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Mechanics magazine
- Bandzählung
- N.S. 23=92.1870
- Erscheinungsdatum
- 1870
- Sprache
- Englisch
- Signatur
- A146
- Vorlage
- Universitätsbibliothek Chemnitz
- Digitalisat
- Universitätsbibliothek Chemnitz
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- SLUB Dresden
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- urn:nbn:de:bsz:14-db-id507363582-187000013
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- http://digital.slub-dresden.de/id507363582-18700001
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- oai:de:slub-dresden:db:id-507363582-18700001
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- Projekt: Bestände der Universitätsbibliothek Chemnitz
- LDP: Bestände der Universitätsbibliothek Chemnitz
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Zeitschrift
Mechanics magazine
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Band
Band N.S. 23=92.1870
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- Titelblatt Titelblatt -
- Register Index to vol. XXIII I
- Register Illustrations to vol. XXIII IV
- Ausgabe Jan. 1, 1870 1
- Ausgabe Jan. 8, 1870 19
- Ausgabe Jan. 14, 1870 37
- Ausgabe Jan. 21, 1870 55
- Ausgabe Jan. 28, 1870 73
- Ausgabe Feb. 4, 1870 91
- Ausgabe Feb. 11, 1870 109
- Ausgabe Feb. 18, 1870 127
- Ausgabe Feb. 25, 1870 145
- Ausgabe Mar. 4, 1870 163
- Ausgabe Mar. 11, 1870 181
- Ausgabe Mar. 18, 1870 199
- Ausgabe Mar. 25, 1870 217
- Ausgabe Apr. 1, 1870 235
- Ausgabe Apr. 8, 1870 253
- Ausgabe Apr. 15, 1870 271
- Ausgabe Apr. 22, 1870 289
- Ausgabe Apr. 29, 1870 307
- Ausgabe May 6, 1870 325
- Ausgabe May 13, 1870 343
- Ausgabe May 20, 1870 361
- Ausgabe May 27, 1870 379
- Ausgabe June 3, 1870 397
- Ausgabe June 10, 1870 415
- Ausgabe June 17, 1870 433
- Ausgabe June 24, 1870 451
- Ausgabe No. 2361 I
- Ausgabe No. 2362 I
- Ausgabe No. 2363 I
- Ausgabe No. 2364 I
- Ausgabe No. 2365 I
- Ausgabe No. 2366 I
- Ausgabe No. 2367 I
- Ausgabe No. 2368 I
- Ausgabe No. 2369 I
- Ausgabe No. 2370 I
- Ausgabe No. 2371 I
- Ausgabe No. 2372 I
- Ausgabe No. 2373 I
- Ausgabe No. 2374 I
- Ausgabe No. 2375 I
- Ausgabe No. 2376 I
- Ausgabe No. 2377 I
- Ausgabe No. 2378 I
- Ausgabe No. 2379 I
- Ausgabe No. 2380 I
- Ausgabe No. 2381 I
- Ausgabe No. 2382 I
- Ausgabe No. 2383 I
- Ausgabe No. 2384 I
- Ausgabe No. 2385 I
- Ausgabe No. 2386 I
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Band N.S. 23=92.1870
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THE MECHANICS’ MAGAZINE. LONDON: FRIDAY., FEBRUARY i, 1870. CLIP DRUMS. O F tlie various items comprised in the list of engineering triumphs, that known as steam ploughing is not least in value and im portance, and as each greater work is usually composed of an aggregate of smaller ones, the steam plough in its present state of per fection is but a collection of devices each contrived to overcome some special difficulty encountered by those who have laboured to render steam available as a tiller of the soil. Perhaps of all the improvements effected in this direction none has proved at once more valuable and more effective than the expedient invented for supplying sufficient hauling power on the rope without inter fering with its arrangement as an endless belt. There are a variety of places where it would be a matter of convenience to transmit power through a space too great for the ordinary “lay shaft” to be applicable, the only alternative being the endless belt. Up to the present we can count on but three materials for belts, whatever their dimen sions ; these are leather, india-rubber com bined with canvass, and the wire rope. AVe do not mention hemp, as it is so perishable as to be virtually out of the category. For considerable lengths, say such as two or three hundred feet, leather belts become so costly as frequently to render the arrange ment of a separate soui co of power in each place preferable to its use as a mode of transmission. Of late years, we might almost say months, attention has been more generally directed to the use of wire ropes as belting for con siderable spans, and there is little doubt that, were some inexpensive means invented which would secure the necessary eo-efficient of fric tion between the rope and the pulleys running it, the adoption of this mode of transmitting power over spans exceeding 25ft. or 30ft., if not indeed for much shorter ones, would become very general; but though the need of some such plan is felt, but little attention appears to have been turned to the subject, so little indeed that the long span through which power was transmitted by a wire rope in the grounds of the last French Exhibition Palace at Paris, was considered in some sort as a species of novelty. However admirably the clip drum may perform its work with steam ploughing tackle, it is far too costly for general work in other ways, save in cases of comparative magnitude. AVe are satisfied that were the need for a good general purpose clip drum so great as to amount to a necessity, more than one good one would be invented; but, in spite of all our go-aheadness, wo have still a considerable germ of conservatism, and this individual want is too much divided amongst various small inconveniences to stimulate invention on the subject. AVhen it is proposed to transmit power through an endless rope of wire the questions of adhesion are in most of their aspects identical with locomotive adhesion, one half directly, the other half inversely, the driving pulley being directly identical with the driving wheel of the locomotive, and the driven pulley being inversely so. It is obvious that in either case the object is simply to secure a coefficient of friction between the surface giving and that receiving the power, which shall exceed, however slightly, the force tending to cause the belt to slip. The rope being practically a level surface, no expedient partaking of the nature of toothed gear is at all practicable. Nothing remains therefore but to increase the friction. This can be done only by either of two ways— first, to draw the belt so tight as to cause it to bite sufficiently ; the second is to provide a means to pinch the rope. The latter we have in the clip drum or the V groove. The principle of the former is almost perfect, but its ap plication very costly. Almost the only defect of the clip is its tendency to pinch the rope out of shape under excessive strain, as well as to prevent its rotation on its own axis, and this is a point worth some consideration, as any rope running over porter pulleys has. a constant rotary motion on its own axis proportionate to its pitch of twist. The remedy appears difficult, but the evil is fortu nately not great. In scheming any pulley to transmit power to or from a wire rope, the amount of power must be carefully considered if the durability of the rope is of any importance. A rope is very different to a leather belt, as, the rubbing area of the latter being proportionate t"> its width, it can be readily adapted to its work by regulating that,while the sectional strength of the rope increases so much more quickly than its rubbing area that something of the “ pinch ” principle is almost a necessity of its use as a belt. Accepting the evil as inevitable, the next best course is to reduce it to the least possible magnitude ; therefore, the amount of power to be transmitted should be ascertained as nearly as possible, and the drums or pulleys constructed to furnish just enough “ pinch ” and no more. This na turally leads us to consider the groove in the rim of the pulley, as its sectional form must be the basis of the question. Data have been collected by experiments and practice, from which we have formulae to compute the power a belt of leather of a given breadth will transmit, but no such data is to hand as regards wire belts, though there i3 no reason why we should not possess one. There is little doubt that nearly all the power at pre sent transmitted by leather could equally well be conveyed by wire and at a great reduction of cost. The fact of having to shift belts to reverse or shut off power need present no obstacle to its introduction, as more than one means can be devised to provide for this question. A few experiments, in which the circumference of rope, the angle of the V of groove in a plain drum, or of the clips in a clip drum, the statical strain, or that merely of the tension common to both sides of the belt, and the amount of tension on one side in excess of the other before the belt slipped, with various shapes of section of groove, would speedily furnish us with much valuable information on so important a subject as the transmission of power through some cheaper material than leather, or one less clumsy than a chain. THE FAIRLIE ENGINE. IIE special construction of locomotive engine known as the Fairlie system, and which consists of a double engine carried on two bogie frames, is at length receiving from our railway authorities and the public the attention it merits. The untiring energy displayed by Mr. Fairlie in developing the system is now, we are glad to say, bringing forth fruits. Railway men are beginning to recognise the truth of the principles it embodies and are giving it a fair practical trial. It is only about six months since we descr ibed the construction and working of a steam carriage on Mr. Fairlie’s system for one of our metropolitan lines, and we now have to record another success in the same direction. We lately visited the Fairlie Engine and Steam Carriage Company’s AVorks at Hatcham, in order to witness the running of one of two tank locomotives upon the double bogie system. These engines have been constructed for the Nassjo and Oscarsham Railway in Sweden, to the order of Mr. John Morton, who is making the line, and who has also to supply the rolling stock for working it. Mr. Morton adopted the Fairlie system of locomotive after a careful investigation of its working, which fully satisfied him of its merits. The boiler of the engine in question consists of two barrels with a fire-box in the centre, the barrels being 2ft. lOin. outside diameter, and 8ft. 6in. long. The fire-box is oft. 2in. long, and 2ft. llin. wide. Both fire-box aud barrels are made of 3-8in. Low Moor plates, the under side of the parrels being of 7-16in. plates double riveted in all longitudinal seams. The tube plates are 5-8in. thick, and the smoke boxes 3-16in. thick, the latter being of best Staffordshire plate. The inside fire-box is of copper 3-8in. thick, except where the tubes are fixed, where 5-8in. copper is used. The fire-box has a mid-feather or water space across the centre. The- sides and ends of the fire-box are stayed to the outer shell with 7-8in. copper stays; the top is supported by wrought-iron stays placed 4in. apart. There are 70 square feet of heating surface ; the number of brass tubes in each barrel is 109, each ljin. in diameter and 8ft. lOJin. in length. They represent a heating surface of 763 square feet, thus giving a total heating surface of 833 square feet; the grate area is 11 square feet. The engine has four outside cylinders lOin. in diameter with an 18in. stroke ; they are se cured to the frames with 7-8in. bolts. As already-observed, the engines and boilers are carried on two bogie frames, which are of Yorkshire iron. The sides are in one piece Jin. thick, and are formed with horns to receive the axle guards, which are of cast iron. The framing of each bogie has cross stays of wrought iron carrying a cast-iron centre boss, which receives the bogie pin, the head of which forms a saddle upon which the boiler rests. The two bogies are connected together by a strong wrought-iron carrier frame, on which the fire-box is placed. This frame is riveted to the heads of the bogie pins, and to cross stays at each end of the fire-box, and is stiffened with angle iron on either side. Each bogie is carried on two pairs of wheels, forged solid, 3ft. 2in. dia meter, and fitted with steel tyres 3ft. 6in. diameter; the axles are 4Jin. diameter, made of the best Yorkshire scrap iron, and having inside bearings. Although the engine is a double one it is started and stopped with one and the same gear. The tanks are carried over the boiler and under the footplate on each side of the fire-box ; they contain 850 gallons of water, whilst the bunkers are constructed to hold 20cwt. of coal. The weight of the engine in working order is 25 tons, which is equally distributed over the four pairs of wheels. The total wheel base is 19ft. 6in., but the wheelbase of each bogie is only 5ft., which is what we have to deal with in considering the question of running over sharp curves. It will thus be seen that the Fairlie system presents immense advan tages in this respect, curves of very short radii being easily traversed. In addition to this we have the important advantage of weight being made available for adhesion on the rails or tractive power. On the occasion of the recent trial, the engine was run round the railway at the Hatcham Ironworks, which consists of two curves of 50ft. radius joined by two straight pieces. She was put over the line at various speeds, and ran exceedingly smoothly and well. She takes the curves readily at twenty miles an hour, and is stopped and started on them with the greatest facility. The trials were witnessed by the Duke of Sutherland and several other noblemen and gentlemen interested in the improvement of our railways, besides a num ber of our leading engineers, all of whom expressed their entire satisfaction with the principle and its working. This engine is, we believe, the tenth the Fairlie Engine Com pany have built, so that the system is having
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