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    Software name: appdown
    Software type: Microsoft Framwork

    size: 584MB

    Lanuage:Englist

    Software instructions

      Chasing operations being lathe work, and involving no principles not already noticed, what is said further will be in reference to die-cutting or bolt-threading machines, which, simple as they may appear to the unskilled, involve, nevertheless [144] many intricacies which will not appear upon superficial examination.


      Attention has been called to this case as one wherein the conditions of operation obviously furnish true data to govern the arrangement of machinery, instead of the determinable strains to which the parts are subjected, and as a good example of the importance of studying mechanical conditions from a practical and experimental point of view. If the general diameter of a shaft is based upon the exact amount of power to be transmitted, or if the diameter of a shaft at various parts is based upon the torsional stress that would be sustained at these points, such a shaft would not only fail to meet the conditions of practical use, but would cost more by attempting such an adaptation. The regular working strain to which shafts are subjected is inversely as the speed at which they run. This becomes a strong reason in favour of arranging shafts to run at a maximum speed, provided there was nothing more than first cost to consider; but there are other and more important conditions to be taken into account, principal among which are the required rate of movement where power is taken off to machines, and the endurance of bearings.I could not get much information from them. Twenty spoke at the same time; in halting, incoherent words they tried to tell me of their experiences, but I could only catch: killed ... murders ... fire ... guns.... After much trouble I gathered that they came from the villages to the north of Lige, where the Germans had told them35 that on that same day, within an hour, everything would be burned down. Everybody had left these places, a good many had gone to Lige, but these people did not think it safe there either, and wanted to go on to The Netherlands.


      After driving through this scene of misery we158 entered Charleroi, and exactly at that moment one of the springs of my motor broke in two, which made the car useless. Charleroi seemed worse damaged than Namur. According to an official statement issued at the time, one hundred and sixty-five houses had been burned, among them many on the fine Boulevard Audent, the Saint Joseph Institute, the convent of the S?urs de Namur, and the adjacent ancient, miraculous little chapel of "Sainte Marie des Remparts."The intricacy of the subject renders it a difficult one to deal with except by the aid of diagrams, and as such mechanism may be inspected in almost any machine fitting shop, attention is called to the subject as one of the best that can be chosen for demonstration by diagrams. Problems of these variable speed movements are not only of great interest, but have a practical importance not found in many better known problems which take up time uselessly and have no application in a practical way.

      To learn to chip and file is indispensable, if for no other purpose, to be able to judge of the proficiency of others or to instruct them. Chipping and filing are purely matters of hand skill, tedious to learn, but when once acquired, are never forgotten. The use of a file is an interesting problem to study, and one of no little intricacy; in filing across a surface one inch wide, with a file twelve inches long, the pressure required at each end to guide it level may change at each stroke from nothing to twenty pounds or more; the nice sense of feeling which determines this is a matter of habit acquired by long practice. It is a wonder indeed that true surfaces can be made with a file, or even that a file can be used at all, except for rough work.

      (1.) Why are machine frames constructed in sections, instead of being in one piece?(2.) Why must parts which have contact on opposite sides have specific dimensions?(3.) What are standards of measure based upon in England, America, and France?(4.) How can weight be measured by time?(5.) Has the French metre proved a standard admitting of test reference?To sum upWe have the following propositions in regard to moving and handling material:


      "All right, sir."

      Milling tools large enough to admit of detachable cutters being employed, are not so expensive to maintain as solid tools. Edge movement can sometimes be multiplied in this way, so as to greatly exceed what a single tool will perform.The art of keeping reasonably clean even in a machine shop is worth studying; some men are greased from head to foot in a few hours, no matter what their work may be; while others will perform almost any kind of work, and keep clean without sacrificing convenience in the least. This difference is the result of habits readily acquired and easily retained.

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      This difference between dead and elastic strokes is so important that it has served to keep hand-moved valves in use in many cases where much could be gained by employing automatic acting hammers.CHAPTER XXII. PATTERN-MAKING AND CASTING.

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      A second point to be noticed in hammers of this class is the nature of the connection with the driving power. In all cases there will be found an equivalent for the elastic helve of the trip-hammereither air cylinders, deflecting springs, or other yielding attachments,interposed between the crank and the hammer-head, also a slipping frictional belt or frictional clutches for driving, as in the case of trip-hammers.Before I got there I passed the Halls of Louvain, the building that contained the world-famous library, with its numerous art-treasures. Only the outer walls were left standing, inside it was all ruins. All was reduced to dust, to miserable rubbish, and never will one single page be recovered of all those thousands of burned manuscripts.


      alllittle