FORD VAN POINTERS.
Page 32
If you've noticed an error in this article please click here to report it so we can fix it.
By R. T. Nicholson (Author of "The Book of the Ford").
WHY do filaments burn out? For two reasons, of which the first does not amount to much in this day. The first reason is that there, is a certain amount of oxygen left in the bulb, inside the glass,. The makers do everything they can to keep out every particle of oxygen, but some leaks in. Whatever gets hot in oxygen, burns up—even you. Your muscles are burning up—literally—all the time. They used to try pumping the air (containing the oxygen) out of the 'bulbs. Now they try filling the
bustrs with nitrogen, which does not support cora i bustion, and which s, therefore, calculated to pre vent the filaments burning through.
435.—The Reasons Why Filaments Burn Out. —
The second reason is in this day more important. The resistance that the filaments offer to the electricity gives rise to a strain on those filaments. Particles of the material get driven off: you can see them as black deposit on the glass. Sooner or later the filament gets so thin at one point that it breaks there. Then there is no longer a circuit through it, and a break in a circuit at any point cuts the whole circuit out.
There is a third reason, though, like the first, it does not amount to much in this day. Road vibration will break a weak filament.
If your bulbs are new ones, and glow, when first lighted, with an intense white light, see if the voltage figure (usually marked somewhere on the bulbs) is high enough. If they are tried bulbs in use, and they suddenly glow very brilliantly, suspect that too much current is getting to them. You do not see how that can be when you have a 6 volt battery "on board"? But are you so sure that your lighting current is coming fromthe battery. Remember that if your battery circuit is interrupted, it is possible for the generator to deliver current direct to the bulbs, and they then burn very brightly for a./very short time_, and it is then all over with them. I have dealt with this point before, but I mention the matter again here 'because it is suggested . by what I said recently as to running with a loose " earth " connection from battery to frame. If you did so run, and turned your lights on, your generator would deliver current direct to the lights, there being no path through the battery circuit. The generator current, after passing through the filaments, would earth via the metal of the bulbs, and go straight back to the generator by frame. Those said filaments would go out—literally—in a flash.
You remember that in the old-style Ford the lights used to go up and down according to the speed of the engine. That was because the. voltage of the magneto current was always varying with engine speed. Really, it was very: difficult to choose a bulb that would stand up against that kind of varying strain. If you got a bulb that was strong enough to take the highest voltage produced when the engine was running at top speed, you got a poor light on average speeds; and if you chose a bulb that was weak enough to give a good light on slow speeds, you found it bum. out atshigh speeds. You had to compromise—and it was not eossible to get a good compromise. That is why old-model bulbs burnt out so much more often than new-model bulbs.
By the way, if your bulbs do burn out too readily, you ought by this time to know the remedy. Get a higher voltage bulb—not a lot higher,', but, say, a couple of volts higher. This is the remedy in the case of the old model. With everything in order, on the new model you cannot get more than 8 volts at the outside, however good the condition of your C32 battery, so that 6-8 volt lamps are what you want, and they stand up perfectly.
The trouble will .come on the new model if your battery gets down, and is not up to even 6-volt form. Then your filam-ents will glow red, because there is so little current to resist.
436.—Magneto Troubles.
, The magneto is often unjustly suspected of causing trouble. It is very rarely, indeed, that it fails. In practically every case ignition failure is caused by something outside the magneto. Here are, however, a few tests for a suspected magneto:— a) To be used on a new model Ford, with battery installed.—Run the engine on the battery current, after removing the wire from the magneto terminal. From that terminal run a wire to some point of the engine or frame where a clean contact can be made. Make the contact with the free end of this experimental wire, then null the wire away from the metal. At each break of the contact snappy sparks, should appear if the magneto is working properly. (These sparks are better seen in the dark.) (2) To be used on an old model Ford, without battery.—If ignition is faulty and the headlights do not glow, properly, or at all, the magneto is suspect. Remember, however, that a fault in the wire running from the magneto may cause trouble, independently of the magneto itself. (3) If ignition is faulty on magneto current, but improves when the hack end of the van is jacked up, the probability is that the flywheel is loose, so that the magnets stand too far away from the stator coils on the level. The tilting has thrown the magnets forward to their proper distance ; hence the improvement in the ignition,
(4) if the ignition on magneto current is faulty when slow-speed is in, (and only then), this also smay be, slue to looseness of the flywheel ;because the thrust of the clutch tends to drive the flywheel back, and so to increase the distance between magnets and stator coils. Remember that a foul magneto contact assembly will probably affect the output of the magneto unfavourably. If the magneto current is proved by any of the above tests to be poor or nil, clean the magneto contact assembly first.