Hydraulic machine

“ In hydraulic motor machines a quantity of water descending from a higher to a lower level, or from a higher to a lower pressure, drives a machine which receives energy from the water and applies it to overcoming the resistances of other machines doing work.
In the next general class, work done on the machine by a steam engine or other source of energy is employed in lifting water from a lower to a higher level. A few machines such as the ram and jet pump combine the functions of both motors and pumps. ”

“ Consequently, when the piston ascends, it no longer forces the water into M, the air of the reservoir, by the pressure it has received, reacts on the liquid, and raises it in the tube D, until the piston again descends, so that the jet is continuous.
Hydraulic Machine Tools. Probably in no department of engineering has the use of hydraulic power met with more success than in its application to certain machine tools. ”

“ From the earliest ages, a vessel suspended by a cord, has been used by all nations—a device more simple and more extensively employed than any other, and one which was undoubtedly the germ of the most useful hydraulic machine of the ancients. ”

“ In connection with their engineering works they carried on the manufacture of lead pipe by hydraulic pressure. The engine which drove a large section of their machine tools also drove the hydraulic pumps for this manufacture. It was a very trying service. The resistance was very heavy and came on and off the engine instantly. The action of the common governor was not prompt enough to control it, and they had to employ a man handling a disk valve with a very short motion. ”

“ Of appliances utilizing the forces of Nature, perhaps the simplest efficient machine is the hydraulic ram. While other machines for lifting water are composed of two parts, namely, a motor and a pump, the ram combines both in one apparatus. It is a self-acting pump of the impulse type, in which force is suddenly applied and discontinued, these periodical applications resulting in the lifting of water. Single-acting rams pump the water which operates them; double-acting rams utilize an impure supply to lift a pure supply from a different source. ”

“ During his apprenticeship, on 9 May 1865, he took out a patent (No. 1282) for a portable hydraulic apparatus for fixing the ends of boiler tubes in tube plates. The pressure of water was from one to one and a half ton on the square inch. When the force-pump did not form part of the machine itself, the connection was made by a copper pipe, which was flexible to allow of the movement of the machine. The results were so encouraging as to suggest the employment of hydraulic power for machines used in boiler construction (Min. of Proc. of Institution of Civil Engineers, lxxiii. 65) . ”

“ Thirty-four years’ practice has proved these ne plus ultra Hydraulic Machines, in their average results, to be cent per cent the most effective and durable, the best and cheapest of any in the world; they are made to discharge from half a pint to a ton weight of water, at a single clip or stroke, and are readily applied to any motive power to draw or force water, air, or any not rapidly injurious fluids, in any quantity, or to any height or distance, for any purpose, by John Shalders, Manufacturer, and Sole Proprietor. ”

“ The best machines are those of the hydraulic riveting system, which combines all of the advantages and avoids all the difficulties which have characterized previous machine systems; that is to say, the machine compresses without a blow, and with a uniform pressure at will; each rivet is driven with a single progressive movement, controlled at will. The pressure upon the rivet after it is driven is maintained, or the die is retracted at will. ”

“ The machines comprise those for punching, shearing, angle cutting, plate bending, and riveting, and the author referred to is high in his praise of the superior efficiency and economy of the hydraulic system, as exemplified in practice. One or two of [134] the leading advantages of the system may be here summarised. Hydraulic machines do not consume any power at all during the interval between employment, and the power can be applied at any moment without preparatory consumption, and stopped equally quick. ”

“ Hydraulic cranes for coal or grain hoisting have a high efficiency when well designed, but it is now very usual to employ grabs to save the labour of filling the buckets, and their use lowers the efficiency, expressed in tons of coal or grain raised, by 33% or even 50%. When hydraulic machines are fully loaded, 50% to 60% of the indicated power of the central station engine is often utilized in useful work done with a radius of 2 or 3 m. ”

“ 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. ”

“ The hydraulic ram is a machine that gets its power from the momentum of running water. A ram consists of a pipe of large diameter, an air chamber and another pipe of small diameter, all connected by means of valves to encourage the flow of water in two different directions. ”

“ The shaft is the piston-plunger of a very long cylinder connected by pipes to pumping engines and hydraulic machines. It and the mass it bears up serves as a reservoir of energy. If the pumping engines were coupled up directly to the hydraulic tools, whenever a workman desired to use a press, drill, or stamp, as the case might be, he would have to send a signal to the engine-man to start the pumps, and another signal to tell him when to stop. ”

“ In this case the head driving the hydraulic machinery is artificially created, and it is the convenience of distributing power in an easily applied form to distant points which makes the system advantageous. ”

“ Sir William Armstrong has applied hydraulic power to cranes and other machines in combination with chains and pulleys. His hydraulic crane is represented by the diagram, Fig. 169, intended to show only the general disposition of the principal parts of this machine, which is so admirably arranged that one man can raise, lower, or swing round the heaviest load with a readiness and apparent ease marvellous to behold. ”

“ An engine working the pumps for 8 or 10 hours out of the 24, is reckoned adequate to the winning of a new colliery, which reaps no advantage from neighbouring hydraulic powers. In the course of years, however, many water-logged fissures come to be cut by the workings, and the coal seams get excavated towards the outcrop, so that a constant increase of water ensues, and thus a colliery which has been long in operation, frequently becomes heavily [970] loaded with water, and requires the action of its hydraulic machinery both night and day. ”

“ Here it is proper to mention once for all, that the pressure for the hydraulic machines is obtained not only by natural heads of water, or by forcing-pumps worked by hand, but very frequently by forcing-pumps worked by steam power. ”

“ The screw is fixed at one end in a socket and is turned round by a long bar of iron or wood, and as the “worm” works in a corresponding hollow screw which is fixed, it ascends or descends slowly but with great power. But by far the most powerful contrivance of this kind is the “hydraulic” press; this machine is not only used as a press, but also to raise great weights, and for many other purposes. The hydraulic press consists of a strong iron cylinder having a solid piston exactly fitting to it, this piston is raised by forcing water under it by means of a pump ”

“ It requires to have all rivet holes drilled, and it must be carefully annealed, though the writer is informed by Mr. Edwin Danks, of Oldbury, that steel makers often prefer to have their plates either worked cold or at a red heat, and not in the intermediate condition. Drilling machines especially designed are now used. Hydraulic machines of greatly improved construction have come into use for facilitating the operations in the boiler yard. ”

“ Hydraulic machines for these purposes have the peculiar and distinct advantage of direct action of the pressure on the moving rams, resulting in simplicity of construction, slow and steady movement of the working parts, absence of mechanical brakes and greatest safety in action. ”

“ The pressure is always on the outer end of the piston, so that the rods, C, are in compression, and take up their own wear. This engine is well adapted for transmitting pressure to appliances which are worked intermittently, as, owing to the great speed at which it can be run, it will not only save the loss from friction (where gearing is employed) , but will also reduce the friction in the machine itself by enabling the gearing153 for increasing speed to be dispensed with. The production of this simple hydraulic rotary engine led to its wide application to capstans. ”

“ Water-pressure has sometimes been applied to operate machines which are worked continuously and not intermittently, and to continuous working rotary machines. This is unwise, for in applying hydraulic power to the continuous working of shafting or shop tools, the amount of power developed by the hydraulic engine cannot be varied to suit the work to be done, neither can the speed be regulated with sufficient nicety. ”

“ Water under pressure conveyed in pipes is a convenient and economical means of transmitting energy and distributing it to many scattered working points. Hence large and important hydraulic systems are adopted in which at a central station water is pumped at high pressure into distributing mains, which convey it to various points where it actuates hydraulic motors operating cranes, lifts, dock gates, and in some cases riveting and shearing machines. ”

“ In the Newcomen or “fire engine,” as it was called, the power is produced by the pressure of the atmosphere forcing down the piston in the cylinder, on a vacuum being produced within it by condensation of the contained steam by means of cold water injection. The piston-rod is attached to one end of a lever, whilst the pump-rod works in connexion with the other,—the hydraulic action employed to raise the water being exactly similar to that of a common sucking-pump. ”

“ In steam engines a piston is alternately pushed forward and back in its cylinder by steam; and by means of the rod to151 which the piston is secured, motion is communicated to a crank and fly-wheel, and through these to the machinery to be driven: it is the same with pressure engines when used to move other machines, except that instead of the elastic vapor of water, a column of that liquid drives the pistons to and fro.
Note.—“The hydraulic engine of Huelgoat, in Brittany, is used to drain a mine; is single-acting, and acts directly to lift the piston of the pump. ”

“ Answer.—There are several terms common to hydraulics and steam; the steam boiler might be called an accumulator of power; there is a slide-valve in hydraulics as in the steam engine, to admit the power and to allow the exhaust to escape; there are stop-valves and intermediate valves in hydraulics, as in steam pipes, also air-vessels in each: there are suction and delivery pipes and valves in each, and relieve valves also in each; there is a cylinder in each in which the power is concentrated; there are reversing levers in a hydraulic crane, as in a steam crane. ”

“ In a common pump water is lifted by operating a plunger in and out of a cylinder. It will be readily understood that the operation may be reversed, and if power is applied to the water to force it through the pump, it will make the plungers move in and out of the cylinder. In the hydraulic variable speed gear the driving shaft is made to operate a set of little pumps which are connected to a second series of pumps that act upon the driven shaft. Instead of water oil is used, and the oil pumped by the driving pumps is forced into the driven pumps. ”

“ When the machines to be tested require more than the power of seven horses that the motor gives, the persons interested furnish a movable engine, which, placed under the annex, actuates the driving shaft. Alongside of the main building there is a ring for experimenting upon machines actuated by a horse whim. There will soon be erected in the center of the grounds an 18 meter tower for experiments on pumps. Platforms spaced 5 meters apart, a crane at the top, and some gauging apparatus will complete this hydraulic installation. ”

“ The engineer sets the pump in action, the water is rapidly forced into the cylinder, the piston is thrust inwards, and the strain upon the chain begins; the engineer then cuts off 330the water supply from the larger force-pumps, and the smaller pair go on until the strain becomes sufficient to raise the weight, and then the person in the weighing-room, by pulling a wire, opens a valve in connection with the hydraulic cylinder, which allows the water to escape, and the strain is at once taken off. ”

“ For instance, there are machines for bending pipe, for curving railroad rails, for punching holes in metal, for pulling wheels off their shafts, for jacking up heavy weights, for baling cotton, paper, and other materials, all of which operate on the same principle as the hydraulic press. Water pressure is supplied sometimes by a hand pump, sometimes by a [100] power-driven pump, and sometimes it is taken from a reservoir in which compressed air imparts the requisite pressure to the water. ”