For DRIVERS, MECHANICS & FOREMEN.
Page 21
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A PRIZE OF TEN S.ELILLINGS is awarded each week all others are paid for at the rate of a penny a line, with an published. Mention your employer's name, in confidence, Commercial Motor," 7-15, Ro
Lamps Alight.
On Saturday, July 5th, light your lamps at 9,47 in London, 10.59 in Edinburgh, 10.16 in Newcastle, 10.12 in Liverpool, 10.1 in Birmingham, 9.57 in Bristol, and 10.55 in Dublin.
Stationary Engine Troubles.
The sender of the following. communication has been awarded the 1,0s. prize this week.
[1,969] " G.J.J." (Worcester) writes :—"Since I have been demobilized I have been a constant 'reader of The Commercial Motor, and I am most interested in the page 'For Drivers, Mechanics and Foremen.' "Although during the time I was in France in the Royal Engineers I did not drive motorcars much of my work was on stationary engines and -petrol tractors. That being 130, the following wrinkles may be considered suitable for insertion.
"I had charge of several four-cylinder 26 h.p. petrol engines of a well-known make. These engines stood up remarkably well on hard, continuous sawmill work
and were never cleaned until absolutely necessary. The great difficulty experienced in removing the valve caps—which were often badly knOcked about— was no doubt attributable to this neglect. To overcome this difficulty I used a two-ended wrench, with a circular hale in each end just large enough to take the body of an old sparking plug and broken priming cock respectively, but. not large enough to allow either to slip through. A thick metal washer was tightly driven 'ori to the plug and another on to the cock from the underside, the -washers were prevented from coming off by the hexagon head of plug and the body of cock.
"To remove a stubborn valve cap all one had to do was to remove plug or cock, place wrench in position on cap, screw home the plug and washer through the hole in wrench, and you could hammer away at the wrench as hard as you liked without damage to valve cap.
On these same engines the magneto was driven off a small shaft through a worm drive at right angles to the camshaft. As occasionally-an engine was taken down for a complete overhaul it was a difficult matter to get the timing correct the first time on reassembling owing to the fact that the magneto driving shaft was fitted into the timing gear cover. To remedy this I stamped a large T on the crankshaft against the starting handle. This T when at the top showed that No. I piston was at the top of compression stroke. Before dismantling the engine I cranked round until T was at the top, then, after removing magneto, I scribed an arrow-beaded line on the end of the magneto driving shaft and on the gear cover centre mulched a dot exactly in line with this arrow. to the sender of the best letter which we publish on this page ; allowance for photographs. All notes are edited before being as eviden.ce of good faith. Address, a, M. and F., "The sebery Avenue, London, E.C. 1.
On drawing the gear cover gently away the shaft travelled round a little. Two marks on cover marked the amount of travel. To reassemble, T would be turned to the top, the arrow placed in line with the two dots and the cover refixed in position. The position of the arrow in relation to the one dot served as a check on the correct position."
The Use of a Crankcase Breather.
• [1,990] " LI.J.0." (Battersea) writes :—" This letter concerns quite a email matter, but one which, in my opinion, is worthy of more attention than it usually receives. _Quite recently I had to deal with an engine which, it was claimed, coneurned a large amount of oil, and did not deliver anything like the power which it was supposed to develop,
"When I lifted up the bonnet, I must say I met with a surprise. I never saw such a dirty oily engine in all my life: it was simply covered with grease, from valve caps to crankcase drain tap. I started up the engine, and watched operations. It simply as it were, exuded oil from every pere. Then I accelerated a little in order to discover the worst places where leakage occurred.found that it was blowing-.out of the tappet guies, and everywhere where there was a chance for it to get out. I therefore came to the conclusion that there must be considerable pressure irfside the case for this to occur. I next had a look at the creekcase breather, and put a lighted candle to it, naturally expecting it to be blown out. Nothing happened. I then looked inside this useful accessory and discovered that someOne had corked it up and put the cover on. This of course, accounted for the trouble. I removed the offending breather, and, after taking out the cork, deemed it and replaced it. I got some old petrol and a brush, and thoroughly swilled and cleaned doevii the engine, wiped. it dry, went over all the nuts of the crankcase to make sure that everything was tight, and then started the -vehicle up. It ran at all speeds without oil escaping from anywhere. I put the candle to the breather, and this time it was
blown out immediately.
"A lighted candle to the breather tells more than merely if it is stopped up with a cork.. I use these adjuncts, for example, to discover if the Piston rings are in good order. Put a -lighted candle to the breather, and turn the engine round by hand, If the flame of the candle moves periodically towards and away from the breather, it may generally he assumed that the rings are all right, or, at any rate, that they are not in such a poor condition as to warrant taking down the engine and replacing them. If, on the _compression stroke, however, the flame is blown away from the breather, that is a good indication that there is a -considerable leakage past the rings, and that they should be renewed.
Take Care of Your Accumulators.
[1,991] "M.J." (Richmond) writes : "Nothing is more ruinous to the plates of an accumulator than overcharging. A useful rule which I have found to work well in practice is to charge with a current of I amp. -during 10 hours for every 20 sq. ins, of positive plate surface. If the accumulators are to be charged from a continuous current supply of, say, 220 volts, each side of an ordinary switch may be connected to a series of seven 16 c.p. lamps and thence to the accumulators. The polarity must, of course, be de
termined."