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2020-09-20 04:16:21


The gearing of these machines is alluded to here mainly for the purpose of calling attention to what constitutes a new and singular mechanical movement, one that will furnish a most interesting study, and deserves a more extended application in producing slow reciprocating motion.

The fitting or finishing department of engineering establishments is generally regarded as the main one.

As a means for transmitting power, shafts afford the very important advantage that power can be easily taken off at any point throughout their length, by means of pulleys or gearing, also in forming a positive connection between the motive-power and machines, or between the different parts of machines. The capacity of shafts in resisting torsional strain is as [46] the cube of their diameter, and the amount of torsional deflection in shafts is as their length. The torsional capacity being based upon the diameter, often leads to the construction of what may be termed diminishing shafts, lines in which the diameter of the several sections are diminished as the distance from the driving power increases, and as the duty to be performed becomes less. This plan of arranging line shafting has been and is yet quite common, but certainly was never arrived at by careful observation. Almost every plan of construction has both advantages and disadvantages, and the best means of determining the excess of either, in any case, is to first arrive at all the conditions as near as possible, then form a "trial balance," putting the advantages on one side and the disadvantages on the other, and footing up the sums for comparison. Dealing with this matter of shafts of uniform diameter and shafts of varying diameter in this way, there may be found in favour of the latter plan a little saving of material and a slight reduction of friction as advantages. The saving of material relates only to first cost, because the expense of fitting is greater in constructing shafts when the diameters of the different pieces vary; the friction, considering that the same velocity throughout must be assumed, is scarcely worth estimating.

In passing thus rapidly over so important a subject, and one that admits of so extended a consideration as machinery of transmission, the reader can see that the purpose has been to touch only upon such points as will lead to thought and investigation, and especially to meet such queries as are most likely to [57] arise in the mind of a learner. In arranging and erecting machinery of transmission, obviously the first problem must be, what kind of machinery should be employed, and what are the conditions which should determine the selection and arrangement? What has been written has, so far as possible, been directed to suggesting proper means of solving these questions.For implements procure two drawing-boards, forty-two inches long and thirty inches wide, to receive double elephant paper; have the boards plain without cleets, or ingenious devices for fastening the paper; they should be made from thoroughly seasoned lumber, at least one and one-fourth inches thick; if thinner they will not be heavy enough to resist the thrust of the T squares.

In no other branch of machinery has so much research and experiment been made during eighty years past as in steam machinery, and, strange to say, the greater part of this research has been directed to the details of engines; yet there has been no improvement made during the time which has effected any considerable saving of heat or expense. The steam-engines of fifty years ago, considered as steam-using machines, utilised nearly the same proportion of the energy or power developed by the boiler as the most improved engines of modern construction—a fact that in itself indicates that an engine is not the vital part of steam machinery. There is not the least doubt that if the efforts to improve steam-engines had been mainly directed to economising heat and increasing the evaporative power of boilers, much more would have been accomplished with the same amount of research. This remark, however, does not apply to the present day, when the principles of steam-power are so well understood, and when heat is recognised as the proper element to deal with in attempts to diminish the expense of power. There is, of course, various degrees of economy in steam-using as well as in steam-generating machinery; but so long as the best steam machinery does not utilise but one-tenth or one-fifteenth part of the heat represented in the fuel burned, there need be no question as to the point where improvements in such machinery should be mainly directed.

An interesting example in the use of belts for communicating power to movable machinery is furnished by the travelling cranes of Mr Ramsbottom, in the shops of the L. & N. W. Railway, at Crewe, England, where powerful travelling cranes receive both the lifting and traversing power by means of a cotton rope not more than three-fourths of an inch in diameter, which moves at a high velocity, the motion being reduced by means of tangent wheels and gearing to attain the force required in lifting heavy loads. Observing the operation of this machinery, a person not familiar with the relations between force and motion will be astonished at the effect produced by the small rope which communicates power to the machinery.

This principle is somewhat obscure, and the nature of percussive forces not generally considered—a matter which may be illustrated by considering the action of a simple hand-hammer. Few [103] people, in witnessing the use of a hammer, or in using one themselves, ever think of it as an engine giving out tons of force, concentrating and applying power by functions which, if performed by other mechanism, would involve trains of gearing, levers, or screws; and that such mechanism, if employed instead of a hammer, must lack that important function of applying force in any direction as the will and hands may direct. A simple hand-hammer is in the abstract one of the most intricate of mechanical agents—that is, its action is more difficult to analyse than that of many complex machines involving trains of mechanism; yet our familiarity with hammers causes this fact to be overlooked, and the hammer has even been denied a place among those mechanical contrivances to which there has been applied the name of "mechanical powers."

1. The most economical and effectual mechanism for handling is that which places the amount of force and rate of movement continually under the control of an operator.

It is important, in asking questions, to consider the mood and present occupation of the person addressed; one question asked when a man's mind is not too much occupied, and when he is in a communicative humour, is worth a dozen questions asked when he is engaged, and not disposed to talk.

Institute of Plasma Physics, Hefei Institutes of Physical Science (ASIPP, HFIPS) undertakes the procurement package of superconducting conductors, correction coil, superconducting feeder, power supply and diagnosis, accounting for nearly 80% of China's ITER procurement package.

"I am so proud of our team and it’s a great pleasure for me working here," said BAO Liman, an engineer from ASIPP, HFIPS, who was invited to sit near Chinese National flay on the podium at the kick-off ceremony to represent Chinese team. BAO, with some 30 ASIPP engineers, has been working in ITER Tokamak department for more than ten years. Due to the suspended international traveling by COVID-19, most of the Chinese people who are engaged in ITER construction celebrated this important moment at home through live broadcasting.

One of ASIPP’s undertakes, the number 6 poloidal field superconducting coil (or PF6 coil) , the heaviest superconducting coil in the world, was completed last year, and arrived at ITER site this June. PF6 timely manufacturing and delivery made a solid foundation for ITER sub-assembly, it will be installed at the bottom of the ITER cryostat.

Last year, a China-France Consortium in which ASIPP takes a part has won the bid of the first ITER Tokamak Assembly task, TAC-1, a core and important part of the ITER Tokamak assembly.

Exactly as Bernard BIGOT, Director-General of ITER Organization, commented at a press conference after the ceremony, Chinese team was highly regarded for what they have done to ITER project with excellent completion of procurement package.


The kick-off ceremony for ITER assembly (Image by Pierre Genevier-Tarel-ITER Organization) 


the number 6 poloidal field superconducting coil (Image by ASIPP, HFIPS) 


ITER-TAC1 Contract Signing Ceremony (Image by ASIPP, HFIPS)

World dignitaries celebrate a collaborative achievement

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