Valve (mechanical)

“ Therefore, if we accept the definition that a valve is a mechanical appliance for controlling the flow of a liquid or a gas, strictly speaking no such thing as a "valveless" motor exists. Two-cycle motors are sometimes said to be valveless because of the fact that the movement of the piston automatically regulates the flow of the exhaust and intake gases, but in this case the piston is in reality the valve. ”

“ As the water is incompressible, slide valves must have neither lap nor lead, and piston valves are preferable to ordinary slide valves. To prevent injurious compression from exhaust valves closing too soon in rotative engines with a fixed stroke, small self-acting relief valves are fitted to the cylinder ends, opening outwards against the pressure into the valve chest. Imprisoned water can then escape without over-straining the machines. ”

“ If the trouble is in the valve or steam chest, you had best take it off and have the valve seat planed down, and the valve seated to it. This is the safest and best way. Never attempt to dress a valve down, you are most certain to make a bad job of it. ”

“ A number of small valves and perforations in the partition sheet between the water and steam compartments, will remedy that hitherto very general annoyance of water rising to and through the valves, which is occasioned by pressure of steam upon the surface of the water, and when one large valve is opened, the pressure is partly removed from the water immediately under it, consequently the water rises through the valve. ”

“ A valve consists essentially of any simple hinged substance, arranged so that it may rise or fall, alternately opening and closing an aperture. A mere flap of leather, nailed on one edge, serves as a tolerably effective valve. At least one of the valves used by Ctesibius was a hinged piece of smooth metal. A piston fitted in a cylinder supplies suction when the lever is raised, and pressure when it is compressed, alternately opening the valve and closing the valve through which the water enters the tube. ”

“ When the valve moves a sufficient distance to either fide of the central position, steam enters one end of the cylinder from the valve-chest and escapes from the other end of the cylinder through the cavity of the valve into the exhaust port. The valve is generally moved by an eccentric on the engine shaft, which is mechanically equivalent to a crank whose radius is equal to the eccentricity, or distance from the centre of the shaft to the centre of the eccentric sheave. ”

“ The non-return valve is simply a mushroom or ball valve without handle, lifted off its seat by gas passing from underneath whenever the pressure of the gas exceeds the weight of the valve, but falling back on to its seat and closing the pipe when the pressure decreases or when pressure above is greater than that below. ”

“ The valve rod must be accurately guided so as to avoid side strains; the valve must fit accurately to its seat and to the cover plate, and the adjustment so made that the valve slides freely at first, being steam tight, and yet allowing room for lubrication to enter. When the travel of a valve, balanced by a cover plate, is varied to alter the point of cut off, the construction must be such that the ends of the valve at the shortest stroke pass over the ends of the seat and cover plate faces, or otherwise the middle of the seat and cover plate faces will wear hollow. ”

“ You will readily observe that anything that will cause the cut off valve to reach a certain point earlier in the stroke will bring about an earlier cut off as it hastens everything all around. This is the plan pursued in the Buckeye, in which the governor, of the shaft type, turns the eccentric forward or back according as the load demands. Then, in addition, the valve is balanced partially, the attempt not being made to produce an absolutely balanced valve, on the ground that there should be friction enough to keep the surfaces bright and to prevent leakage. ”

“ The Corliss Valve.—The valve itself is of the rotary type, as shown in Fig. 75, in which the port A goes to the cylinder, and B is the passage for the steam from the boiler. The cylindrical valve body C has within the aperture B a gate D, one edge of which rests against the abutment through [162] which the port A is formed, and this gate has within it the bar E which is connected with the crank outside of the casing. ”

“ The length of stroke must be kept long enough for the movement of the piston to knock over the valve. The valve on the Rio Tinto machine is a piston, or spool valve; on other machines the valve is of the plain D-slide valve type. The Rand "giant" drill has a device to reduce the total air pressure on the back of the valve. ”

“ The pressure of the water from the source of supply, admitted by means of proper valves, gives to the pistons this reciprocating motion. The valve gear between the two parallel cylinders is so arranged as to cause the pistons in one cylinder to move in an opposite direction from those in the other. A rotary valve is used for both cylinders, situated between and below them, being circular, or funnel-shaped, having holes, or ports, in its side for the induction and eduction of the water into and out of the cylinders, and being crowned with a bevel-gear to give it a circular motion. ”

“ Low pressure starting valve, used for piston hydraulic cylinders in which the lifting is performed by the down stroke of the piston rod, and in lowering, the valve allows the water to pass from above to below the piston, the water being exhausted from below the piston on its down stroke when the valve is in the position shown. ”

“ The specification then minutely described an automatic relief or safety-valve, and added: 'To enable the valve to be screwed down to bring all practical pressure upon the pump and hose in the trial of an engine, there is a hole, d', drilled through the upper part of the screw-cap, D, and valve-stem, d. When the valve is down in its seat, for the reception of a pin, by the insertion of which the valve-stem and cap can be connected rigidly, so that by slightly turning the cap the valve may be screwed down close to its seat. ”

“ The proper and accurate functional operation of the valves is as necessary to successful motor operation as the proper adjustment of a hairspring is to a watch, for if a hairspring becomes impaired in any way, a watch will not keep correct time. This is the case in a motor when a valve becomes impaired. The valves in a motor, therefore, must be considered the most vital part conducive to successful and economical operation of the motor. ”

“ In lieu of the weighted lever valve gear for single cylinder water pressure engines, the engine may be arranged to compress a spring during the stroke, which at the end of the stroke shall be released, and by its expansion reverse the valve. ”

“ By this time he had reached the car, and—through sheer blundering luck—at once stumbled upon the seat of trouble: a clogged valve in the carbureter. No serious matter: with the assistance of a repair kit more than commonly complete, he had the valve clear in a jiffy. ”

“ The inlet and exhaust valves are located in the cylinder head, and both valves are mechanically operated by one push-rod and rocker, radial pipes from crank case to inlet valve casing taking the mixture to the cylinders. The exhaust valves are placed on the leading, or air-screw side, of the engine, in order to get the fullest possible cooling effect. ”

“ The spindle carrying the valve has an eye in its upper extremity, to which a cord is attached for the purpose of opening the valve when the water is to be admitted, and on releasing the cord, it again closes by its own weight. ”

“ Hydraulic plug or spindle valve and seating; all seatings for high pressure should be narrow and hard.
1636. Duplex or Ramsbottom safety valve; each valve serves as a fulcrum by which to lift the other. One fulcrum point should be jointed to the lever and the latter move in a vertical guide, or else the point of attachment of the spring to the lever be placed below the level of the valve seatings. ”

“ VALVE GEAR.--Thomas E. Evans, William R. Thomas, and Joshua Hunt, Catasauqua, Pa.--This invention relates to a new and useful improvement in the mode of operating valves of steam engines, more especially designed for pumping engines, but applicable to other purposes or to valves of steam and water engines generally. ”

“ In order to reduce the loss by slippage several valves are used instead of a single valve of equal area. A flat disc valve will rise a distance equal to one-fourth the diameter of the port or of the opening in the seat to discharge the same volume of water that can flow through the port in the same time. In practice the rise exceeds this proportion of one-fourth a trifle, owing to the friction of the water, and this is especially true at high speeds. ”

“ A thin film of the grinding compound is evenly applied to the seating face of the valve head, a screw driver or ratchet fork is set in the groove on the head of the valve, and the handle rolled between the palms of the hands, covering about one-third of the distance around the valve seat ”

“ When the lever is in the last notch the valve has its full travel. When the lever is in the center notch the valve has no travel at all, and no steam can get into the cylinder; on the other side the lever allows the valve to travel gradually more and more in the opposite direction, so reversing the engine. ”

“ The hydrostatic valve consists of a flexible diaphragm, one side of which is in contact with the water outside, so that since the pressure increases with increasing depth, it is bent inwards more or less as the depth varies. ”

“ The face of the cylinder on which the valve works is raised a little above the metal around it, both to facilitate the operation of forming the face and with the view of enabling any foreign substance deposited on the face to be pushed aside by the valve into the less elevated part, where it may lie without occasioning any further disturbance. ”

“ When a slide-valve is actuated by an eccentric connected directly with the rocker-arm or valve-stem, the point of cut-off caused by the extent of lap, remains the same till a change is made on the valve, or on the throw of the eccentric, unless an independent cut-off valve be employed. ”

“ The speed controlling device of the style A governor shown in Fig. 571 is simple and can be so set as to prevent the pump from racing, regardless of the drop in water pressure. Surrounding the upper end of the valve stem is a coiled spring, which acts as a cushion for the valve and stem, and by the use of a spring, the stem can be quite small thus reducing the friction in the stuffing-box to a minimum. ”

“ The method in which this animal fills its float is curious, it throws it back, and gradually lifts the lip of the valve out of water, until the valve stands vertical, it then closes the valve tightly round a globule of air, around which it folds, by means of the most complex and delicate machinery. ”

“ The Rotatory valve is simply a 'fourway stopcock turning in a cylindrical case in the plane of the instrument, two of its four ways forming part of the main channel, the other two, on its rotating through a quadrant of the circle, admitting the air to the bypath.' This gives great freedom of execution, but is far more expensive and liable to derangement than the Piston valve. ”

“ A bucket pump with a foot valve and no discharge valve would, however, suffer more from a leaky gland than if it had a discharge valve and no foot valve, because the air would, on the ascent of the bucket and the closing of the bucket valve, pass to the suction side of the bucket and impair the vacuum. ”

“ The valve proper is made of a single piece of steel with openings of ample size, so that there is no danger of clogging with the heaviest fuels. As the valve only lifts 1
16 of an inch, the amount of work required to operate the valve is very small. ”

“ Globe Valve.—A globe valve has the advantage that the valve is forced against its seat by the pressure of the wheel, differing from the gate valve, that depends on the pressure of the fluid to keep it tight. ”

“ Dividing this impact or slam on numerous valves of low lift, tends to break up and lessen the shock, therefore with valves of the size and style used in fire-pumps, other things being equal, the less they have to rise and drop to let the water through them, the less will be the valve slam. ”

“ A valve larger than an automobile. The small, sixteen-inch valve on the side of the large valve is what we call a by-pass valve, and which, when opened, relieves the pressure, so that the large gate can be opened more easily. ”