Contributions from Drivers and Mechanics.
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TEN SHILLINGS WEEKLY for the Best Communication Received, and One Penny a Line of ten words for any thing else published.
Drivers of commercial-motor vehicles curl tractors, and mechanics and foremen of garages or shops, are invited to send short contributions on any subject which is likely to prove of interest to our readers. Workshop tips and smart repairs; long and successful runs ; interesting fili.dogralhs : all are suitable subjects. Send a post-card, or a letter, or a sketch to us—no matter how short,er how written, or how worded. We will "knock it into shape" and prepare sketches, where necessary, before publication. The absence of a sketch does not disqualify for a prize. When writing hse one side of the paper only and mention your employer's mime as a guarantee of bona fides. Neither your own ncr your employer's name will be disclosed. Payment will be made imme&early after pull, (—rum. Address your letters to The Editor, THE COMMEIZC1AL Moroa, 7 15, Rosthery Avenue, London, E.C.
A Tourniquet on a Chain.
The sender of the following communication has been awarded the 10s. prize this week.
[613] " J.S.I." (Coventry) sends a note with regard to a simple method of joining a driving chain.—' Please find enclosed a rough sketch of a rope tourniquet, which is, as your readers will know, a very old-fashioned device. I do not think, however, it is often used for the purpose to which I have adapted it. I refer to the pulling together of the two ends of a driving chain, in order to insert the coupling bolt. I, of course, know quite well that the correct method to adopt is to get the joint of the chain on to the large sprocket, so that the teeth of the wheel will hold it in position, but it is frequently the case that these teeth are so much worn that they then allow sufficient end play in the chain to prevent the bolt-holes coming into anything like correct line. Any subsetvient adjustment must he snack, w it Ii 6he radius red, and this is very often a very troublesome job. In many shops, of course, small speciallymade clamps are employed, but I think you will agree that the method I have outlined is quite a good one and could be adopted in all kinds of emergencies where a special tool is not available. I have sometimes found it to be of the greatest service out on the road when a chain is broken. Of course, the device is as old as the hills. but I think its application is novel,"
Two Tips from a Tractor Driver.
[614] " (Lewisham) writes as follows.-In the course of my travels as the driver of a tractor. I have often had trouble with gauge cocks' and cylinder taps' blowing badly. Very often it happens that a drivesrennet find the time to grind them in properly for a while. In such a case, a good tip is to get a pieee of red indiarubber, to melt itover the gas and to spread it very
thin over the various plug fittings that are blowing. I find that, so long as you don't open the faulty cock while it is cold, this method of treatment will keep the job steam-tight for weeks. While the. cock is hot there ii no danger in opening it.
" Another tip I have found to answer is the following. When the brakes on a steam-wagon or tractor will not hold a load back while going down hill, if the brake block, are of wood and the drum of cast-iron, the best thing to use is some fine coal-dust. This will hold any brake, howevery slippery it may have been before."
One Way to Start an Engine. Locating the Position of a Piston from the Inlet Valve.
[615] " X.Y.X." (Dartford) is responsible for the letter which we publish below :—" As, in the course of my business, T have almost every kind of breakdown to attend to from time to time, I read your paper, and especially the contributions from drivers and mechanics, with very great interest. I notice that one of your correspondents recently sent in an account of how he had to start an engine without a starting handle at 2.30 in the morning, and without any tools. I, in no way, want to say anything against the manner in which he states he got over the difficulty, but I would like to tell him of an easier way than the one he adopted. I imagine that, if his car and engine were as he states, in no way amiss, he must have got some distance up the hill before it became necessary for him to change into a lower gear. Then, finding that his engine stopped, his first instinct would have been to apply Isis brakes and to dismount in order to start his engine. When he found that his starting handle was out of action, if he had mounted his seat, and put his gears in reverse, holding his clutch out the while, and had then allowed his car to run back down the hill, he would have gained sufficient impetus to allow him to put in his clutch and so to get a turn or two on the engine. He could
• then have stopped the vehicle, changed into forward gear, and gone for the hill again. Supposing, at the bottom of the hill, he had not succeeded in starting his engine, and presuming that his ignition was coil-andaccumulator, if he had opened his throttle to the full extent, advanced his ignition a little, and then turned the (dutch round with his hand, as soon as the first cylinder got over the top of the compression stroke it should have fired and started the engine. If, however, the engine was magneto-fitted—especiany low-tension—his task must have been a hard one I, personally, have had motorbuses jacked op and found it hard enough to turn the wheels with the gears in neutral; it must certainly be nothin, less than slavery to do so, when the gears are in mesh and driving the engine. You certainly have to get a considerable amount of speed on to a magnoto-driveu engine in order to get it to start, and, in my opinion, it is doubtful whether it would normally be possible to turn the wheels under the conditions stated."
"Another of your readers mentions candle grease as an insulation. If he had happened to have the vulcanized mouthpiece of a pipe or some sealing wax, ho could have run either of these in a melted condition on to the faulty insulation and made the job as good as new—certainly a better job than the candle grease.
"A simple method of locating the position of the piston is the following, which I generally adopt. I recently had occasion to take the high-tension magneto off a wellknown make of engine, and, when I went to replace it, had to find a way to ascertain the dead centre before the firing stroke in order to time it correctly, as there were no compression taps on this type of engine through which I could put a rod in the usual way. I might mention that I have found this to be a puzzle to many an experienced man when the engine is not fitted with overhead taps. At any rate, I first turned the handle round until the exhaust valve was just closing and the inlet was just opening. As I find that nearly all inlet valves open about two or three millimetres down the stroke. I knew that this was not far from the top centre. I then marked this position, from the starting handle, on to the radiator with a piece of chalk, as carefully as possible, and next gave the engine a complete revolution, knowing that this would bring ma to the top centre again. As this is the end of the (Impression stroke, I found this was near enough to set my magneto, at any rate for a trial run with the engine. Where it is impossible definitely to indicate the end of the stroke, this means of getting at it from the inlet valve is. as a rule, sufficiently accurate to htnrt with. The only trouble that is likely to occur is when the valve lifters are worn or badly adjusted to any extent." rOur correspondent should remember, with reference to the first part of his letter, that when the low-forward or the reverse gear is in operation the engine would be "geared tip" cqnsiderably with regard to the road wheel,; it is quite possible to pull the whole car up under such circumstances. It lean easy matter, of course, to start the engine in a similar way with the gear in top speed and the ear running forward.—ED.1
"On"ICCold and Frosty Morning."
[5/331 " FI,M." (Darlaston) sends a few notes of advice for drivers during frosty weather.—" I think it is pretty well known that the effect of frost and low temperature upon metal generally is that it renders it more brittle than usual, and, frequently, fractures occur in cold weather, very largely from this cause, without any warning. It is most important that every part of a steam tractor or other heavy motor should be well warmed and thawed before it is submitted to bad shocks, such as those frequently encountered in the ordinary course of events on the road. I remember, a few years ago, a small traction engine was left in a field aIl one night during which there was a severe frost, and the next morning, when men were sent to fetch it in, steam was got up quickly and the tractor was started away in rather a hurry, with the result that the crankshaft broke at the bend near the crank pin, at the first turn. I put this down entirely to the effect of the low temperature on the metal. I have frequently seen the iron-work on railway coal-trucks snap like glass on a frosty morning directly any attempt has been made to move the wagon. The need for care in the matter I have mentioned is illustrated by the fact that, when a cast spanner, steel turning tools, or drills are accidentally dropped on a hard floor on a frosty morning, they very often fall to pieces; chains frequently break at half their normal load when there is frost in the air. It is therefore of the most vital importance in my opinion for drivers to realize that their draw gear, brake gear and other such parts should not be worked until some attempt has been made to warm the whole engine up to a certain extent. Of course, the great thing to do is to see that everything is carefully housed at night-time when the machine is not at work. If this be not possible, tarpaulins and mattings should be employed, and then very careful warming up when the vehicle is again wanted."