| LEGEND TO THE ILLUSTRATIONS, SEE BELOW Print Specifics:
Notes:
Legend to the illustrations: WINDLASSES and JACKS are simple machines designed for raising heavy weights. The simplest forms of these are too well known to require illustration. A windlass of more elaborate construction is represented in the engraving, where fig. 10 is an end view, fig. 11 a front view, and fig. 12 the bottom frame. The wooden drum a is mounted on an iron axle, which also carries the spur-wheel b, which is driven by the pinion c, the axle of which is turned by the two winches d d' ; the frame B rests on the rollers f f, which may be made to run on a railway. The windlass is used in building and in manufactories, where heavy loads require to be moved from one place to another. In France they are employed, asshown in fig. 10, to lift the bodies of mail coaches, u, off the ordinary wheels, E, and place them upon the railroad trucks, c. The ropes or chains pass down over the pulleys, q q. CRANES have a two-fold motion ; that by which the load is raised, and a rotary motion by means of which it may be deposited in another place. The frame of a crane consists of a post or upright beam, from the upper end of which projects horizontally or obliquely upwards, a beam called the jib, at the end of which the load is raised, and which is supported by a brace or stay. The post turns on pivots at both ends, or sometimes on the lower end only. At the end of the jib is a pulley, over which, in cranes of a simple construction, passes a rope from the load to adrum which is turned by winches, or, when heavy loads are to be raised, by a spur-wheel and pinion, as in the machine last described. Cranes are generally erected on wharves for the unloading of vessels, and they are universally employed in foundries and machine shops, where enormous loads are lifted and moved by means of them. Fig. 6, is a side view of a crane generally used in foundries; fig. 7 is a top view of the same. It is entirely of iron; the frame consists of two plates separated by cross-pieces, and held together by serew-bolts, h h; B is the post, c the stay, D the jib; the gudgeons, p p' of the post turn on friction rollers, as shown in fig. 8. The force is applied at the winches, o, on the axle of the pinion, N, which drives the spur-wheel, M, on the axle of which is another pinion driving the spur-wheel, K, which carries round the drum, L. On the axle of the pinion N is a ratchet-wheel, into which a catch or detent falls to prevent the load from descending when the power ceases to act. The chain passes from the drum over the pulleys, Q and H, to the load. Besides the circular motion about the gudgeons, a rectilinear motion towards or from the centre can be given to the load in this crane by means of the following construction. The pulley, H, is attached to a small truck, G, which can be drawn along the track, T, by means of the rack F; the latter is driven by the pinion, P, which is turned by means of the rope, n n, wound several times around the drum, J, on the axle of P. Another crane, of French construction, composed of wood and cast iron, and intended for raising very heavy loads, is represented in fig. 1, being a view from behind, and fig. 2 a side view; fig. 3 shows the arrangement of the wheels on a larger scale. It is supported entirely at the lower end on the axis A, which is a hollow cast iron cone (a section being partly shown in fig. 2) turning on a gudgeon, B, at the lower end, and at the top in an iron collar, c, which are fastened in a pier of solid masonry. The jib, E, and stay, F, are of wood; the drum, Q, on which the chain, r, is wound, and the wheelwork arms, G G-, attached to the posts are of iron. The operation of the machinery is readily understood from the figure. In order to sustain the load when raised, and to allow it .to descend slowly when desired, a small drum, n, is attached to the spur-wheel, J, having a ratchet-wheel and brake, as shown on a larger scale in figs. 4 and 5. Fig. 9. is a drawing of a very ingenious crane in the machine-shop of Maudslay, in London, which is mounted on wheels in a room used for setting up large engines, and which serves for raising and transporting the heavier parts of the engines, and for adjusting them in their positions. It has two arms, Q Q, which are movable about the bolts, a a, and may be raised or lowered by means of the chains attached at b b and wound around the drum, A, when it is desired to bring the load nearer to or further from the centre of the crane. The drum, A, turns with the cog-wheel, B, which is driven by an endless screw on the spindle, E, which also carries the wheel, D; the latter is driven by the pinion, F, when the spoke-wheel, G, is turned by hand. The load is raised at one arm only, while at the other a counterpoise is suspended, which descends as the load is raised, and vice versa, and serves to establish the equilibrium of the crane. The chains by which the load and counterpoise are suspended are attached to the arms at c c, and passing over the pulleys, H and J, are wound over the drum, K, the axle of which rests in bearings at d, which are set into the post, T. The force is applied at the crank, o, and turns the drum by means of the pinions, e and M, and the spur-wheels, N and L. Martin2001 Satisfaction Guaranteed Policy!
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