TRAVELLING CRANE.

111

In many cases, however, the work to be rivetted is spread over so large an area that a travelling crane is necessary, which is hereafter described.

TRAVELLING CRANE AND LIFT.

Drawing No. 63 shows this crane; it can travel from 20 feet to 30 feet along the ground or the shop floor without disconnecting any pipes, and, with a jib of 28-feet rake, a floor area of 4000 square feet is covered. The arrangement of lift is similar to that in Drawing No. 61. The great advantage of this plan is that the work on girders and similar work can be going on in different stages on either side of the rail on which the crane runs, erecting and plating on the one side, and rivetting on the other; or the crane can be used for plating and erecting first, and rivetting afterwards. Pressure mains are led from the "accumulator," between the rails. The jib in Drawing No. 63 is free to revolve all round. A hydraulic lift, carried on the travelling monkey, not only serves to conduct the pressure, but to raise and lower any weight up to 1 or 2 tons. Two of such cranes are often placed at the head of a ship-building slip, and all the floors and frames rivetted up as they pass under on their way down the keel, across which they are laid for rivetting before being up-ended. As soon as the ship is done, the cranes are moved to the next berth, or in some cases placed inside the hold for rivetting up the floor, etc. Ship rivettings, so far as the shell work is concerned, is a problem yet to be satisfactorily solved; but so far back as 1872, in a paper read before the Institution of Mechanical Engineers, at Liverpool, Mr. Tweddell described his mode of rivetting ships' frames, keels, etc., which is now practically carried out, and used by all leading shipbuilders.

PORTABLE RIVETTING PLANT (Drawing No. 64).

The characteristic of this arrangement is that not only is the rivetting machine carried on a crane, but the motive power for driving it also, and since the waste heat from the rivetheating furnaces nearly suffices to drive the pumps, it is evident that, so long as the rivets have to be heated, nothing more economical as to cost of working can well be devised.

The object of this design is to meet cases in which the bridge is to be erected in sites where skilled labour is often difficult to

obtain, and much of the rivetting work is very heavy. This plant has not only been considerably adopted abroad, but also used in England. The first bridge, indeed, ever rivetted by hydraulic machines was thus done in London, in 1872, on the Great Eastern Railway Extension Works at Bishopsgate Street. But little description of Drawing No. 64 is required. All the lifting, racking, travelling, and other movements can, if desired, be done by power from the engines which drive the pumps. The accumulator spindle is utilized to serve as a crane post, and all the gear turns round this. The crane jib is made a great height, on account of doing the deepest girders.

Small hydraulic punching, shearing, straightening, and bending machines can readily be attached to the bed plate, and are very useful; of course the pressure is available to work other rivetters, which, for the time being, may be suspended by ordinary tackle on other parts of the work.

HYDRAULIC PUNCHING AND SHEARING MACHINES.

Drawing No. 65 shows a hydraulic punching, shearing, and angle-cutting machine, similar to those supplied to the Toulon Dockyard, and other places by the Hydraulic Engineering Company, Chester, to Mr. Tweddell's designs. The largest sizes hitherto constructed can punch 11-inch holes in 11-inch plates, and shear plates of 14 inch thick at a distance of 5 feet from the edge of the plates. The advantages of this system come out more prominently as the work to be done becomes heavier. When the plates are in the proper position to be punched, the workman admits the pressure; this is entirely under his control, and the punch cannot descend until he is ready. The pressure cannot exceed the load upon the accumulator; and hence it is immaterial whether there is too heavy a piece of work put in or not, as the machine cannot be strained.

The machine works silently; there is no noise or vibration, and on this account foundations are unnecessary.

As each cylinder with the tool holder attached is independent, an accident to one of them does not cripple the whole machine, as is the case when gearing is used; and as each tool works independently of the other, the man has not to wait until the stroke of the tool at the other end of the machine is completed. Each part of the machine is self-contained, and,

SHEARING MACHINES.

113

if desired, it can be taken into three parts and placed separately about the yard, or taken to where temporarily wanted, and connected to the mains. The facility for putting on special tools or stamps is also very considerable; and the shear blades are so attached that they can very readily be altered to any angle by moving the blocks which hold them.

The valve gear is arranged so that the amount of water used is proportionate to the thickness of the plate punched. The angle and bar cutter is shown placed between the punch and the shears, but of course the combinations are practically endless. A great incidental advantage is the clear headway obtainable for cranes, owing to the absence of belting or shafting.

the

Amongst the other different applications may be mentioned

CHAIN CABLE SHEARING MACHINE (Drawing No. 66).

In this modification of the hydraulic shears just described, the general principle is, of course, the same. The cable, although cut in one stroke, is, by stepping the knife, A, really cut in two efforts, thus allowing the area of the cylinder to be halved, although, of course, doubling the stroke. The same amount of water is therefore used, but considerable structural advantages are secured.

The machine is a double-ended one, and chain cables from inch up to 3 inches in diameter can be cut without requiring any alteration in the knives.

As in all Mr. Tweddell's machines, the return motion is automatic and effected by hydraulic pressure. These machines are in use in most of the principal public chain-testing establishments in this country, and are worked both by pumps direct and also with accumulators.

RAIL SHEARS (Drawing No. 67).

This illustrates another mode of applying hydraulic power by the use of a steam accumulator. This device has been used for many years, the novelty in the present machine consisting chiefly in the use of an automatic cut-off gear, which it is not necessary to describe in detail here. The principle of the apparatus is this: A large steam piston in the cylinder, A, and

I

subject to pressure of steam from a boiler, and having a considerable length of stroke, imparts a proportionately intense pressure per square inch on the fluid in the smaller cylinder, B, placed above it. The water in cylinder B being thus under great pressure, is conveyed through a pipe, C, to the hydraulic cylinder D, with a ram carrying the rail shears, E. The ram in cylinder D having only a very short stroke and a considerable diameter, the power stored up in the cylinder B is applied to great advantage.

Without the intervention of this apparatus, it is clear that with the same steam power an impracticable size of shearing ram would be necessary, as the space through which the tool travels is so limited.

The apparatus illustrated in Drawing No. 67 is intended to be carried in parts on railway trucks from one depôt to another, utilizing the steam from the boiler of the locomotive which draws it. All old rails there accumulated are cut up to scrap, and the apparatus then moves on to the next station, and works off the old rails there.

STAMPING, CORRUGATING, AND FORGING PRESSES (Drawing No. 68).

This press is used for corrugating sheet iron or steel plates for roof-work, and also as a stamping machine for fence pillars, footsteps, etc.

It will corrugate plates 12 feet wide by inch to thick, and could even take in larger sizes.

inch

This class of

machine only shows one of the many applications of hydraulic power. The well-known "Mallet" buckled plates have for many years been so manufactured, and similar machines have been made for stamping plough breasts and shares, and in fact shaping and moulding all descriptions of work. It is impossible to illustrate all these various applications, more especially as very often the chief points of interest centre in the ingenuity displayed in the construction of the necessary moulds and blocks.

Disc railway wheels, threshing machine drum-heads, are also so stamped.

Carried a step further, these machines develop into forging presses, and very good work has already been done in this way.

BENDING MACHINES, ETC.

BENDING AND STRAIGHTENING MACHINES.

115

This is another useful class of machine, and although hydraulic power obtained by means of a hand pump has often been used for this work, the machine shown in Drawing No. 69 possesses some novel features in addition to the quickness of working, due to the use of an "accumulator." The length of stroke of the ram, A, is regulated by means of tappet gear, B, and of course by the same means it can be kept uniform for any work where much repetition is required. The outer abutment blocks, C C, it will be seen, are moved towards and from each other by means of a right and left handed screw, DD, thus keeping their positions relative to the moving block, E, on the ram, A, correct, and capable of adjustment to the greatest nicety. By means of a coupling on the centre of screw at H, each side may, if required, work independently. No breakages can occur should too heavy a beam be put in, as the pressure due to the accumulator cannot be exceeded, and as these machines are made to exert a pressure varying from 10 tons to 100 tons, all classes of work froin small angles 4 inches by 4 inches by 1 inch up to I section of the largest sizes rolled, can be bent or straightened.

FLANGING MACHINE.

Drawing No. 70 shows one of Piedboeuf's machines, which is capable of flanging plates of all forms. These presses have been made powerful enough to flange steel plates 11 inch thick and 8 feet in diameter. The mode of working is as follows. The ram, A, in the main cylinder, A2, carries a table, B, on which is supported a hollow matrix, C, made of suitable form to pass over a fixed die or block, D, but leaving enough space between their respective surfaces all round to enable the plate, E E, to be moulded. The action is a somewhat peculiar one, since the matrix, C C, passes beyond the block, D, leaving the plate on the latter. This being left still hot, easily falls off by its own weight, and is removed. There is, however, a very important matter to be attended to, namely, holding the plate firmly to the upper block, while the matrix, C C, is passing over it.

The four small cylinders, H H, carry a flat table, I I. This