Contributions from Drivers and Mechanics.
Page 21
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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 vehic is and tractors, and mechanics and foremen of garages or shops, arc invited to send short contributions on any subject which is likely to prove of interest to oar readers. Workshop tips and smart repairs ; long and successful runs; interesting photographs : all are suitable subjects. Send a post-card, or a letter, or a sketch to us—no matter how short, or how written, or how worded. We will " knock it into shape" and prepare sketches, where necessary, before publication. The absence of a sketch dies not disqualify for a prize. When se.riting use one wide of the paper only and mention your employer's name as a guarantee of bona fides. Neither your own nor your employer's name will be disclosed. Payment will be made immediately after publication. Address your letters to The Editor, THE COMvIE&CLtL MOTOR, 7-15. le osebery Avenue. London. E .C.
Drivers are reminded that entries for the Commercial-Vehicle Parade should be made before the 5th of May. The prize list now amounts to over £200. Copies of the Parade Rules can be obtained from the Secretary of the C.M.U.A., 89, Pall Mall, S.W.
Piston Rings Made from a Stack Pipe.
[861 " MECHANIC" (Peckham) writes Some
time ago we had a great rush for piston rings. We simply had to get hold of some somehow, and I therefore had to scheme a method which would he quick and good at the same time. I had a good hunt round for material, but the only thing that I could find was a piece of L.C.C. cast-iron stack-pipe. This happened to be of the right size, and remarkable to relate I was able to make some splendid piston rings from it. It would not have been supposed that the material used for such a job as that would have been good enough for piston rings, but it must suffice for me to tell you that those which I produced have been running for well over a year. " The ordinary method of turning, splitting and then re-turning was rejected, on the occasion to which I refer, as being elaborate and taking up too much time. I therefore adopted the following arrange ment. First of all the tube was held in the chuck somewhat out of centre, and the inside was bored slightly larger ; then the tube was again chucked in order that the outside might be turned. For the last operation, of course, the material was properly centred. The turning was down to a dimension which made a moderately-tight fit in the cylinder, and then with a parting tool the rings were cut off. A very-keen tool and considerable care were required for this part of the operation. Where the parting had been made the surface was rubbed smooth on a sheet. of emery cloth stretched on a flat board. The rings were then split with a hacksaw, two in one direction and one in the opposite direction. In order to get the necessary spring, the rings were hammered with a small ball-pane hammer on the inside at the thick part of the section up to about a third of the way round. The expansion of the rings, owing to the heat of the engine was sufficient aloiost to close the slots."
Gauging the Gudgeon.
The sender of the following communication has been awarded the 10s. prize this week.
[868] " F.C.F." (Slough) writes :—" I send you a rough sketch [We have had this redrawn.—En. II and a. description of an adjustable straight edge, which I have designed for use in connection with the squaring up of connecting rods after they have been fitted.
"Most of your readers w,ill be aware that, although the utmost care may be observed during the operation of boring the bearings, and although the greatest skill may be applied to the subsequent scraping of them, more often than not it will be found that the axis of the repaired bearing, when it is put into position, is not exactly in line with that of the gudgeon pin ; the centre line of the gudgeonpin bush will frequently be found to be inclined to the centre line of the crankshaft, owing to the fact that the rod has become twisted to a slight extent. It is not easy always to detect this defect before erection, and it was to avoid the necessity of waiting until the cylinders were put into place and until the engine was tried over, that I contrived a special straight edge, about which I am writing to you. If this be used in conjunction with a length gauge, one end of which has a V block on it, whilst the other end has a screw extension piece on it, the slightest devia tion from truth in the horizontal plane may readily be detected. Similar discrepancy in the vertical plane may be discovered by the use of my special straight edge in conjunction with an ordinary straight edge laid along the crank cheeks. My sketch renders any elaborate explanation of the contrivance unnecessary, but it will be noticed that I have arranged for adjustment in order to accommodate worn gudgeon bushes or those of larger or smaller dimensions than standard ; two setscrews provide for this ; other setscrews in the side of the straight edge provide for the taking up of any slack sidewayr."