« iepriekšējāTurpināt »
ternal diameter, 10 inches thick, and weighs 15 tons. It is a perfect mass of cast iron. Allowing for waste, 22 tons of fluid incandescent iron were required for this enormous casting. After being left for 72 hours in the mould in which it was cast, the mould was detached from it. It was still red hot. It was then left to cool, and it was ten days before it was sufficiently cool to be approached by operatives, well inured to heat, for the purpose of detaching from it the part of the sand of the mould which still adhered to it.
The ram, which is the immediate object that receives and transmits the pressure, is also cast iron, measuring 20 inches diameter, and weighing 3 tons 13 cwt.
When the weight and bulk of these working parts of the engine, and the vast force exerted by them, are considered, it will be easily understood that corresponding strength must be provided in the framing and moulding it. The cylinder is enclosed in a cast-iron jacket, bound round by wrought-iron slabs, which being placed around it when red hot, were allowed to cool, and in cooling contracted so as to grasp the casting with irresistible force. The weight of this compound jacket of cast and wrought iron is eight tons.
The cylinder and ram thus enclosed in the jacket rest upon horizontal beams of cast iron, each of which weighs five tons. These beams themselves rest upon compound girders of curious construction, which form the basis and bear the entire incumbent weight of this immense piece of machinery. These girders are composed of plates of wrought iron of an inch thick, alternated with boards of American elm 2 inches thick, the timber and the iron being united after the fashion of a sandwich, and the entire girder being composed of six plates of iron alternated with six interposed boards of elm. This compound beam of wood and iron—the plates and boards being placed with their planes vertical, their edges being presented upwards and downwards-is secured at top and bottom by twelve wrought-iron bars extending the whole length of the beam. The weight of each of these sandwiches is twelve tons.
The means by which the ram is made to elevate the bridge is as follows: to the top of the ram is attached a cross-head of cast iron; the ram, being, as we have stated, a cylindrical rod twenty inches in diameter, is let into a hole of corresponding size made in this cross-head, on which it is securely fastened. The weight of this cross-head is thirteen tons.
To prevent the ram from suffering any lateral strain during its action, the cross-head is made to work on vertical guide rods of wrought-iron, each six inches in diameter, which are fixed in sockets on top of the press. To the cross-head were attached the chains which descend to the level of the water and embrace the tube to be raised.
The greatest weight lifted by the press was 1,144 tons, but it was capable of raising 2,000 tons. The quantity of water injected into the great cylinder in order to raise the ram six feet was 81 gallons. When a lift of six feet was effected, the lifting chains were seized by a set of clamps under the lowest point to which the cross-head descended, and, while they were thus held suspended, the water was discharged from the great cylinder. Meanwhile the lengths of the chains above the clamps were removed, and the chains thus shortened attached to the cross-heads by other clamps connected with the cross-head, and all was prepared for
another lift. In the practical operation of the machine each lift occupied from thirty-five to forty minutes.
Planks of cold iron, of different thicknesses, have been punched by this machine, and it has been found that for the thickness of one and a half inch a pressure is required of 700 tons, and for three and a half inches' thickness, a pressure of 2,050 tons. This being a single press is the largest one yet made.
Model of Patent Locomotive Machinery for working up or down steep inclines from or to Wharfs, &c.-G. D. B. Beaumont, London.
This model only shows the principle of bite for steep inclines; the same principle, with different construction of leverage, is adapted to common roads, and has lately been worked successfully by locomotive steam engines.
Railway Carriage.-Exhibited by the London and Northwestern Railroad Company.
One of the great disadvantages under which the management of the passenger traffic on the railways of the United Kingdom has labored hitherto, is the disproportionate ratio of the dead weight to the profitable weight in the passenger carriages, as commonly constructed. Thus first-class passenger carriages, which will weigh, empty, from four to five tons, will generally be incapable of transporting, when full, more than eighteen passengers, without luggage; while, in our own country, it is well known that railway carriages are worked which transport eighty passengers, with very little more dead weight. An attempt is made to obviate this great waste of power in the form of this new style of carriage. This vehicle, which was constructed at the company's works at Wolverton, besides economizing the dead weight, is also so constructed as to have greater durability and safety in consequence of introducing the use of iron, instead of wood, into the framing and body of the carriage. The sheet-iron which is used for the panelling is corrugated, which, while it increases the strength, gives greater external beauty to the outline and appearance of the vehicle. The carriage is supported by six wheels of peculiar construction, each wheel being formed of wrought iron in one solid piece, tire included-an arrangement which obviously gives greater security against fracture than the common mode of constructing the wheels in parts. The length of the carriage is forty feet, by eight feet in width, and is divided into two first-class bodies, each capable of accommodating eight passengers, and so lofty that a person of ordinary stature can stand erect with his hat on. There are five compartments, each of which accommodates 12 second-class passengers, besides compartments of sufficient magnitude for the luggage of the passengers and accommodation of the guard. Thus this carriage may be regarded as a train in itself, capable of conveying 76 passengers, with their luggage and guard; the total weight of the carriage, without its load, being eight and a half tons. To convey the same number of passengers with the carriage at present in use would require a dead weight of 17 or 18 tons. There are other features worthy of observation in this vehicle. One of these is the contrivance for facilitating the motion of the carriage through curves.
The Locomotive "England."-Built by G. England, New-cross, London.
The great feature in this engine is its great lightness in proportion to its power, and the combination of the engine and tender upon the same wheel; and the purpose in view is to work trains of light weight. Its constructors affirm that it has sufficient power to impel a train of six first-class carriages at a speed of 60 miles an hour, and, if their expectations be realized, it will accomplish this at half the working expenses of the engines now used for such trains. Although it has no tender, it is stated to be capable of carrying a stock of fuel and water sufficient for a stage of 50 miles, so that it would be capable of taking a train from London to York by a feed of fuel and water at three intermediate stations. Small working model of a Locomotive Engine for common roads.—Made by W. Murdock, Birmingham, as far back as the year 1785.
A spirit lamp constitutes the furnace of this machine. The cylinder is attached directly to the boiler, and the piston rod works a horizontal beam, that communicates motion, by means of a crank, to the driving wheels. It is worthy of notice that the once favorite project of travelling on common roads, propelled by steam, has no other representative than this diminutive and original specimen.
Marine Engines, of collective power of 700 horses, designed for driving the screw propeller by direct action-Messrs. J. Watt & Co., London, and Soho, Birmingham.
These engines are arranged to act almost directly on the crank that turns the shaft of the propeller, and the cumbrous beam and connecting rods are dispensed with. The direct action engines seem now to be generally superseding the beam; and in the engines exhibited the great point of competition seems to be the best means by which the action can be directly communicated from the piston rod to the crank. In these large engines of Messrs. Watt & Co. the piston rods work in guiding grooves on the plan which we believe was originally introduced by Messrs. Mandsly & Field, and a short connecting arm communicates the motion to the crank. The cylinders are of large diameter, and short, to adapt them to the direct communication of motion which is facilitated by a small crank. These engines, in construction and workmanship, present an excellent specimen of the perfection Great Britain has obtained in the manufacture of marine engines of great power. The advantage of direct action seems to have been understood in the earliest construction of steam engines, and the plan of applying it was then similar to the arrangement we have been wont to consider new. Sectional models of Steam Engines.-Watkins & Hill, Charing Cross.
By means of these admirable instruments of instruction all the internal parts of the engine may be seen, each part being animated with its proper motion. The engine is supposed to be cut through by a longitudinal vertical plane; one side of the model exhibits the real form of the engine, and the other side exhibits the section showing its internal
mechanism. All the pistons, valves, slides, levers, and other moving parts, move with exactly those motions which they have in the real machine; the motion which in the machine itself is produced by the action, of the circulating fluids, such as water and steam, being produced in the model by mechanical contrivance.
One of these models represents a marine engine, another a locomotive, and the principal one, constructed in brass, and kept in motion by means of a small working model near it, represents a stationary condensing lowpressure engine, with all its appendages, as commonly used in the arts and manufactures.
If the visitor examined carefully the movement of the parts, beginning at the piston, he observed that when that piston begins to descend, the slide which admits steam from the boiler to the top of the piston is open, as are also the passages which communicate between the bottom of the cylinder and the condenser, so that the steam urges the piston downwards against a vacuum. When it arrives at the bottom of the cylinder, he observed the slide, governing the admission and the escape of the steam, to shift its position, the bottom of the cylinder being now put in communication with the boiler and the top with the condenser, and thus the piston will be driven upwards by the pressure of the steam under it. If he then followed with his eye the passages leading to the condenser, he saw the air pump working, and its valves opening and closing, by which the water and air are drawn from the condenser and thrown into the hot cistern. He saw, in like manner, the action of the hot and cold water pumps, the parallel motion, the governor, and, in a word, all the parts of the machine.
An intelligent and attractive observer, having some slight previous knowledge of the mechanical properties of steam, will, by a mere inspection of this model, obtain a more perfect knowledge of the steam engine than could be acquired by days of study in books. For schools and colleges such a model in series would be invaluable.
Patent Safety Apparatus for preventing accidents in descending or ascending Mines.-Messrs. Fourdrinier, Sunderland.
This machine consists of a cage or basket, which can be employed in every way precisely as any arrangement now in use. The cage or basket is attached to guide rods or chains in the shaft, and upon the rope or chain being broken, arms forming powerful levers are liberated, and these are wedged most securely upon the guide rods. The apparatus has no chance of falling more than a few inches after the rope or chain is broken. The stop is most perfect, and so free from any violent action that no danger is to be apprehended from recoil. Another arrangement has been made by which the casualties arising from being drawn over the pullies are entirely prevented.
Self-inking Press.—Messrs. Ransome & May, Ipswich.
This machine has a stationary table for the types. The "tympan," as it is called, which keeps the paper in its place and folds over the types, is withdrawn by turning a winch, and as the paper is removed, the inking roller advances. In this method the types are passed over once by the
roller as the tympan is withdrawn, and again when it is run in with a fresh sheet of paper. All that the pressman has to do is to put in the paper, turn the winch till it is in the proper position over the types, and pull down the handle of the press; by then reversing the direction of the winch the tympan is drawn out, and throws itself back, that the printed paper may be taken away.
Oscillating Engines.-Messrs. Penn & Son, Greenwich.
These manufacturers and engineers have obtained great celebrity for their oscillating engines. The ones here exhibited are of 12-horse power, and are contrived to act directly on the crank without the inter. vention of a connecting rod. The cylinders, being balanced on pivots, oscillate as the shaft revolves, and thus apply the power to turn the cranks at all points of bearing. This form of engine is not confined to the size of those exhibited, for the same makers are now constructing a pair of engines of 500-horse power for the Great Britain. There is also a feed engine for pumping water into the boilers of steam vessels when the large engines are not at work. The cylinder and pump of this machine are placed opposite each other, the piston rods being connected to the same cross head, which works in a guide, and has a vertical slot in which the crank revolves without being connected. The force of steam in the piston of the small auxiliary cylinder acts directly on the piston of the pump, and communicates rotary motion to the crank in the slot. When the pump is worked by hand, the turning of the crank gives a direct reciprocating movement to the piston without the intervention of any connecting rod.
Model of a Submerged Paddle Wheel to work wholly or partially under water.-J. Pym, 52 Threadneedle street, London.
This paddle wheel consists of a number of double blades, each resembling a flat oar radiating from the centre, the upper and lower parts being placed at right angles to each other. A screw in the axle of the wheel takes into threads in the centres of the blades, by which they have a rotary motion imparted to them independently of the revolution of the wheel. When resistance is required, the flat sides of the oars are turned to strike against the water; and when resistance would check propulsion, the blades are turned edgeways. This propeller, therefore, would act entirely under water; though, when partially above the surface, the resistance to the ship's motion would be less.
Self-acting feathering Paddle Wheel.-Mr. Jones.
This paddle wheel deserves notice from the simplicity of the arrange. ment and the effective way in which it prevents retarding resistance. The floats turn on pivots, and have stays at the back to prevent them from turning round when they are required to act against the water; but as soon as they have passed that point, and their further resistance would be detrimental, they turn and meet the water edgeways.