuits is to trace them out singly and separately from start to finish—to take each circuit alone, and follow it right through, cutting, out nisi_ the others for the time being; and that is just what I am going to do.
First Principles.
BefOre I start 02t tracing a single circuit, however, let me briefly set dawn threeifirst, principles, which must be clearly understood at the outset, and which must be borne in mind right thl-ough our investigations because they are the vary rock-bottom of the subject. I have gone over the same ground before in these Pointers but it will do no harm to tell the truth twice.
I.—An Electrical Circuit, to Exist at All, Must Be Complete from Start to Finish.
This means that if, for instance, you connect up the two poles of a battery by a length of wire (which do not do I), you get a complete circuit. The wire is then electrified. But, if you eut the wire at any point, do not imagine that the electricity gets up to the gap and is waiting on each side of it, "ready for use." When the circuit is broken, the wire (or other conductor, as the case may be) isnot electrified at all. The only exception to this principle-arises when a very .slight gap exists in a circuit: then, if the electrical pressure is high -enQugh, the Current will jump the gap (as a spark), . and so complete the circuit.
IL—An Electrical Circuit that Starts from a Particular Source Must Always Finish at that Same Source, and Will Do So if the Circuit is Complete.
That is to say that magneto current will always complete itself at the magneto, battery current at the battery, andgenerator current at the generator, if the circuit is complete in each case. Yoli cannot get battery current tc finish with the magneto or with the generator ; or generator current to finish with the battery or with the magneto ; or magneto current to 050
finish with the generator or with the battery. True, you can run the battery, current through the magneto or through the generator (though you simply must not do these things I) ; but you cannot get' it to finish with either magneto or generator. The, circuit is always from " home " to " home." Get this quite clear. . But in the name of eommonsense, do not experiment by connecting up the battery with the magneto, or with the generator, to see if what I say is true. Take it as true. You will only do big damage if yoti, for instance, connect up the battery with themagneto.
I11.—A Circuit Need Not Consist of Wire. Any Conductor Will Carry the Current.
As a matter of practical.convenience (generally with the object of getting thp• electricity up to and through a particular point—where it does its job), part of a circuit, at all eients, is usually of Vire (nearly always of insulated wire, tlie insulation being there to prevent a "short circuit "—that is, a short cut back " home" before the job. is done). But the latter part of a circuit is often-Lindeed, usually—not of wire. In that ease, the current is said to be" earthed."
The word " earthed " is mi'sleading, because the earth on which we live, move and have our beingdoes not enter into the circuit at all—in the cage• of a motor electrical outfit. Earthing means getting "home " through' some conductor other than wire—generally
through the engine or frame. (In all cases, wire could be used for the return , journey, but it is not needed. True, use of wire throughout might, perhaps, make things simpler for you to understand, as you would be able to trace the circuits complete ; though, on the 'other hand, there would be such a lot of " wire entanglements" about that you might get worse confused than ever. Anyway, it is cheaper for the manufacturer not to use wire ; so he does not use it where it is not necessary.)
it is the "earth" part of a. circuit that bothers the beginner most. There is nothing to show that it is there, and you cannot see the electricity running along the " earth " part of the circuit. And when they give you a nice picture showing the details of a circuit the lazy artist generally gets tired just as he. gets to the earth connection, drops his pencil, goes to sleep and leaves you-wondering what happens after that—how "on earth" the, current gets "home." (But my own particular artist is not like that ; he is very paa-timilar indeed. You will notice that in most of his illustrations in this contribution, every " earthing" is shown by a pretty sign, something like a striped .s.vhiptop, and every "earthed" current by a dotted line.)
Now to Details.
Enough of theory, however: let us get down to practical details. • Fig. 131 gives a general view of the new model Ford electrical fitments, in their surroundings. The electrical details areboldly drawn: other details are shadowy.
Fig. 131 is "true to life," except perhaps in one minor detail. Most Fords have the tut-out on the dash—not on the generator, as-illiistrated." However,
that need not worry you, because the cut-out may be in either position, and it makes the illustration simpler to show it on the generator.
But I could not pick out the individual circuits as I want to do, if I dealt with the details as they shOw in Fig. 131. Wires are so often tucked away out of sight—passing under covers (or " looms "), often with a lot of -other wires—that it is impoSsible to follow the individual circuits clearly in that illustration. In the next illustration, Fig. 132, the details are given in. " diagrammatic" form—by which I mean, iii a sketch that shows every detail "as plain as a pikestaff "—though this details are not necessarily in exactly the positions which they occupy "in real' life," nor necessarily true to size. In Fig. 132 all covers to the wires are cut away, and there are no
"tunnels," so that every circuit is in plain sight—. including "earthed" portions, which are indicated by dotted lines. (You must not, however, suppose that any dotted line shows exactly the -course which an earthed -current takes, though in each case it is "something like that." Exactness here does not matter, and is impossible anyway.) You "do not think Fig. 132is very clear?" No— not yet: but wait a bit, and you shall see clearly enough. I'll make you!
Fig. 132 does not look very clear because there are such a. lot of details in it. What I am going to do in subsequent contributions is to pick the puzzle all to pieces, and show you a bit at a time, so that at the finish you may see where every bit belongs, and how it fits into the whole scheme.