Contributions from Drivers and Mechanics.
Page 19
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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 vehicles and tractors, and mechanics and foremen of garages or shops, are invited to send short contriOutions on any subject which is likely to prove of interest to our readers. Workshop tips and smart repairs ; long and successful runs ; interesting photographs : all ore 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 does not disqualify for a prize. When writing use one side 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 COMMERCIAL MOTOR, 7-15, Rosebery Avenue, London, E.C.
'Something for Nothing."
With reference to his contribution, describing a method of charging aectenulators off the mains, which was published in our last issue, as letter No. 771, on page 85,
" (Beckenham) writes.—" When referring to 12 lamps on a. circuit, I presumed that. all consemers will shortly be using the metal filament type of incandescent lamp, as the carbon pattern is rapidly passing out of use. My suggestion that ceiling roses should be used, was in order to enable a fuse to he inserted, so as to prevent overcharge ot the battery_ The two-way switch enables eidirmry circuit switches to be used as desireu."
An Adjustable Crosshead Bush.
7721 " A.P." (Monmouth) writes.—" I have been a reader of your valuable journal since it was shown to me a friend some 15 months ago. As I have, on many oecasions, been glad of your tips, I think I should like to give your readers one in return. I drive a steam wagon, and, up till quite recently, I had been having quite a lot of trouble with the crossheads ; the defect in question was indicated by a very bad knock. The crosshead bush was of white metal, and, of course, when this metal wore, the gudgeon pin would soon become slack. There was no means of tightening up the existing bush, so I proceeded to make a new one. This I made of gunmetal, and I cut a slit right through one side of it. I drilled the crosshead and tapped it to make a suitable set-screw, which could be screwed up against the bush, so as to close it in slightly when required. A lock-nut on the set-screw kept the adjustment in position.'
Some Hints About White-metalling.
77:I! (Slough) writes.---" I submit, for your consideration, a few tips with regard to the metalling and hitting of big-ends. A very-good plan, when big-end shells are being machined, is to run a. coarse thread through them, with the tool held well out in the rest, so as to leave a jagged cut ; this assists the white metal to get a satisf;,ctory hold.
" It is, of course, usual to employ some form of mandrel NS hen pouring. the molten antifriction metal into the shells, and it is, as a rule. difficult to keep these tight, as they or their stands are frequently made in halves. All likely places where leakage could take place should be stopped with clay. Another method is to enclose the whole metalling arrangement in a piece of large-diameter steel tube, filled up with sand.
" Before pouring, the metal should be heated to such a pitch that a piece of white-pine wood, just dipped and ithdrawn, should have turned brown. Pieces of this wood should be kept handy, as they are very useful to poke about and stir the metal with. The big-end, in ,position on the mandrel, should, previous to pouring, be warmed ,SO that it cannot be touched—just so warm, in
filet, that if a spot of water be dropped on, it will sizzle. After the metal is poured, it should be kept stirred and agitated as much as convenient, in order to expel any gas that may he present.
" When machining, in order to ensure truth and squareness, the bearings should be held in a jig on a lathe saddle, and a small rotating bar with adjustable cutters should be used to bore it out, and to round off the edges. It is always advisable to take as little out of the bearing as possible, so that the harder outer skin may remain. Therefore, when a pair of bearings is required for a 46-mm. crankpin, it is advisable to take a pair which have been metalled on a 4,5-mm. mandrel. I hope to submit to you seine further notes about a special form of mandrel that I hare used with seceess for white-metalling."
Pushing a Dented Pipe into Shape.
The sender of the following communicativn has been awarded the 10s. prize this week.
1.774.1 " Tony " (Cardiff) writes.—" I offer the following tip 'for your D. and M.' page, in the hope that it may be found interesting.
" Some few weeks ago, I had to get a bad dent out of
in. copper pipe, and, as the pipe was bent at both ends, it appeared to be almost an impossible job without cutting the pipe. However, f set about it in the following manner. I turned a steel ball slightly smaller than the internal diameter of the tube. I next drilled a 3-16th-in. hole through the centre and broached this out to diameter to a depth of 1 in. I then obtained a piece of flexible steel wire about 1, in. thick and made a knot on one end. 1 passed this through the steel ball until the knot was inside. A little oil was run into the tube, and the ball was then pulled through by the aid of a hammer shaft with the wire wound around it. The result was very satisfactory. I should state, in conclusion, that I first annealed the pipe where it was dented."