Crane (machine)

“ With stiff wooden legs, they swept on in a never-ending race, while a great orchestrion clamoured in wild speed. The summer sunlight sprinkled its gold upon the garnet canopies carried by the tireless racers and upon all the devices of decoration that made Stimson's machine magnificent and famous. A host of laughing children bestrode the animals, bending forward like charging cavalrymen, and shaking reins and whooping in glee. ”

“ For instance, the special derrick or crane trucks which we built are almost certain to be adopted in commercial use. The locomotive crane has always been a useful machine, but its chief use has been in handling heavy materials which were being loaded on or off railway cars. A crane which can be moved rapidly to places where railway tracks are not located should be of almost equal importance. ”

“ A crane is an example of combination of wheel-work used for the purpose of raising or lowering great weights. Fig. 106. represents a machine of this kind. A B is a strong vertical beam, resting on a pivot, and secured in its position by beams in the floor. It is capable, however, of turning on its axis, being confined between rollers attached to the beams and fixed in the floor. ”

“ While the products of the Yale & Towne Manufacturing Company have always consisted chiefly of locks and related articles, they have added since 1876 the manufacture of chain blocks, electric hoists, and, during a considerable period, two lines allied to tool building, namely, cranes and testing machines. This company was the pioneer crane builder of this country, organizing a department for this purpose as early as 1878, and developing a large business in this field, which was sold in 1894 to the Brown Hoisting Machine Company of Cleveland, Ohio. ”

“ But in case the mould about it be so ponderous as not to be remov’d by an ordinary force; you may then raise it with a crane or pully, hanging between a triangle (or like machine) which is made of three strong and tall limbs united at the top, where a pully is fastned, as the cables are to be under the quarters which bear the earth about the roots: For by this means you may weigh up, and place the whole weighty clod upon a trundle, sledge, or other carriage, to be convey’d and replanted where you please, being let down perpendicularly into the place by the help of the foresaid engine. ”

“ She hurried forward through the crowd as if intent upon reaching a distant home, bending forward in her handsome cloak, daintily lifting her skirts and picking for her well-shod feet the dryer spots upon the pavements.
The restless doors of saloons, clashing to and fro, disclosed animated rows of men before bars and hurrying barkeepers.
A concert hall gave to the street faint sounds of swift, machine-like music, as if a group of phantom musicians were hastening.
A tall young man, smoking a cigarette with a sublime air, strolled near the girl. ”

“ A separate donkey engine is provided for feeding the boiler. The truck is furnished with legs under which packings can be wedged so as to relieve the load on the wheels when block-setting. The slings seen under the boiler are for hanging a concrete balance weight; this will weigh about 20 tons. The weight of the crane itself without load or ballast is about 80 tons. The crane was tested under steam with a load of 19 tons with the most satisfactory results; the whole machine appeared to be very rigid, an end often very difficult to obtain with portable wrought-iron structures and live loads. ”

“ Nor, moreover, is it every situation that will allow the Crane-rope to form a right angle with the barrel on which it winds; and when this angle is oblique, the friction must be much increased. The friction arising from the wheels at the top of the vertical crutches might indeed be got shut off, by making the inclined wheel very strong; but this would add greatly to the friction of the lower gudgeon of the oblique shaft, and considerably increase the expence of the Machine. ”

“ What is that strange-looking machine over there? It has three columns which move on circular rails round a table in the centre. Up and down each column passes a stage carrying with it a workman and an electric drill working four spindles. Look! here comes a crane with a boiler shell, the plates of which have been bolted in position. The crane lets down its load, end-up, on to the table, and trots off, while the three workmen move their columns round till the twelve drills are opposite their work. ”

“ Fig. 1. is an Elevation of the Crane. In cranes of the common construction, the beam is a fixture, and is placed at right angles to the upright-shaft; but in the machine represented in this Plate, its attachment is at the lower extremity of the crane, where it is moveable up and down upon a journal or bolt. This crane is therefore termed a Moveable-beam-crane. The moveable property of the beam, in so far as the writer knows, is new, and possesses the advantage of laying any stone within its range perpendicularly on its site. ”

“ The quality of the work is all that could be desired; in some parts, indeed, the use of the felt-packing necessary in hand work has been found to be unnecessary owing to the tight work obtained by hydraulic riveting. One crane with its riveting machine can, in a vessel of moderate size, say 3,000 to 4,000 tons, fully keep pace with the up-ending of the frames, provided it has something of a start. As it advances the lower deck beams are put in place behind it, and the other work follows in order. ”

“ Where goods have to be brought from one particular spot to another, as in fig. 6, the swing crane is used. Amongst cranes may be named the hydraulic lift; this is exactly similar to the hydraulic press, only applied in a different manner, and is used to lift very heavy weights but short distances, as for raising heavy goods on to railway trucks, &c.
CRANKS.
Cranks are bends in the axle of any part of a machine by which an up-and-down motion is converted into a circular or rotatory one, as in the common knife grinder’s machine ”

“ The 25-ton crane is provided with one trolley, having a lifting capacity, for regular load, of 25 tons, together with auxiliary hoist of 5 tons. When loaded, the crane can operate at the following speeds: bridge, 250 feet per minute; trolley, 100 feet per minute; main hoist, 12 feet per minute; and auxiliary hoist, 28 feet per minute.
The power house is provided with an extensive tool equipment for a repair and machine shop, which is located on the main gallery at the northerly side of the operating room. ”

“ But the cattle in the barn were trampling, trampling, trampling, and above this noise could be heard a humming like the song of innumerable bees. The old man hurled aside the great doors, and a yellow flame leaped out at one corner and sped and wavered frantically up the old grey wall. It was glad, terrible, this single flame, like the wild banner of deadly and triumphant foes.
The motley crowd from the garret had come with all the pails of the farm. They flung themselves upon the well. It was a leisurely old machine, long dwelling in indolence. ”

“ When the crane is working the water passes out of the cylinder, a, by the pipe, h, and exerts its pressures on the plungers of the smaller cylinders; and the plunger of the accumulator, in beginning its descent again, moves the lever in connection with the throttle-valve of the engine, and thus again starts the pumps, which therefore at once begin to supply more water to the accumulator. The latter is, however, large enough to keep all the several smaller cylinders of the machine at work even when they are all in operation at once. Fig. ”

“ A six ton steam crane is placed upon the top of the cage which supports the hydraulic apparatus for raising the battering rams, thus permitting them to be easily lifted and replaced.
The dredging machine is also furnished with two screws driven by an engine of 300 indicated horse power, as well as with two independent boilers. Two independent series of pumps, with separate connections, feed the hydraulic lifting apparatus, thus permitting repairs to be made when necessary, without interrupting the work. A special machine with three cylinders drives the pumps of the condenser. ”

“ It is simple, consisting merely of a wheel and axle:
“‘2. It has comparatively little friction, as is obvious from the bare inspection of the figure:
“‘3. It is durable from the two properties above mentioned:
“‘4. It is safe: for it cannot move but during the pleasure [59] of the man, and while he is actually pressing on the gripe lever:
“‘5. This Crane admits of an almost infinite variety of different powers; and this variation is obtained without the least alteration of any part of the Machine. ”

“ There are many other important points of crane construction too numerous to mention here, but it may be said generally that the advent of electricity has tended to increase speeds, and in consequence great attention is paid to all details that reduce friction and wear, such as roller and ball bearings and improved methods of lubrication; and, as in all other quick-running machinery, great stress has to be laid on accuracy of workmanship. ”

“ Even externally the modern electric crane presents an entirely different aspect. We behold graceful steel trellis-work stretched above the hall, and from this is stretched out a slender pair of tongs, which is movable in all directions. The whole mechanism is controlled by a single man. By means of a gentle pressure on the levers, he directs the electric currents and drives the slender steel limbs of the crane to rapid action. [389] Unaided, they grasp the glowing steel and whirl it through the air, while no other noise is heard but the low buzzing of the electro-motors. ”

“ Nearly all recent advances in crane design are the result of the introduction of the electric motor. It is now possible to apply motive power exactly where it is wanted, and to do so economically, so that the crane designer has a perfectly free hand in adding the various motions required by the special circumstances of each case. ”

“ A crane for raising weights, on an entirely new principle—that of the application of the lever, assisted by wedges, instead of the usual plan of wheel and pinion, for multiplying power—has recently been constructed at the West India Docks. The power of two men, with the patent crane, is stated to be capable of lifting from 2-1/2 to 3 times the weight lifted through the same space in a given time, by the best constructed cranes on the old principle of wheel machinery. ”

“ The motor in most common use for electric cranes is the series wound, continuous current motor, which has many advantages. It has a very large starting torque, which enables it to overcome the inertia of getting the load into motion, and it lifts heavy loads at a slower speed and lighter loads at a quicker one, behaving, under the action of the controller in a somewhat similar manner to that in which the cylinders of the steam crane respond to the action of the stop-valve. ”

“ MOVEABLE JIB and BALANCE CRANES.
W. & A. K. Johnston, Edinburgh.
183
“The ‘balance crane’ (Fig. XI-2) was constructed on a new principle for building the upper part of the Bell Rock Lighthouse, when the guy ropes of the moveable beam crane became ‘too taut,’ as sailors express it, or were too near the perpendicular, thereby rendering the beam cranes unstable. To remedy this, the balance crane was so arranged as to be kept in equilibrium by a back weight of cast iron, so adapted as to counteract the varying load upon the working arm or beam. ”

“ The hydraulic crane is rapid in action, very smooth and silent in working, easy to handle, and not excessive in cost or upkeep,—advantages which have secured its adoption in every part of the world. Electricity as a motive power for cranes is of more recent introduction. The electric transmission of energy can be performed with an efficiency not reached by any other method, and the electric motor readily adapts itself to cranes. ”

“ In one minute its scoop can bite out as much dirt as 3,600 men could dig just using their muscles to lift ordinary hand shovels!
The giant shovel is one of the biggest machines ever made, but there’s another that can lift even bulkier things. It is an overhead crane that works in a shipyard.
Often the crane hoists big boilers out of ships so that repair men can work on them. It is so huge that it carries another crane on its back. The piggy-back crane—that’s its real name—reaches down and lifts things off the deck of the ship, too. ”

“ What strikes us more than the supreme exactness with which each does its portion of the work, is the great deliberateness of its proceeding. All the hurry and bustle is above us, caused by the driving-bands from the engine, which keeps the whole machinery of the shed in motion. Suddenly, with harsh creakings, a great overhead crane comes jarring along the bay, drops a chain, grips up a gun-barrel, and, handling this mass of many tons’ weight as easily [Pg 122] as we should lift a walking-stick, swings it off to undergo another process of manufacture. ”

“ In first cost the hydraulic crane has the advantage, but the power mains are much less expensive and more convenient to arrange in the electric crane.
The limit of speed of lift of hand cranes has already been mentioned; for steam jib cranes average practice is represented by the formula V = 30 + 200/T, where V is the speed of lift in feet per minute, and T the load in tons. Where electric Speed. or hydraulic cranes are worked from a central station the speed is greater, and may be roughly represented by V = 5 + 300/T; e.g. a 30-cwt. crane would lift with a speed of about 200 ft. ”

“ In the sketch given above, the entire gantry is shown as made of timber, but iron or steel can be equally well adopted, and continuous masonry or brickwork walls may be built to serve as verticals.
Fig. 448 is a sketch of a small handy crane for warehouse work; it is quick in action, and restricted to weights not exceeding twelve hundredweight. This form of crane may be strengthened to lift still greater loads, but in doing so the additional size of the parts, and the corresponding extra labour [Pg 296] in working, detract from its efficiency as a quick-acting crane for light weights. ”