FORD VAN POINTERS.
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By R. T. Nicholson (Author of "The Book of the Ford").
LAST WEEK I advocated the use of a. fuse introduced into the battery lighting and ignition circuit, and said that it was as desirable an item of that portion of the equipment of a Ford as of a vehicle of any other make. I will now go into certain details concerning the manufacture of a fuse and its fitting.
572. Contd.—" The Right Place for a Fuse."
I would put the fuse in the circuit near the point where the yellow wire leaves its anchorage at the foot switch. In that position it would come into operation—that is, would melt, or "blow "—if at any time a bad " short " occurred in any batteryfed circuit other than the starter circuit. It should "be a fuse of more than 12 ampere capacity—not much 'inore—that is to say, it should " blow ' when called upon to carry rather more than 12 amperes. The yellow wire is legitimately called upon to carry as
Fuses. much as 12
amperes when the
5. otnici. /gimp. /5, am, generator is r charging at its normal maximum. This means that the capacity of the fuse in amperes must be rather h i,g h e r than the 12 amperes which the generator can deliver when the engine is running at a good " bat.
Fitting the Fuse.
Fuse wire can I-A3 bought at any Fig. 316.—Showing a method of garage or at an strengthening a 5 amp. fuse wire electrical supplies so that It will conduct 15 amperes. shop. It is made
in various thicknesses and grades (that is, of different alloys of tin and lead). The thickness and grade make a difference to the amperage capacity. Within wide limits the length makes no difference at all. Each strand Of a particular kind of fuse wire will carry a given number of amperes. A convenient .wixe for use on the Ford is 5-ampere fuse. A single strand of this will carry 5 amperes; two strands will carry 10; three will carry 15; and we want about 15 amperes' capacity on the Ford-15 amperes being rather higher than the maximum charging rate of the generator. • (If the fuse would only carry the maximum "charging rate—or less—the wire would, of course, be continually fusing.) .
To fit' to the Ford, twist three strands of 5-ampere fuse wire together, having first threaded them through the terminal eye of the yellow wire, which you will remove from its foot-switch anchorage for the purpose. Make an eyelet of the fuse wire at the other end, to fit the terminal to which the yellow wire was previously attached. Slip the fuse eyelet over that terminal: over the fuse (or, rather, under it) put a light washer ; then tighten up the nut gently. Do not use too much pressure, or you will squeeze the fuse flat and it may break. To prevent the weight of the yellow wire coming on the fuse and also to support the fuse itself, wrap the fuse and.' the terminal of the yellow wire with thick sheet rubber (which will also act as an insulator)
(if you can get a bit of thin eheet asbestos to wrap round the fuse,, so much the better and safer); . then tack the rubber to the woodwork in the neigh bourhood, seeing that the tacks do not touch fuse for terminal. A handy man may devise a more satisfactory attachment, but this arrangement will serve.
Its use is delicate ; do not handle it roughly ; do not expect it to last for ever ; vibration, will almost certainly break it in the long run ; so be prepared to replace it ; carry a spare length ; fuse wire is cheap enough ; in attaching, avoid kinks, or you -will get a break at once ;.if you want a spare fuse one day and cannot get 5-ampere wire, take any fuse wire that will enable you to make up from 14 amperes to 15 amperes capacity—say, 7 strands of 2-ampere wire or 5 of '3-ampere wire.
Why Not .a Fuse in the Starter Circuit ?
It is, of course, possible to get a very heavy " short " in the starter circuit. Why not, therefore, put the fuse between the battery and the starter, and so safeguard not only the lighting and battery-ignition circuits, but else the starter circuit?
Because, in the starter circuit, you have to pass a few hundred amperes anyway (for starting). Your fuse there would have to be " some " fuse, would it not? Moreover, it would have to be so heavy that it would not safeguard a " short in the .lighting and battery ignition circuits. Further, the risk of a " short " in the starter circuit is very slight, there being only a few feet of cabling, and the insulation being very heavy ; then, should a " short " occur there, you are pretty certain to be present at. the time to scotch it.
573.—Is Current Passing ?
(We are now on another, though a related, subject.) With all switches off, and with the engine at rest, there should be no current passing. If no current passes there can be no risk of fire. Current will paSs., however, with all switches off, and with the engine at rest, if there is a " short " in any of the battery circuits. In that case your ammeter should, and normally would, indicate "Discharge," and so give you proper warning. The right thing to do in such circumstances is to take off the positive battery _lead from its terminal at once. You have still to find the " short," but you can take your time over that. By detaching the positive lead you have cut out the danger.
Irrespective of the ammeter, or if your ammeter is out of order, you can always tell whether current is passing from the battery when it should not do so by removing the positive lead and flicking its terminal lightly against the. battery pole from which you have removed it. If current is passing, snappy. sparks will be seen (and heard) at each touch. -A still better way is to take the terminal off, and then, while holding a thin wire against the empty battery pole, flick the free end of the wire against the positive terminal of the lead which you have removed. The thin wire will take very little current, 80 that your test will not draw on your battery to any extent. It will show the snappy sparks Just as well as the battery lead itself will do.
The flick test is not generally known—except to " professionals." It is easy and convincing, and for that reason I have recommended it in my "Book of the Ford Electrical Equipment " for various purposes.
A Wise Precaution.
Whenever your van is going to stand by for any length of time, make it a rule to remove the positive lead from the battery, setting its terminal somewhere where it cannot touch the positive. pole from which you have detached it. You will then know that you, have taken the best possible precaution against self-ignition.
Further, whenever you are "dickering about" with any of the electrical equipment on the van, take off the positive lead in the same way.. You will then avoid various oleetrical troubles which otherwise might happen.
When hunting " shorts," keep the positive lead 'off during your investigations. When you think you have found and cured them all (though it is to be hoped there is not more than one), all you have to do is to flick with the thin wire in the way have described, and if no snappy sparking shows at each flick, you will know that the wiring connectedwith the battery is all sound. If, however, the sparking shows; with all switches 'off and the engine at rest, you will know that you have still to go on hunting. • But on no account 'forget to replace the lead before you run the engine. Failure so to do means a big strain on your generator ; further, if you i switch on your lights with things n this condition, they will at once .burn out, because the generator current will pass direct through them, and they are not strong enough to stand it.