This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1876 Excerpt: ...time a very complicated one, which could be simplified with advantage. This may be done for instance by giving up the automatic feed movement during the boring. It is impossible to do without men to look after the working of the machines, and these men may just as well feed the drilling part forwards along a screw, by ...
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This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1876 Excerpt: ...time a very complicated one, which could be simplified with advantage. This may be done for instance by giving up the automatic feed movement during the boring. It is impossible to do without men to look after the working of the machines, and these men may just as well feed the drilling part forwards along a screw, by means of a handle, sufficiently to let the piston always have its full stroke, without striking against the ends of the cylinder. This simplification, analogous to that of which we are have spoken in connection with coal-cutting machines (No. 157), would be particularly useful in an ordinary mine level, where the machines may easily be looked after, because they are necessarily few in number. (164) Numerous perforators have been tried during the last twenty years. We may mention Schwarzkopi'f s machine, in which compressed air acting on a piston drove a sort of hammer against the borer. We have already seen that this system is inferior to the plan of making compressed air act directly on the tool itself. We may also cite Schumann's machine, which was not sufficiently automatic; then the machines of Doering, Bergstrcem, Sachs, Haupt, Crease, Burleigh, etc., etc., in most of which ingenious mechanical movements may be observed. However, it seems to us that too much trouble has been taken, cither to reduce the weight ot the machine so as to facilitate the handling (some machines have been made weighing less than lewt.), or to make it too completely automatic, for this cannot be done without complicating the parts. A very light and at the same time complicated machine is necessarily weak, and requires frequent repairs. We think it is better to make a perforator simple and strong, even if these requirements should cause it to be less easily set up ...
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