Nom Drivers &Mechanics TEN SHILLINGS WEEKLY is paid for the
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Light Up Your Lamps At 8.29, ThurscLay ; 8.30, Friday ; 8.32, Saturday ; 8.35, Monday ; 8.37, Tuesday ; 8.39, Wednesday.
Keep Your Silencer Clean.
[1469] " L.H." (Birkenhead) writes :—" Periodical cleaning of the silencer plays a more important part in securing engine efficiency than is generally realized. This adjunct to an engine is often neglected to such an extent that many of the holes in the baffle
plates become completely stopped up, and the others are often so choked with carbon deposit that the power of the engine may be considerably decreased owing to the back-pressure set up. Numerous troubles are liable to occur through this fault, such as overheating, etc.
"The reason forInianvqsilencers being neglected is that their construction does not usually admit of their being readily cleaned. The ends are often riyeted right into the casing, and it is impossible to get at the baffle-plates without a great deal of trouble..
"I enclose a sketch [We have had this redrawn.— ED.] of an improvement which I carried out to the silencer of the vehicle which I drive. It was of the type I have just described, in which both ends were permanently riveted. Each end was originally fitted with a centre-stud for the purpose of supporting the silencer in brackets. These studs were removed and the holes opened out until a piece of mild-steel, the same diameter as the studs, would just slide through them.
"I removed one of the ends by knocking out the rivets and drilled a hole through the centre of each of the baffle-plates, of the same diameter as the mildsteel bar. The rod was cut off to a sufficient length to pass right through the silencer and project at each end to the same amount as did the original studs. It was screwed at either end for some little distance, and, after being pushed through the fixed end of the silencer, was lacked in position by a couple of nuts. "The baffles were then replaced, and also the loose end-plate, which was firmly locked in position by two E2 nuts at the other end of the rod. To clean the silencer, it is only necessary to take off the nut on the outside of the fixed plate and to tap this end of the rod on the floor, when the loose plate of the silencer will come out, and the baffle-plates can then be easily. removed. If necessary, the tie-rod can be screwed throughout its length, so that each baffle-plate can also be locked in position by nuts."
A Simple Removing Tool for Diagonally-split Piston Rings.
The sender of the following communication. has been awarded the las. prize this week.
[1490] " J.0.11." (Bristol) writes :—" It is quite a simple matter to make a piston -ring removing-tool for rings which are split vertically, and the one described by G.W.E.' (letter No. 1455) will do this work quite vs.311, but the writer of that letter admits that his particular device will not do if the rings are cut diagonally. Now my experience is that almost 75 per cent. d piston rings are so split, and, in order to cope with their removal when overhauling an engine, I constructed a tool somewhat similar to the one described by G.W.E.,' the chief alterations being in the ends which engage the rings. "I enclose a sketch [We have had this redrawn.— ED.] of the device. It is made from two pieces of mild-steel ; in. by 4 in. section and 7 ins. long. The joint holes are drilled about 2 ins, from one end of each bar, and the handle portion is rounded, either by means of a file or in a lathe. The opposite ends are filed down in the manner shown, the groove in each having one vertical side, while the other slopes upwards at an angle of 45 degrees. The lowest portion of the slots reaches within -,1E in. from the bottom of each end, both pieces being made the same, as, when reversed in assembling, they fit the ring in the required manner. The metal at each end is cut back from the slotted portion, allowing a projection of about in. The tool can be finished off with a spring and adjuzting-screw in the same manner as has been previously described by G.W.E.'
"In using the tool, the ring to be removed is pushed
into the piston groove, at the opposite side to the split. The tool is then inserted between the ends of the ring, which are kept from sliding off by the corner of each catching in the V-shaped slots of the device.
"Although the tool may not seem to be of strong construction, it will suit quite well for ordinary work, as the pressure required is only very light."
R mewing the Life of Piston Rings.
[1491] " G.W.E." (Thornton Heath) writes :—" A very common workshop practice for restoring compression to engine cylinders is to grind in the piston rings with fine emery, so as to obtain a good fit between them and, the cylinder wall. In some instances, however, a portion of the ring may be found to stand clear of the cylinder, and it is usually quite obvious that no small amount of grinding will be required to correct the defect, and if time be spent in doing this grinding, very often the ring will he found to have worn so much that almost tl1 its spring has been eliminated.
" The following tip is one which I have frequently pat into practice in such circumstances, and very good results have been achieved by its use, as it has saved the expense of new piston rings in quite a. number of engines. The defective ring should be removed from its piston, and should be held on a block of wood with the split uppermost. The ring should then be tapped gently on its inner surface with the ball end of a
ti mail hammer, the blows being graduated so that the heavier ones take effect opposite the split, and the least heavy at the ends near to it. Of course, in order to do this' the ring has to be turned round gradually on the block.
" If ordinary care is exercised, quite a good circumferential fit will be obtained, and after trying the ring in the cylinder this fit may be further improved, if necessary, by the use of a small fiat file before the grinding-in process is resorted to. "The method gives a considerable amount of extra spring to the rings, and even when they are a fairly good fit in the cylinder, should they be much worn, it may be found advantageous to use this method for giving them the required extra amount of spring."
Novel Repair to a Cracked Piston.
[1492] " A.C.P." (Loughborough) writes :—" The engine on the vehicle I drive recently gave trouble owing to one of the pistons cracking through, the fracture occurring in the centre of the top-plate. When my employers wired for a replacement, the makers of the engine said they were waiting for piston castings themselves, and could not, therefore, dispatch renewals before at least a week.
"It being necessary to get the vehicle running immediately, I took the piston to a local engineering works, and had the following repair carried out. "The top plate was bored out. and screwed 2 ins, diameter, with a finely-pitched thread. Into this hole a mild-steel plug was tightly screwed, red lead being used to make a good joint. The ping used had a large-diameter flange, which, on being screwed down, came tightly on to the top of the piston, sufficient depth of the threaded portion being provided to allow the plug to project a short distance inside the piston. This projecting portion was then suitably faced off, leaving a email edge all round for riveting-over purposes. To prevent, any possibility of pre-ignition, the edge of the outer flange was chamfered off. " When refitted in the engine the piston gave no trouble whatever, and would, no doubt, have lasted as long as the new one, for which it was eventually changed. The makers had realized that their original piston design was somewhat on the light side, and the new piston proved to be of a slightly heavier design."
A Centring Plate for Bar Work.
[1493] " G.T." (Ilyde) writes :—" During my work as a turner, I often have to centre small odd pieces of steel and gunmetal bar for making into small
spindles, gudgeon pins, bushes, etc., and I found that i time was wasted n centring-up in the usual manner. I therefore made a guide-plate which has since saved me quite an appreciable amount of time.
"I enclose a sketch [We have had this redrawn.— En.] of the device; it consists of a piece of flat bareteel, 1 ft. long, tin, wide, and -4. in. thick. Along the 1-in. face I made 22 centre-punch marks at equal distances. I then drilled holes at each mark, beginning with a, drill which was equal in diameter to the smallest size of bar which I use, and continuing with each hole one-sixty-fourth of an inch larger than the previous one. These holes were not drilled right through the plate, about A. in. thickness of the metal, or slightly more, being left at the point of the drill ; the portion left at each hole has afterwards to be drilled right through with an k in. drill.
" To use the plate, the workpiece to be'eentred is held in the vice and the requisite hole in the plate placed over it. A special centre-punch, with a reduced point, is then placed through the e in, hole in the plate to touch the bar, and a light blow on this is sufficient to centre-mark the rod quite accurately."
All the Valve Springs Should Give Equal Pressure.
[1494] "M.A.S." (Finsbury) writes :—" In. order to get the best running out of the engine of any petrol vehicle, it is essential that all the valve-springs he of as uniform strength as possible, and they should be periodically tested in order to see that they confored to this condition.
" A simple way of making comparative tests is. to press each spring in turn on the scale of a weighing machine—preferably of the spring type. This should be done until the valve-spring is compressed to about twice as much as it would be normally. The reading of the balance should be taken, and any springs which do not come up to the average should he either scrapped or, if not too bad, packing washers may be placed between them and the valve-spring washer until the springs give the necessary pressure."