Contributions from Drivers and Mechanics.
Page 22
Page 23
If you've noticed an error in this article please click here to report it so we can fix it.
TEN SHILLINGS WEEKLY for the Best Communication Received, and One Penny a Line of ten words for any.
thing else published.
Drivers of co.nntercial-motor vehicaes and tractors, and mechanics and foremen of garages or shops, are invited to send short contrinutions on any subject which is likely to prove of interest to our readers. Work. shop 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 11.41., 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. 1Vhen writing use one side of the paper only and men 'ion your employer's name as a guarant,e 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, Nosebery Avenue, London, E.C.
Yearly Bonuses for Contributors.
In order further to encourage regular contributors to these pages, we have recently decided to offer two additional prizes, as follow : A bonus of two guineas to the contributer who succeeds in securing the weekly ten-shilling prize for the largest number of times during the twelve months ending let December, 1910.
A bonus of one guinea to the contributor who has the largest number of individual contributions inserted during the twelve months ending 1st December, 1910.
Backing Off Flat Valve Seats.
The sender of the following contraunirotion has been awarded the Ws. prize this icei.le
[660] " H.W." (Slough) submits a description of a useful tool which he and another man contrived, in order to bore round the outsides of flat valve seats. which had worn down below the surrounding casting.—" On the engine of an old — type of motorbus chassis, some of the valve seats, which were of the flat pattern, had gradually worn and been ground down so far that the valves were actually seating in a pocket below the level of the wall casting. The effect of this wear was, of course, that the lift from the cams was no longer enough to allow sufficient passage for the gases past the valves when they were actually supposed to be fully open. The engine in question had, before we discovered this trouble, recently been overhauled and reassembled, hut the man who did the job had not noticed the worn seats; he had been content to grind in the valves again. We located the fault when the engine was on the test bench. We could get no power out of two of the cylinders, but subsequent examination revealed the fact that their seats were worn right down into pockets. The engine in question was wanted at once, and, as we bad no spare cylinders in stock. we set to work to make a special boring tool to enable
us to back off the metal all round the flat seats. The principal trouble we encountered was rather a puzzling one. The coned seats of the valve covers were practically of the same diameter as the head of the valve, and, of course, in order to cut round the outside of the seats, the tool would have to stick out beyond this diameter, We finally got over this difficulty quite easily by making the toolholder of the eccentric shape shown in my sketch. We have had this redrawn.—ED.] The bottom stem of the tool had to be just short enough to allow the disc, which acted as a tool-holder, to drop clear into the valve pocket before entry was made into the valve-spindle guide. The tool could thus be passed down the valve cover aperture eccentrically, and then he moved sideways in order to be centred properly. The under face of the eccentric disc acted as a stop for the cut; the tool was held and adjusted respectively by two small set-screws. This contrivance enabled us to put the seatings right, without the need of dismantling the cylinders. We did the first job quite satisfactorily, and the tool has, without any modifications, often been in use since."
File Your "D. and M." Pages.
.061] " TIMON " (Paisley) writes :—" I should like to tell you of the way in which I can point to my practical appreciation of your weekly Drivers' and Mechanics" pages of tips. For some years past I have had a copy of the Motor Manual ' This is produced under the auspices of our sister journal 'The Motor.'--.ED.] and have kept it by me for general reference, but, for special hints and tips a ith regard to the repairs, maintenance and running of industrial vehicles, I find the D. and M.' pages of the ` C.M.' invaluable. The method I adopt to preserve these in handy form is, each week, to tear out these pages from the issue, as carefully as possible, and to keep them in a cardboard file which a pal of mine, who is a stationer, gave me. it has got printed on it The Stolzenburg File ' ; I don't know whether you have seen one. I've got nearly 150 pages filed like this now. All I want to make my collection really useful is an index. Couldn't you publish a short one for this purpose? Will you send me copies of the issues dated 6th May, 1909, and 3rd December. 1908? I want these to make my file oomplete. enclose stamns."
fOur correspondent's method is quite a useful one, although it involves the destruction of his weekly copy. The " Stolzenburg " files are quite well known to us. They are about Sd. each and can be obtained at most staiioners in suitable sizes. There are other makes whieh are quite as good for the purpose. " Timon " might do worse than write to the Manager, THE COMMERCIAL MOTOR, Ilasebery Avenue, for a copy of the index to the complete volume. He could cut out that part which refers to the " Drivers' and Mechanics' " contributions and paste it on the inside of the file cover. We have &spat-lied the two copies which are requested.—En.]
Making a Starting-handle Clutch. More About Accumulators.
[662] " N.C." (Batley) writes as follows:—' J. oiler you a few lines with regard to the making of the ordinary form of jaw clutch which is commonly used in conjunction with starting-handles. Although this is something which is not often wanted, when it is, it is generally wanted nadly ; the following particulars may be of interest. "On examining the teeth of a clutch you will notice that they form part of a worm ; they must be of this shape in order to engage and to release readily. The method which I have used to cut such teeth—and it makes a firstclass job of them—has been as fdlows. The depth of the teeth of the clutch had to be + in., and each tooth had to start .at nothing and to rise * in. in half a turn. This is
equal to in. in one full turn.
"Having ascertained the pitch, the blanks had lines scribed parallel to the axis, at opposite points on the diameter. A. slight centre-punch dot is then made, at from one end—to show the depth of the tooth. Then a 3-16 in. hole is drilled in the corner, and the blanks are ready for cutting.
" They must then be driven on to a mandrel and this must be placed in a lathe. The change-wheels must. be set SO as to cut a in.-pitch screw, i.e., two threads to the inch. The back-gear must be put in, and a short stiff parting tool should be fixed in the rest. Next pull the belt round a turn, so as to take out the backlash. Then set the tool up into such a position that it will first start to cut at the tip of one tooth. Give the tool a. slight feed and pull the belt round until the tool cuts part of a screw thread into the small hole which has already been drilled. Continue in the same way until you have cut right through into the bore of the blank. With a nice tool you will be surprised how soon this may be done. " I. should like, on this occasion, to make a few remarks re part of my last contribution on accumulators. [Letter No. 622, published 2nd December, 1909.—ED.] The last paragraph should have read 'form the plate in a strong solution of chloride of lime for a quarter of an hour.' As it was printed, it read as if the given time was for washing the plate, instead of for forming it. You inserted a note saying, Resin should not be necessary with new metal.' I think you forgot that the lugs, after being used and after standing in the acid, cannot be considered to be new.
"In reply JAY GEE,' Letter No. 638, I am quite aware that celluloid cement can be bought, but it takes no time to make, and you can make as much for sixpence as two shillings would buy in a shop. I would sooner use my own stuff. Perhaps it is only fancy, but I think it dries quicker and holds better. A good repair can certainly be made with Chatterton Compound, but what about the appearance of the job P The forming of the plates in chloride of lime, although it may be quite new to JAY GEE,' is a perfectly-correct method. It is almost as good as alternate recharging, and is, certainly, far in advance of replacing the plate without forming. I might say it is only necessary to form the positive plates. I should not advise anyone to replace positives without forming, because I don't think the paste would hold together. I could go much further into the matter, as I have studied and taken a, great interest in accumulators, from the early times when all motor-vehicles were 'boxes of mystery.' If JAY Gen ' is doubtful upon any other point or would like to argue, I shall be happy to oblige him." [Our correspondent's ingenuity is of interest. The need for such accuracy is, however, not apparent. In some cases the starting clutch engages with the starting pin in the crankshaft not more than three times a day .—ED.]