The Drivers' Page.
Page 16
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Various Ignition Systems.
A.1I.13, writes :-" The following hints on ignition will be useful to the novice who has only a slight knowledge of the different systems in use, although to the driver who has thoroughly mastered the principles it is generally only the work of a few minutes to locate and repair the fault. There are three general types of electric ignition now in everyday use :.—(1) That known as accumulator high tension; (2) high-tension magneto; and (3) low-tension magneto, The first system is in very general use, and is reliable in work!ng; a point in its favour is the command which the driver has over the advance and retarding of the spark. 1Vith both the magneto systems, although the makers lit mechanism for the purpose, no appreciable advancemera of the spark is possible; this means that Lamsiderable power is lost.
" An accumulator, if properly looked after, is a most reliable carrier of electrical energy; careful and regular charging are the two most important points to be remembered to obtain efficient working, and it is extremely bad policy to over-discharge them when in use. Directly the voltage falls below four for any two cells, recharge till on connecting up to a voltmeter it shows +.5 volts. Always have the accumulators Lightly packed in the box which carries them, as the continued jolting, besides splashing acid on to the terminals and corroding them, is liable to detach the paste from the grids and cause internal short circuiting. 'Vaseline is the best preventive for corroded terminals, which should be scraped quite clean and bright with a penknife or line emery paper, and then smeared with a good thick coat of it. Sulphating of the plates is produced by charging too quickly, or by over-discharging and then leaving idle for too long a time; it can generally be cured by sending a low voltage through the plates for a lengthened period. Never connect up an ammeter directly to the terminal screws, as this produces a short circuit which, in all probability, will buckle the plates. As to the coil, the only parts that 11Ced any adjustment are the trembler blades; these in time become pitted, which is not only wasteful of current, but will cause misfiring. The best way to trim the tremblers is to flatten them by striking with a light hammer, or a fine file may be used if they are very badly fitted. On many coils the terminals are not enclosed, and these, especially when fixed on the dashboard, should be covered with short lengths of indiarubber tubing, slipped over the ends of the wires and worked on Lo the terminals after the wire has been fixed; this does away with the possibility of leakage in wet weather. The general tendency is to screw down the trembler screws too far; they should only just make tirm contact, but no more, and should then vibrate slightly on tap-. ping the coil box. Also, always make sure that there arc lock nuts on the screws, or they will require frequent adjustment through slacking back. Adjust all the tremblers on a coil as evenly as possible to secure equal running from the engine cylinders. Some modern coils are fitted with only one trembler, and this gets over the difficulty, and adjustment is reduced to a minimum. " The wipe type of contact breaker seems to be used more than any other, and in its present form it is reliable, and requires practically no adjustment, but it is not suited to every type of engine. The use of oil on the commutator should be avoided as far as possible, as this tends to accumulate dirt and grit, causing bad contact and misfiring.
." Clean sparking plugs are of vital importance to the efficient running of an engine, and the best way to clean them when sooted up with burnt oil is as follows :—First immerse time plug in a can of petrel, shaking the plug about for a few minutes, then wipe thoroughly; again dip the whole plug into petrol, then place on a stone floor and apply a lighted match; allow all the petrol to burn off, and when cold wipe again thoroughly, and the plug should be perfectly clean and the porcelain white. A tooth-brush and petrol, or emery cloth, is also useful. When trimming up the points of a sparking plug, the points should be filed quite flat, which tends to make a ' fat ' spark. Always use terminals on the ends of wires; the hooked variety are the most useful, especially for sparking plugs, as they can be detached by half a turn of the binding nut. The ordinary flat terminal with a hole in it may easily be converted into this type by slotting the hole right to the edge. Trouble is sometimes experienced through frequent breaking of plugs. This, in many cases, can be traced to either the wires on to the plugs being too short or to the wire not being flexible enough. In the latter case the insulation should be pared down with a knife, or entirely stripped off for about six inches, and the wire then carefully bound with insulated tape. In the high-tension magneto system the magneto simply plays the part of the accumulator and generates the primary current, which is collected and then carried by a wire to the induction coil, a rotating distributor controlling the suppiy of electricity to each cylinder. This system works extremely well, hut is not largely used, its chief drawback being the difficulty of getting a full range of retard and advance on the spark. The low-tension magneto system is, perhaps, the most simple, as it necessitates only one wire. Ihie current is produced by rotating an armature in a magnetic field; the spark is then produced by a device whim inakes and breaks the circuit inside the cylinder. The thief disadvantage of this system is the loss of compression which occurs at the point where the rod working the make and I reale tappets enters the cylinder. The igniters very rarely require attention; they occasionally require filing flat as the tappet begins to wear. With this type of ignition the same difficulty is experienced with regard to the spark advance as in the high-tension system. Always see that the tappet springs are sufficiently strong to ensure a quick breaking of the circuit ; they sometimes lose temper and become soft.'
A Boiler Makeshift.
G. \V. (Sunderland) writes :—" Some time ago, whilst driving my steam lorry, which has a water tube boiler, I had the bad luck to have two tubes burst at the same moment. I took the cover of the boiler off and then set to work to cut out the broken remains, which I found a rather awkward job, having no really proper tools to work with. This done, I looked over the wagon and selected four squareheaded bolts and nuts, taking them from the most unimportant parts of the framework. I then took one of the bolts, and managed, after some difficulty, to get it sideways through the circular tube hole, then I pulled it straight, causing the four corners of the square head to catch. I then slipped an asbestos washer on, with an iron washer over it, then screwed the nut on top of all. The other three bolts were attached in a similar manner, after which I filled the boiler with water, and worked home on half the usual head of steam." See page 274 for award.