IDEAS ABOUT IGNITION.
Page 31
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Useful Tips from Our Driver and Mechanic Readers.
A VERY thorough method of clean
ing out accumulators is described by "H.H.," of Highgate. He had, he tells us, a six-volt set which had been allowed to get into rather a bad condition, the plates being thickly sulphated.
As a preliminary the cells were turned upside down in the sink to let the acid out. While that was going on, our correspondent drilled three holes, one in each cell, close to the strengthening ribs; the holes were i-in. diameter. Turning the battery right side up again, the cells were next well sluiced out with water, each cell being treated in turn, the tap being turned wide open and the water flowing at full pressure. The stoppers were then replaced, and ,the battery turned upside down again, to be filled with warm soda-water, which was poured in through the drilled holes. After letting them stand for a while they were again stood upright, and once more submitted to the ordeal of cold water. By this time they had been practically cleansed of sulphate, and the next job was that of sealing up the drilled holes. This was effected in the following manner:— A piece of celluloid was procured, and three square patches, each about 1 in. across, were cut from it. A piece of the celluloid was scraped with a knife, until a nice little pile of shavings had been obtained. They were damped with • amyl-acetate, until they took the form of a soft jelly. This was used as a paste to secure the patches, which had to he left for half a day (12 hours) after fixing.
Finally, each cell was carefully filled with fresh acid, and subsequently charged slowly.
A SIMPLE type of rain cap for a
sparking plug is described by "W.S.R.," of Belfast. It is made from the brass socket of an old incandescent. electric lamp. The interior insulating material must first be removed, and the top covered in by means of a copper or brass disc, which should be soldered in place. Drill a hole through the centre of the disc, and slip it, over the plug terminal under the h.-t. lead.
THE difficulty with a good many oil indicators of the type which is fitted in the dash is that they are invisible in the dark. This is a matter which only arises in connection with commercialmotor vehicles, which are not equipped with dashboard lights and other luxuri ous fittings which are now a standard feature on touring ears. If the lorry driver has much night driving to do he is compelled to put his hand to the indicator again and again, to reassure himself that all is well. That is to say, he utilizes his sense of touch in cases where it, can be of service, which happens when the oil indicator is of the plunger type, in which the plunger projects from its casing when all is well with the lubrication system.
Now, it is not always convenient to follow this proceeding, apart from the fact that a man may very well be excused for forgetting the operation, and his forgetfulness may come at a critical moment—it generally does—and we are the more indebted to W.C.S.," of Sunderland, therefore, for his description of a simple means of fitting one of these plunger indicators with an electrical apparatus designed automatically to switch off in the event of the plunger falling.
The apparatus is plainly illustrated by the accompanying sketch, in which 1 is a brass bar soldered to the top of the plunger, 2 is a brass plate, mounted on a vulcanite insulating block (3), and wired up to the switch terminal on the magneto by 1.-t. lead (5). The body of the plunger is earthed by wire (6), which connects it to the earth wire in the switch. It will readily be understood that when the plunger falls, which it will in the event of the oil pressure dropping, 1 contacts with 2, earthing the 1.-t. current of the magneto and preventing ignition.
As there is no pressure in the oil pipes at starting, some special means of holding the plunger contact (1) off the plate (2) must be devised. This is shown at 4,
,which is a turn-button, this being in the vertical position holds them apart. It should be set in that position for starting, and when the oil is flowing freely should be turned into the horizontal position indicated at A.
THE first correspondent sends us more useful hints in connection with the uses, and abuses, of "spark intensifiers." These are, he remarks, too often condemned because too much is claimed for them, and too much expected of them. They are, in his opinion, only likely to be really beneficial in connection with engines which are apt to oil up easily, and even then only if the magneto or other ignition equipment ia not so efficient as it might be.
The construction and the principle on which these gadgets work are alike simple and easy to follow. The gap is embodied in a contrivance in which the h.-t. wire is broken, and the ends separated by a distance of not more than 1-16 in. The current, on its way to the plug, must jump this gap, and the theory is that the gap acts in some way as a dam, holding back the current, which piles itself up behind the gap until it is
strong i enough to jump it; the extra intensity thus obtained s carried, as it were, by its own momentum, to the points of the plug, where it causes a hotter spark than would occur if the gap were not provided. This hotter spark doe l not, of itself, improve the combustion of the gases, but it burns away any oil which may tend to rest upon the points of the plug.
Some drivers, when endeavouring to clean a plug which is known to be oily, remove the high-tension lead from the plug terminal, and hold it a short distance from the plug, thus providing a temporary spark gap, which has the same effect. , It is important, in all cases, to see that the gap does not exceed 1-16 in., as a larger space imposes a heavy strain on the magneto and may even do serious harm, especially if there is no safety gap on the magneto. This is a point which should always be borne in mind when making a temporary intensifying gap in the manner indicated.