US63816A - Improvement in steam safety-valves - Google Patents

Description

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JOHN scHAFFEaor s'r Louis, Missonni, iissiowos 'ro SAMUE BAX'rnR, or SAME PLAoE.

Letters Patent Na. 68,816, (Zated April 16,'1867.

MPROVEMENT IN STEAM SAI'ETY-VALVES.

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'To ALI. WHOM IT MY ooNoERN;

Be it known that I, JOHN'SOHAFFER, of the city and county of St. Louis, and State of Misso'uri, have invented a new and useful Improvement in Lock-up Safcty-Valves; and I do hereby declare that the following is a full and clear description thereof, reference being had to the accornpanyin'g drawings, and to the letters of reference marhed thereon. i i

This invention relates, firstly, to the arrangement of the safety-valve, which has two seats, one above and the other below it, the upper seat being used, when the valve is open, for the purpose of excluding the escaping steam from the interior of the box or case wherein the levers and weights are locked up, which are thereby rendered more free in their action and less liable to rust. The invention also relatcs to the arrangement of the levers and adjustable fulcra, whereby vthe levers are left free to yield to the Vertical motion of the valve-stem `without jamming or becoming disarranged during the opening of the valve, and thereby endangering the action of the safety-valves. 'A

Figure 1 of the drawings is a Sectional elevation of the improved valve.

Figure 2 is a transverse sectional elevation.

Arepresents the shell of the hoiler to which this Safety-valve is to be applied. B is the Safety-valve' Chamber, within which is placed the valve O, which has a seat at c, where the steam escapes from the boiler when thepressure is toohigh, and also a seat' at cl, where the steam is shut out from' the,.box D which contains the levers and'weights which are to' keep down the Safety-valve. When the pressure in the boiler is notabove the required standard the valve will rest upon its seat o, but as sgon as there is pressure enough within the boilcr to raise the valve it will, by such pressure, be forced up against the seat cl. I einploy the well-known arr'angexnent of'compound lcvers, E and F, as clearly shown in fig. 1. The lcver E has its fulcrum at e in the adjustahle standard E', and the lever F at the pointin the adjustable standard F'. The valve-stcm 0/, which holds thc valve down, is fitted into a socket, 02, in the bottom of the level` E. The levcr E rests under the bottom of the levcr F, in a circular bearing drawn from the centre el. The benring point-5,8, el,, and cz, are all placed in the same straight linc, x x, and consequently, when the valve rises, the points crz anda1 will rise in ncarly a Vertical direction, and without bccoming cramped or ininmed during the motion. This is a matter of vital importancc, as the slightest disarrangement iu this particular will endariger the Safety of the boilcr the valve is designed to protect. The standard' F' consists of two links, having pivots atandl, so as to allow them a pendulous motionabout the point fl, in order to allow the levcr F a longitudinal motion. This will prevcnt the levcr E froin becoming jainmed at ex during the upward inotion of the valve; for it is evident that the utcr end ofthis lcverv will describe an are of a circle drawn from the centre e. In order to coinpensate for the occasionnl grinding in of the valve C, and the consequent shortening of the stcm C', I make the standards E' and F' adjustablc as to height by the use of the scrcw-nuts ezz, so that either standard may bc set higher or lower, as occasion may requirc. This is also a very important arrangcinent in view of thc frcquent shortcning Or lowering the stcm C' will bc subject to. The valve Cis guided above and below by the slidcs ca 8*, so thut its position ou either seat, c or ul, will bo certain.

A couiiuonditliculty with safety-valvcs, as at present constructed, consists in the inability of the valvc to close itself after it has once been opencd and the steam is cseaping through it. This difliculty ariscs from the fact that the dead pressure of the steam only is cxerted upon the vnlvc until it is opcncd; but :is soon as it is opon the momentum of the moving steam will havc to be overcome before the valve can bc closed. As' this valve is of that lock-up variety which has recently been ordered to bc adoptcd by Congress, and is entircly out of the control of the'cngineer, it is very important that it should be so arranged as to close itself as soon ns the pressure is reduced to the proper point; and in ordcr to`accoinplish this result I lower the cnil of the levcr F, to which the weight W is applied, so that when the said levcr is raiscd up to its greatest nltitudo it will not bc raised higher than a horizontal line, y y, drawn across its top edge, and consequently the weight W will not with a greater force to pull down the levcr when it is up than when it is down. This is c'vident from the fnct that the weight W, in rising, travels through an are' of 'a circlc, and, with the above conditions fullillcd, it w-ill be fm'ther from the fulcrum of its level` When up than When down. The box D shuts down tightly to the bedplate D', where it may be locked fast. The steam pipe G eonveys the escape steam out of the valve-Chamber without having it pass into or through the box D.

Having thus fully deseribed my invention, what I cloim, is-- v The arrongement of the double-seated Safety-valve O with reference to the cas'e D, and the levers E and F, substantially os and for the purpose set forth.

JOHN SCHAFFER. Witnesses M. RANDOLPH, GEO. P. HRRTHEL, Jr.

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