Check valve

“ 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. ”

“ 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. ”

“ Look for air leaks around the spark edge openings, and be sure that all valves seat gas tight. Always be sure that the auxiliary air valve remains closed at low speeds, as a valve that opens at too low a speed will surely cause misfiring as it dilutes the mixture. ”

“ A dead weight safety valve is one in which the valve is held to its seat by dead weight, the objection to which is, that when the vessel rolls the effect of the weight or weights upon the valve is diminished; hence under heavy rolling the steam may blow off at a less pressure than the valve is set for.
A lock up safety valve is a dead weight safety valve, the top of whose spindle is provided with a cast iron cap or bonnet with two handles on. ”

“ 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. ”

“ 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. ”

“ A broken exhaust-valve stem or a broken or displaced spring will often be difficult to observe; a valve may have stuck open through stiffness or through something getting under its seat. The exhaust-valve gear should be carefully watched to see that all the valves work regularly and to their full extent. ”

“ 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. ”

“ Too small a clearance should be avoided for the reason that the valve stems expand with the heat and will lift the valves too soon, or even permanently until readjusted. Broken valve springs will cause trouble, or lost keys that retain the valve spring washers. ”

“ Now if your engine is all right, you can run the pressure up to the point of blowing off, which is from one hundred to one hundred and ten pounds. Most new pop valves, or safety valves, are set at this pressure. I would advise you to fire to this point, to see that your safety is all right. It is not uncommon for a new pop to stick, and as the steam runs up it is well to try it, by pulling the relief lever. If, on letting it go, it stops the escaping, steam at once, it is all right. If, however, the steam continues to escape, the valve sticks in the chamber. ”

“ The bolt B has a very small hole bored through it from end to end. When the vacuum is broken slowly, the pressure falls in D as fast as in the pipe; but a sudden inrush of air causes the valve A to be pulled off its seat by the diaphragm C, as the vacuum in D has not been broken to any appreciable extent. Air then rushes into the train pipe through the valve. It is thus evident that the driver controls this valve as effectively as if it were on the engine. These "emergency" valves are sometimes fitted to every vehicle of a train. ”

“ The valves of a marine engine that are worked by hand are, the stop valves for letting on steam from the boiler, the safety valve, which is lifted to see that it is in proper working order, the Kingston valve for letting in the circulating water, the blow through or starting valve for warming the cylinders and starting the engines. The valve for adjusting the rate of boiler feed has its lift adjusting screw operated by hand. The slide valve may also be operated by hand before the engine is started, or it may be operated by a steam reversing gear. ”

“ It thus takes four strokes or two revolutions of the shaft to complete the Otto cycle, the cylinder being used alternately as a pump and a motor, and the engine, when working at full load, thus gives one impulse for every two revolutions. The valves, which are all of the conical-seated lift type, are four in number—charge inlet valve, gas inlet valve, igniting valve, and exhaust valve. The igniting valve is usually termed the timing valve, because it determines the time of the explosion. ”

“ 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. ”

“ It is free from all Lever Joints and other parts which might become clogged; and as there is always a slight pendulous motion in the weight by the action of the water in the boiler, the spherical surfaces of the valve and its seat are thus ever kept in perfect order. As soon as the desired pressure of steam has been reached, and the gravity of the weight overcome, the valve rises from its seat, and gives perfectly free egress to any farther accumulation of steam. It is really quite a treat, in its way, to observe this truly simple and effective Safety Valve in action. ”

“ 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. ”

“ The gasoline adjusting valve is in the passage between the float and mixing chambers. The main or initial air inlet is in the side, the air being drawn through the mixing chamber, and past the spray nozzle. The auxiliary air inlet is a simple valve, opening inward, and held against its seat by a coil spring, the tension of which is adjustable. The pressure in the mixing chamber being reduced in accordance with the increasing speed of the engine, the valve is opened more and more as the atmospheric pressure against the outer surface of the valve overcomes the tension of the spring. ”

“ Fig. 40a
Having once thoroughly grasped the important part the cams play in the working of the engine, it will be an easy matter to adjust the valve settings, and to keep them adjusted correctly. The effect of a wrong setting will then be strikingly apparent. On small engines a separate cam to operate the gas valve is not a necessity; and the practice of fitting [Pg 73] the gas valve spindle (or the pecker, the effect would be the same) with a device for increasing or diminishing its length, is also unnecessary and unsound. ”

“ If the engine has been run for any length of time, you will always find the trouble in one of these places, but if it is a new one the governor valve might fit a little tight in the valve chamber and you may have to take it out and use a little emery paper to take off the rough projections on the valve. Never use a file on this valve if you can get emery paper, and I would advise you to always have some of it with you. It will often come handy. Now if the engine should start off at a lively gait and continue to run still faster, you must stop at once. ”

“ 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. ”

“ The slipping of the eccentrics is about the only cause for a valve working badly. You should therefore keep all grease and dirt away from these marks; keep the set screws well tightened, and notice them frequently to see that they do not slip. Should they slip a I/I6 part of an inch, a well educated ear can detect it in the exhaust. Should they slip a part of a turn as they will some times, the engine may stop instantly, or it may cut a few peculiar circles for a minute or two, but don't get excited, look to the eccentrics at once for the trouble. ”

“ 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. ”

“ 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. ”

“ During the ordinary driving ranges this valve controls the amount of fuel being used, thus providing all the economy possible. This valve is entirely automatic and requires no adjustment.
The passage-way from the mixing chamber to the intake manifold is controlled by a butterfly valve which is called the throttle-valve and is connected to the throttle-lever on the steering wheel as well as to the foot accelerator, its position determining the amount of gas and air or mixture being fed the engine. ”

“ The moment at which an automatic valve opens is governed partly by the tension of its spring; if it is too strong, greater pressure will be required to open it, and it will close sooner than if the tension is light. Accurate adjustment of this spring is necessary in order that the charge may enter the combustion space without delay, and continue to enter as long as possible. The opening and closing of mechanically operated valves depend on the shape of the cam, and not being affected by the more or less uncertain action of a spring, they are more positive in action. ”

“ When any difficulty occurs with a car many drivers at once accuse the electric ignition, when it exists, and next the valves, for the default. The unfortunate valve comes in for a great deal more abuse than it deserves. The less grinding they are given the better. When the operation is necessary of course it must be done. If the car is used daily, for say eight hours, and the oiling of the cylinders has been properly adjusted and not too profuse, it will be sufficient if the valves are removed weekly, to be wiped over with an oily rag, and then cleaned with a little heavy petroleum or benzine. ”

“ This test should be tried occasionally with a full head of steam on, to assure of the piston rings and valve being tight, as leaky pistons and valves are very wasteful of steam, sometimes causing priming, and greatly diminishing the power of the engine. Never run your engine with leaky piston or valve. ”

“ Some carburetors are provided with an adjustment by means of which the "delicacy," or ease of opening, of the auxiliary air valve may be regulated. This may be done by means of a nut and screw which will increase or decrease the tension of the controlling spring. If this spring is set with a high tension, the auxiliary valve will act only when the motor is exerting great suction, or at fast speeds. ”

“ 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. ”

“ A is the suction valve for opening and closing the connection to the manifold through which a vacuum is extended from the engine manifold to the gasoline tank. B is the atmospheric valve, and permits or prevents an atmospheric condition in the upper chamber. When the suction valve A is open and the suction is drawing gasoline from the main supply tank, the atmospheric valve B is closed. ”

“ Although the same principle underlies all these methods, i.e. the lengthening of the main column of air by the addition of other lengths of tubing, the valve itself constitutes a radical difference, for, the adjustment of crooks demanding time and the use of both hands, they could only be effective for the purposes of changing the key and of rendering a multiplicity of instruments unnecessary. The action of the valve being as instantaneous as that of the key, the instrument to which it was applied was at once placed on a different basis ”

“ With the gas, as with any other kind of engine, the valve settings are of primary importance. On very small engines it is often the case that only the exhaust valve is operated mechanically.
Again, there are several well-known makes which operate the gas and exhaust mechanically while the air valve is opened by suction alone. Though opinions differ as to which is the best course to take, there can be little doubt that, with all three valves mechanically operated, a greater nicety of adjustment is obtainable than would be otherwise possible. ”