FORD VAN POINTERS.
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By R. T. Nicholson (Author of "The Book of the Ford").
THERE is no doubt that the presence of a battery on any motor vehicle means some risk of
fire. . in the battery you have a pent-up store of electrochemical energy, and that energy is capable, in certain conditions, of expressing itself as heat— considerable heat—and when it does SQ the risk of fire is very real.
471.—Fire
The " certain conditions " referred to are, in a word, " shorts "—short circuits whereby the current gets out of storage, and finds a wrong way back through the "earth" connection to the negative terminal of the battery.
Have you ever thought what would happen if the insulation of, say, the yellow wire got chafed through, and the bare copper wire • inside came into contact with some conductor l First, there would be a rush of current-from the wire, to and through the conductor. Presereably, the conductor would be of metal, so that it could hardly catch fire itself through the heat produced by the " short." The danger lies in the chance that the conductor might be in contact with some inflammable material—say, wood—and the heat produced in the metal by the rush of current might then quite well set the wood
There' is a second, and graver, danger. When the " short " is a big one—when, that is, the copper
wire is in good contact with a conductor which is ready to take all the current the wire can deliver —there is a big rush of electricity along the wire which grows very hot—red hot—anti may set fire to its own insulation or to any inflammable material against which the wire at any point lies—any point, I mean, between the battery and the "short."
— Actual Cases of Fire Caused by " Shorting."
Now this risk is by no means imaginary. I have heard of quite a number of instances where fires actually occurred. A doctor recently wrote to me to tell me that his Ford and his garage had both
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been destroyed by fire in circumstances which led him to. believe that a " short" was responsible. I can quite credit it, for a Ford dealer lately told me that he had known "shorts" occur when he was actually driving—" shorts" which might have had serious results if they had not been noticed in time. I have known other cases. In one instance the owner of a Ford kept the car at a garage some little distance away from his house. One evening, shortly after he had run it in for the night and had gone home, he was recalled by the garage proprietor with the alarming message that the electrical wires were too hot to touch. he hurried round, of course, and on arrival found that things were pretty, far gone—that fire would undoubtedly have broken out before long. He stopped the riot by disconnecting the battery positive terminal, when, of course, the flow of .current immediately ceased and the danger was over. But most of his wiring had to be replaced. I do not want to give the impression that Fords are particularly liable to this trouble, or that it is Fords only that suffer from it. All motors on which batteries are used are liable to it. I greatly wonder that the insurance companies do not take more serious views of their risks. There is hardly a motor on the road that is properly safeguarded against liability to " self-ignition ' from shorts. And the method of safeguarding (on which the insurance companies might insist) is so simple—a fuse.
472.—What Is a Fuse ?
A fuse is a bit of soft wire (generally—like solder. --made of a mixture of lead and tin) inserted in a circuit. When, owing to a "short," excessive current passes round a circuit, it heats everything up—the fuse included. But the fuse, being thin, and being made of metal that readily. melts, " blows "—actually does melt, and so at once interrupts the circuit, so that no harm _is done. The heat which would cause a fire is thus made the very means of preventing one.
There are always fuses in electric lighting circuits in houses and offices, the idea being that if more current flows along the wires than they can stand and so heats them to the danger point, the fuse will "blow "—melt out—and end the risk of fire. The fuse is the weakest link in the electrical chain, and so goes first. If this provision is necessary in a public lighting system, why is it not equally necessary on a motor'? Frankly, I do not know ; but I do know that too few motors are fitted with fuses.
Why are Fuses Rarely Fitted ?
I think that motor manufacturers are shy of fitting fuses mainly because they have to be treated gently and with some intelligence.
First, they have to be nicely fitted,' and, when replaced at any time, the fitting has again to 'be skilfully done. The wire of which fuses are made has to be so soft and so thin that it is easily broken by rough handling, or even by the pressure that holds it in position ; and then good-bye to current till the cause is found and a new fuse is inserted.
Secondly, not every'driver knows enough to check up his fuse ,as his first step in investigation when the electricity fails. The experienced electrician would do so, but the "common or garden" driver might look everywhere else for the cause of hia trouble and so waste good time
Thirdly, it is a bad, but common, practice with the ignorant to replace a spent fuse with "any
old" wire that happens to he handy—a hair-pin, for instance, if there is a lady "on board." Such substitutes are, of course, not fuses at all; their one merit is that they will not blow when things heat up, so that the electricity does not .fail. But as safeguards against fire, they are useless. The practice is little short of criminal. I admit, however, that I should be guilty of it Myself if my fuse gave out. But I should take the very first opportunity of replacing the wire with a proper fuse.
A Fuse for the Ford.
It is not generally known that there was at one time a fuse on the starter-model Ford. Its use was given up, I understand, because it was " officially" considered to be unnecessary. I submit, however, that it cannot be regarded as unnecessary on any battery-fed motor vehicle.
Why only on a battery-fed niptor vehicle? Why not on the old-style Ford, with its low-tension magneto ignition and lighting? Why not on any car fitted with high-tension magneto ignition? Because, though "shorts can occur with low or high-tension magneto systems, they can only occur wlthn the en glue is running ; and that practically amounts to saying that they can only occur when somebody is in attendance. Moreover, the, risk of a " short" with either. class of -magneto is practically whereas, with a battery installed, the risk becomes real, because of the storage.
I will complete my survey of fuse matters next week.