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25th July 1918, Page 21
25th July 1918
Page 21
Page 21, 25th July 1918 — For DRIVERS, MECHANICS & FOREMEN.
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Which of the following most accurately describes the problem?

A PRIZE OF TEN SHILLINGS is awarded each week to the sender of the best letter which we publish on this page ; all others are paid for at the rate of a penny a line, with an allowance for photographs. All notes are edited before being published. Mention your employer's name, in confidence, as evidence of good faith. Address, D., M. and F., " The Commercial Motor," 7-15, Rosebery Avenue, London, E.C. I.

Lamps Alight.

On Saturday, the 27th July, light your lamps at 9.25 in London, 10.27 in Edinburgh, 9.46 in Newcastle, 9.44 in Liverixml, 9.36 in Birmingham, 9.45 in Bristol, and 10.28 in Dublin. °

Repair to a Broken Cylinder.

The sender of the following communication has been awarded the 10s. prize this week.

[1882] " A.H." (Greenock) writes :—" I had an awkward repair job to carry out recently, a description of which will, no doubt, interest other readers of your 'P., M. and F.' page. The four-cylinder engine on my lorry embodies two twin-cylinder blocks, and on each of these a projecting boss, as shown in the "sketch [which we have had redrawn.—En.], serves to accommodate One of the studs-for securing the exhaust and induction manifolds. I had the misfortune to break one of these lugs off, the fracture extending right through the stud hole. The stud came away, and there was nothing with which to keep the pipes in place. An immediate repair was,..theref ore, Imperative.

A round of the various welding and repair shops in the district failed to discover anyone who would tackle the job and weld a new piece of boss on. The objection in all cases was that any such procedure would, in all probability, result in cracking the water jacket, so that our last state would be worse than the first. As time would not permit of the casting being despatched to more important centres where, no doubt, larger and more responsible firms, with wider experience, would have been able to carry out the work, it became incumbent upon me to effect a repair as best I could in the circumstances.

"I commenced operations by chipping and filing that portion of the boss which still adhered tothe cylinder casting until its edge was perfectly smooth and flat. It happened so to have broken that when this operation was completed, there vfias still half of the circumference of the stud hole left intact. I then procured two pieces of mild steel plate, each of which was large enough to complete the boss and bring it back to its original dimensions. These were trued up and a semi-circular groove filed in each of such a size that, when clamped together with • groove facing groove, the hole thus formed could eventually be tapped the same size as the stud in the cylinder.

"Alternatively, of course, I could have taken one solid piece of steel twice the size, drilled it, tapped it, and sawn it in two down the centre of the tapped hole. In the circumstances the method described appealed to me as being the easier of accomplishment. One of these pieces of metal was, of course, discarded as soon as the hole was drilled and tapped. The other one I drilled and countersunk, as shown in the sketch, for a. couple of screws. I pressed the stud in place in the half of the boss which was still attached to the cylinder, and placed the piece of steel in place over the stud f then marked off, drilled and tapped a couple of heles to receive the counter sunk screws in this new portion of boss, taking care not to penetrate the water jacket. With these screws in place and tightened up, a satisfactory foundation was made for the holding-down stud, and the repair (which has now been completed for some time) has proved quite successful. "I may say that I adopted this somewhat unusual method of drilling the hole in the new half of the boss as being preferable to the more obvious one of securing the piece of boss in place, and afterwards drilling both casting and boss, for the reason that by the latter method I should have been troubled by the natural tendency to take more out of the softer metal—cast iron—which would have been objectionable for two reasons. In the first place, there was little enough metal left between stud hole and cylinder jacket ; secondly, I should not, under these conditions, have been able-to replace the stud in its correct position relative to the others.

"I also enclose a sketch [which we have had: redrawn.—ED.] of a valve spring lifter, which I suggest is an improvement upon the one described recently in yourM. and F.' page by ' S.R.H.,' letter 1818. I think it is easier to make, and it has also the advantage that when in use it performs the double function of holding the valve firmly in its place and lifting the spring."


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