The Motor Drivers News.
Page 27
If you've noticed an error in this article please click here to report it so we can fix it.
A Broken Piston.
" J.B." (Cricklewood) wishes this lettei. to appear in the "Drivers News " :—" Perhaps the following experience may be of interest to other drivers?
"A fortnight ago, I was in charge of a 4oh.p. -motorbus, which contracted a peculiar knocking, at short intervals, in some part of the engine. As the motor was pulling ' very well, I made up my mind that the noise was caused through the sparking being unduly advanced, probably owing to the timing wheels being incorrectly meshed when being put in position. At my journey's end, I had a look at the ignition details and found, rather to my astonishment, that they appeared all right. The question was, where was the trouble located? The next thing I did was to take off the inspection doors, so that I could examine the big-ends ' for any undue slackness. I first looked at Nos. '3 and 4,' and found them in good order. Then, I had a try at Nos.'i ' and '2,' and found that these were also in proper running condition, but I noticed that there were some small pieces of metal adhering to the brasses. I made a further inspection of the crank-chamber, and found that the bottom of it was covered with small pieces of cast-iron. This was a serious condition of things, and I then put my hand up Nos. ' and ' 2 cylinders, and found that the piston in the latter was completely shattered. The whole thing is a mystery to me, and I cannot understand how the engine 'pulled' as it did under such adverse circumstances. It only shows what a petrol engine can do even when badly damaged."
Brain versus Muscle.
" T.B." (Lampeter) sends the following letter :—" A great deal of carelessness is sometimes shown in the fitting of new sparking plugs to petrol engines. I have ieen broken plugs taken out by one or two unskilled men and replaced with a new one which happened to be a tight fit. Nothing like muscle ' appears to be the motto of a certain class, and I have occasionally watched a driver screw a new plug 'home' with a large pair of pipe tongs, and thought to myself, at the time, that he would have a pretty hard tussle to get it out again when replacement was necessary. Sometimes new plugs of the same thread as that in the combustion head are rather tight near the shoulder, and it is a great mistake to force them into position, because in nearly all cases the asbestos-lined copper washer is not properly compressed and a mysterious loss of compression takes place which may be somewhat difficult to account for. Always try a new plug in position before slipping on the washer, and then remove the plug and screw it finally " home " with the washer in position. If the screw thread is too tight, go round it with a fine three-cornered file until it fits properly. Plugs and such-like small details of the engine should invariably be fitted in position in the depot, and then replaced in the tool box upon the vehicle in readiness for the time when they may be required. It will save time, and money, if the strength of the muscles is leavened with a modicum of brain, when doing small jobs. Only the other day, I saw a man screwing up the gland of the spindle belonging to a water-circulating pump as if he had a personal grudge against it. At the finish, he remarked to his mate That's got it, Bill.' It had got it with a vengeance, because when the engine had only been running for a few minutes the spindle broke off short like a carrot. Another example of muscle versus brains. Threads are frequently stripped' when screwing up nuts, because the knack of feeling when a nut is screwed up sufficiently tightly has not been acquired. Result : loss of time, money, and temper." How to Keep Brakes in Good Order.
" T. H. " (Leamington) writes to us on the t8th instant :— " I should like to write a few words about brakes on steam wagons. I always take care to see that the blocks which form the brake upon the back wheels of my wagon are in good order. I notice in my travels that this is not always the case. Many drivers rely upon the reversing lever for emergencies, and allow the legitimate brake to become useless, from want of proper attention. No greater mistake could be made than the foregoing. The three points to observe for keeping the brakes in an efficient state are :— " (I) Renew the brake blocks when they are worn. " (2) Oil the operating screw frequently. "(ti) See that the pins and joints are in good order.
" I find it saves trouble, and keeps the steering-gear joints clean, if they are fitted with canvas or leather covers."
Care of Safety Valves.
" T.D." (Keighley) writes :—" A few days ago, a steamwagon driver drew my attention to the safety valve on his boiler, as this refused to act in unison with the steam gauge ; he told me that he had tried two new steam gauges, with the same result. It was a well-known make of boiler and the two safety valves were held in position by a T-lever, and a spiral spring. After a few seconds' examination, I saw the cause of the trouble. Credit was due to the driver for cleanliness but, in painting round the safety valves, he had allowed the paint to accumulate between the spirals of the spring, so that it (the spring) became one solid mass of steel and paint, thus causing more strain on the valves as the valve spring was not able to compress. The driver proposed to burn the paint off to clean the spring, but I explained that to burn the spring would take the temper °tit of it. 1 cleaned it for him with my knife, and advised him to black it with plumbago, and afterwards polish with a brush, particular care being taken to keep the spaces between the coils of the spiral spring clean, and free from accumulations, by running string through them. " In case of a safety valve not blowing off at the registered pressure, a slight tap with the hand may relieve it. If the foregoing fails, keep the engine running as fast as possible, but, if the water level is low, start the injector to work and close the dampers. If considered necessary, damp down, or choke the fire with wet ashes. Do not tamper with the safety valves with steam up. "Do not blow off the boiler by knocking a mud lid off. I have known this done with serious consequences. Blow off at the proper place, viz., the sludge cock. "Priming at safety valves will cause them to become partially choked. The valves require cleaning after such an occurrence. When a boiler primes, close the regulator valve, find the true level of water, and open the cylinder relief taps. If the boiler is too full, open the sludge cock for a few seconds and allow the water to be drawn onethird of the distance down the glass. Close the sludge cock, and then make a fresh start. If the priming is allowed to continue, the slide-valve faces, cylinders, and piston rings will be scored. In boilers where the steam space is small, regularity of firing and water supply is necessary. Priming results from various causes ; some boiler liquids, sold to remove encrustation, will cause priming. Introduction of oatmeal or bran, with the object of stopping the leakage of tubes, will, also, cause priming. Do not attempt to stop priming by the introduction of liquid oils, as most of these develop fatty acids which are very injurious to the boiler."