US1986415A

US1986415A - Valve operating mechanism

Info

Publication number: US1986415A
Application number: US710409A
Authority: US
Inventors: Henry F Schmidt
Original assignee: Westinghouse Electric and Manufacturing Co
Current assignee: CBS Corp
Priority date: 1934-02-09
Filing date: 1934-02-09
Publication date: 1935-01-01
Anticipated expiration: 1952-01-01

Description

Jan. 1, 1935. H. F. SCHMIDT 1,986,415

VALVE OPERATING MECHANISM Filed Feb. 9, 1934 s Sheets-Sheet 1 FIG. 1.

Fica. 3. FIG. 4.

QTNEQSES: INVENTOR M v HENRY F. SCHMIDT C7. 5; I BY a 75,

ATTORNEY Jan. 1, 1935. H. F. SCHMIDT 1,986,415

VALVE OPERATING MECHANISM Filed Feb. 9. 1954 s Sheets-Sheet s INVENTO HENRYBSc DT ATTORNEY Patented Jan. 1, 1935 T OFF-ICE VALVE OPERATING MECHANISM 'Henry E. Schmidt, Lansdowne, Pa.,assignor to Westinghouse Electric & Manufacturing Company; East- Pittsburgh, Pa:, a corporation of Pennsylvania j Application-February 9, 1934, Serial No. 710,409

' 18 Claims, (erase-e) My invention-relates to-valves and-valve operating mechanism'for regulating the speed 'of prime 'mover apparatus, for example, elastic fluid turbines; and ithas for a broad 'object to provide. apparatus ofthis character whi'chis of improved constructionand arrangement" of parts, and also one' -which effectively. controls the prime mover apparatus throughoutitslspeed' V length of l movementrequired to operate the primary element be kept at a small value.

range. v y

Apparatus of this character heretofore known" tome usually comprises a valve body; a=va1ve in the body and including a stem extending exteriorly "thereof; a relay for opening 1 and closing the valve including a secondary "element conarrangement 'operates well when the main valve nected to the valve' stem and a primary elementmovable to *regulate the applic'ationof 1 an op-- crating force to th'e secondary element; and a" follow-up mechanism for re'storingthe primary-- element to neutral 'position 'upon movement'of' the main valve in either direction to terminate movement of r the latter. 'The follow-up mechanisrn is usually in the form via lever connect ing the valvestem and primaryelementand including 1. a fulcrum vi element about which the #:lever rocks.

Depending upon the desired effect; initial" movement of the-primary element to provide movement of the secondary element "and-main valve in=tl1e desired 'directionyhas' been effected in' prior-apparatusof this" type in avariety of ways.

For example, initial movement 'of the primary element may be effected by variations" in a governing force which is afunctionof the speed of the prime moverand'in-such-cases the governing force is opposed bya spring, the-defiection of'which-may be varied manually to-effect a variety of speed adjustments.-" The fol-; low-up mechanism-usually acts-=through the spring to return the primary element-to neutral position. Anotherexample of priorineans for effecting initial movement"of-theprimary element to eithermain-valve openingposition or closing position is by a simple manually operated control means; Astill further example is a combinationof the governor and-the manual control.

In prior art structures 'of this type,;where" it is'desired to regulate the speed of the turbine byvarying the defiection of the -governor spring-to" uohange the speed setting of the governor, or where it is desired to regulate the speedby mov-' ing the primary element in a mainvalve opening or closing direction; movement of the pi'i- -movement cfthe fulcrum elementof the follow A further advantage of such an arrangement, which is particularly applicable tothe type employing a governing spring, is that only -a small length of governing spring-is required. Such an is away from its seat; However, withsuch a structure, as the main valve approaches its seat,

a poor regulation is hadbecause the amount of -movement of the main valve required to move the primary element the short distance back to neutral position produces too great achange in the flow oi: elastic fluid to the prime mover.

*It is therefore,afurtherand more specific object of my invention to provide, in .a valve operating mechanism, for a decreasing ratio of main valve movement to primary element movement as the main valve approaches its seat so as to give a closeand effective regulation at such positions, and'toprovide foran increasing ratio of main valve movement to primary element movement as the main valve leaves its seat so as to maintain the advantage of a small size of primary element and a short governor spring.

Itcis sun a further object of the present in-.

vention to combine the manual adjustment feature utilized in valve operating mechanism of this -character with the feature of varying the ratio of primary element tomain valve movement sothat asthe position of the adjusting element is changed to move the primary element in either direction to vary the position of "the main valve, the ratioof primary element movement to main valve movement will be changed to correspond to the new position of the main valve.

The above objectsare attained according to one embodiment of my invention by providing a longitudinally disposed slot in the follow-up lever, inplacing the fulcrum element in the slot 'and in providingfor manual movement of r the fulcrumelement along the slot in sucha manner that as the fulcrum element approaches the primary element the ratio of main valve movement to primary element movement increases and-at the-same time the primary element is moved in the direction to effect an opening movement of the main valve, and conversely as the fulcrum element is moved away from the primary element to decrease the ratio of main valve movement to primary element movement, the primary element is also moved in a direction to close the main valve.

Another object ofthe present invention is to provide a structure which is comparatively cheap and at the same time is capable of regulating prime movers utilizing elastic fluid at relatively high temperatures. I accomplish this object by providing a mainvalve body of cast steel capable of standing up under the high temperatures, a relay mechanism of cast iron which is comparatively cheap to manufacture, and in securing the two together by steel rods which can be readily tapped into the cast iron relayand then welded to the cast steel valve body. The rods in addition to being strong provide a connection which occupies a small amount of space and thereby offers the maximum of accessibility for assembling and adjustment and the small cross section of the steel rods reduces the transmission of heat from the valve to the operating mechanism to a minimum. In cases where a cast steel valve body is not needed, only the bonnet thereof may be made of cast steel and the rods welded thereto in the same manner.

These and other objects are effected by my invention as will be apparent from the following description and claims, taken in connection with the accompanying drawings, forming, a part of this application, in which:

Fig. 1 is an elevation showing my improvement as applied to a steam turbine.

Fig. 2 is a transverse vertical section through a valve and relay for operating the valve of an elastic fluid turbine constructed in accordance with my invention;

Fig. 3 is a fragmentary sectional view taken on the line IIIIII of Fig. 2 andillustrating the connection between the main valve stem and follow-up lever; a

Fig. 4 is a fragmentary sectional view taken on the line IV7-IV of Fig. 2 and illustrating the connection between the follow-up lever and normally-movable fulcrum element; and

Fig. 5 is a view similar to Fig. 2 illustrating a modified form of my invention.

Referring now in detail to the construction illustrated and particularly to the embodiment shown in Figs. '1 to 4, inclusive, I have shown my invention as applied to a conventional type of steam turbine 10, to which motive steam is supplied by a pipe 11. Flow of steam to the turbine is regulated by a main valve 12 mounted within a valve'body 13, which latter is preferably formed of cast-steel in order that it may effectively stand up under high temperatures of steam.

The valve comprises a stem 14 extending exteriorly of the body and connected to a relay indicated. in its entirety by the reference The relay is preferably disposed within a cast-iron casing 16, which is supported from thecast steel valvebody 13 by means of steel rods 17 suitably tapped as-indicated at 18 into the relay casing and welded, as indicated .at 19, to the cast-steel valve body.

The relay'comprises a primary or pilot element 20, a secondary or operating element 21, and a follow-up lever 22 connecting the primary element and steam valve and including a fulcrum element 23 about which the lever rocks,

The secondary element is connected to the stem 14 of the steam valve for moving the latter to regulate the flow of steam to the turbine. The primary element serves to regulate the application of an operating force to the secondary element. The follow-up lever 22 is moved about its fulcrum element 23 by the main valve to restore the primary element to neutral or cut-off position upon movement of the main valve in either direction.

While, so far as certain of the broader aspects of the present invention are concerned the relay may be of any suitable type, I prefer to use a relay operated by fluid under pressure. As shown in Fig. 2, the secondary element 21 comprises an operating cylinder 24 formed in the casing 16, and an operating piston 25 movable within the cylinder 24 and connected by a rod 26 with the valve stem 14. The primary element comprises a pilot valve 27 slidably mounted in a stationary bushing 28 within the casing 16 and is movable to regulate the application of an operating fluid under pressure to the secondary element.

Downward movement of the operating piston 25 in a direction to close the main valve is effected by means of a compression spring 29 disposed between the upper side of the operating piston and the relay casing 16. Upward movement of the operating piston to open the main valve is effected by; fluid under pressure admitted to the operating cylinder beneath the operating piston and; opposing the force of the spring 29. The fluid is admitted through a port SO inthe lower portion of the cylinder which communicates with one end of a passage 31 drilled or coredin the relay casing and the upper end of this passage communicates with an annular series ofports 32in-the pilot valve bushing 28.

Thepilot valve bushing 28 is also provided with a second annular series of ports 33 below the ports 32 and communicating with apipe 34 which supplies operatingfluid under a pressure,

which, in this case, may be oil from any suitable source, for example, the oil may be supplied by a governing oil line 35 (Fig. 1), which latter is connected to the discharge of a governor pump 36 of the impeller type operated by the turbine shaft 37. The pilot valve bushing is also provided with a third annular series of ports 38 above the ports 32 and connected to a suitable discharge pipe 39.

As shown, the pilot valve 27 is of the piston type and includes a head portion 40 and a skirt portion 41. Two annular recesses 42 and 43 respectively, are provided on the exterior of the 7 shown in the drawing, the ports 32 will be placed in communication with the ports 33 by the annular recess 42 and as a result operating oil under pressure will flow into the lower portion of the cylinder and oppose the spring 29 with sufiicient force to raise the piston 25 and open the main steam valve 12. On the other hand, should the pilot, valve be moved downwardly from the position shown, the annular recess 43 inseam willnrprcvide communication betweeni portsz'csz and ports 38 and oil I will escape from the" cylinf dei' 24i i to the discharge pipe- 39 and thereby struction' isiLespeciallyiuse'ful in marine installantionsiwhe'rein it is :ldesiredqto control the turbine in the low speed or man'euver-ingrange: di-

rectlyiby thand and at the same'itimeit is de- -:sire'd to have governor control for the turbine-in i-thei rupper-i -speed mange). .One N example of i this type of construction isdescribed and claimed in crny:icopendingapplicationg Serial No. 545,603 .filed June 19; 1931 and assigned to'the' Westinghouse 1 Electric & Manufacturing Company.

A compression 1 spring a 45? engages at one end thereof the; under v1 face ofv-ithe head portion-s40 iofth'expiloti valve andiengagesi at its other-end anaabutment'z m-formed zonitheupper end of a :plun'ger element 481 slidably mounted in thecrelay :casing 316. The :spring': 45 surrounds a rodt48 xfixedl atcone end: to;the plunger Hand the other end thereof slidably fitting an ."opening 149 through ithe head 'portion 40. :The upperoend ioflithe "rod?48i isnscrewthreadediand a :pair of niit'si- 50,; one if or: looking the other at "anyv given i pos-itiong won the rod, are :threaded :thereonat *the topzside of'thexhead portion 10 and serve the dual tunction of providing forichangin'g the iniztialidefiectioni of i the compressionspring 45; and also; :due to* their engagementlwithithehead portionceog serve to' pullzthe pilot valve sdownztupon aacdownward movement ofiq the? plunger 47: The plunger isvpivotallyaconnected to one end. of the rfollowi-up-llever 22. i to r :i-The pipe 35=whichdelivers| governing oil under pressure =from the governor pump 36 :driven 'by :theturbineshaft, is connected to aichamber 51 above the" head portion 740.1 Hence: the. upper face of: the head portion 40: 'iszsubjected to the governing oil pressure q generated :;by' v thepump :36; :this; pressure-"being: opposed: by :ithe compression spring r 45 :engaging the under side. of the head: portion As the impeller i pumpv is t driven by the turbine shaft; athepressure iofitheicoil in pipeii35 and" in:the;chamber:51 willnvary as the square of the speed of i the turbine. i Y

r The position; of atheunuts'rfih on therrod AB ideterminesthe initial deflection of the compression spring 45; and hence" determines :the' minimum speed; of the-turbine and'corresponding; governing oil pressure-required-to"'move the; pilot avalve down relative to the} plunger 47. For. speeds below this minimum the-movement of the pilot i valve is-effected only; by the;- positiont of the plunger i V i i V :s-As stated, the plunger 47 is connectedto the main valve-12.; by means of afollowaup lever 22. As shown in Figs. 2, 3,-and4; thefollow-uplever comprises a pairl of like bar'ss5'5 vheld in spaced

rel'ation'by bolts

56 and 57. The. bars are pivoted at one? of theirends to a pivotpin 58 carried-by the plunger element '.:.47 and are pivotally and slidably connected at 'their otheren'd to thevalve stem 14. 1 The latter: connection is effected, as will be "seen from examination of Fig; 3, by spaced rollers i 5'9 -and' connected to thevalve stem and engaging rails'lfil and 62, respectively, which extend from and l are-rigidly secured i to 'the inner 'sides of the bars 55. The

rollersl

59 and 60=are mountedon:

trunnions

63 and 64,

respectively;-carried-by the coup-ling 65; which i.

'connects the valve-stem 14 andpperating piston rod I 26. A tension coil spring 66 is connected at one end-to therelaycasing 16 and at the other endtc the spacing bolt 5'7' and thereby serves to maintain the

rollers

59 and 60 and r'ails fil and 62 in contact.

"The-fulcrum element 23 of-the lever 22 iscarried by' tlie lower and outerend of a' manually movable arm 67. As will be seen from an exam-- inationof Fig. li th'efulcrum'element is in' the 'form of spaced rollers 68 fitting-in aligned slots 69 formed,respectively, 'in the bars 55 and extending -longitudin'ally thereof The rollers are carried by thelower end-0t the operating arm Ghahdsuch arm is-fixed atits -upperend to a control shaft 70 -=rot'atably mounted l in spaced cars '71 -''which depend from the relay casing. Any-suitable means, such as ahand-operated leVer IS-may be provided for-rotating the shaft and thereby moving :the rollers'in the slots 69. Movement of l the operating shaft 'IO J will i cause the axis of -the fulcrum element 23 to: move-in an 'arc of a circle. The dotted line arepresentsthe center-line or the groove 69 and the dot-and-dash line b represents theare of travel for the fulcrum ela vment 23 to" the right ofthe position: shown in "Fig. 2, the are of travel ior thefulcr-um element toth'e left oi the position shown-in that figure being' coincidental with:the center line a.

-Should the fulcrum element be moved to the left as viewed in Fig. 2, no movement will be imparted t o thelever 22or plunger iles the arc of moveinent of the f ulcrum element iscoincident with-the centenline a. On -the other hand,

shouldthe fulcrum elementube-imoved to the right the lever 22 will be moved-in .a counterclockwise -direction about its-pivotal and slidable connectionwith thestem 14 a distance depending on the. distance hetweenlines wand b,

thus movingthe plunger 47 and pilot valve '27 upward-the*same distance. The distance -between lines ct -and b becomesgreater as the right-handendofthe slot is approached. Hence,

the plunger ti -and pilot valve2'l isimovedupward a progressively increasing amount as the tulcrunrelement approaches. the right-hand end of 1 the slot.

An auxiliaryloil-line isrprovided'which conh'ects-withthe pipe 34. Oil under pressure from anysuitable sourcelnot shown) is supplied by the line"-'75. A 'valve 76 inthe line 75 and a valve"-77in the pipe 34 servetoiconnect' the .port's' 33 with either the auxiliary-oil line '75 or with the governing oil pipe 35.

When it is desired to start theturbine .the auxiliary line75 is connected to pipe 34 by opening the=valve '76 and closingsva'lve :77. After the tu'rbine speed'issufiicient togenerate sufficientoil pressure in=the line. 35 to operate the i I piston 25,'thefl'va1ve '77 may he opened and-the valve 76 closed.

Asmallmovement of the fulcrum element to the right, as-viewed in Fig. 2;will result in an upward' movement of-the plunger element 47 and pilot valve'27 and -cause operating oil to how fromthe' port 33*through the recess 42 to theport 32; and; from the latter; through thepassage 31, to the 1 under-f ace of i the operating piston 25,

whereby 'oil pressure below I the latter causes" upas is the case with prior apparatus.

ward movement of the piston to open the main valve 12. Movement of the main valve 12 in an opening direction will cause the'follow-up lever 22 to rock about its fulcrum 23 and pull the plunger 47 and pilot valve 27 back to neutral or cut-off position. The amount of movement of the main valve required to move the pilot valve back to neutral position depends upon the relative lengths of the two lever arms, one lever arm being the distance between the fulcrum element and the pivotal and slidable connection with the valve stem 14 and the other lever arm being the distance between the fulcrum element and the "pivot 58.

, Further movement of the fulcrum element to the right will result in the pilot valve 27 being moved up again and in more oil being admitted beneath the operating piston and consequently in the main valve being opened still wider. For this more advanced position of the fulcrum element, more movement is required by the main valve to move the pilot .valve back to neutral position because the fulcrum element has moved over further andthe lever arm between the fulcrum element and the pivot 58 has become less and the other lever arm greater. Thus, the ratio of pilot valve movement to main valve movement decreases as the main valve leaves its seat and increases as the main valve approaches its seat. Less movement of the main valve is required to move the pilot valve back to neutral position as the main valve approaches its seat. Hence, closer regulation is had when the main valve is adjacent its seat, where increments of movement thereof cause greater changes in steam flow and turbine speed than are caused with the valve away from its seat.

Movement of the fulcrum element further and further toward the right will result in the main valve 12 being opened wider and wider and in the turbine speed being increased. When the speed of the turbine increases to a point where the resulting oil pressure in line 35 and chamber 40 is greater than the initial deflection of the spring, determined by the position of the nuts 50, downward movement of the pilot valve will be effected by the governing oil-pressure on the top of the pilot valve. The spring 45 will then act as a governing spring, and, for this speed range, movement of the fulcrum element will serve to change the speed setting of. the governing spring, and not in a direct manual movement of the pilot valve, as was the case where the speed of the turbine was below this range.

It will be observed that the minimum ratio of pilot valve movement to main valve movement ishad at the higher speed, and in the governing speed range. Therefore, with my apparatus, a minimum length of governor spring is required, and a small travel of piston valve and consequently a small size of piston valve is required, However, at the same time, my apparatus, due tothe varying of the lever arm ratio, provides a close regulation when the valve 12 is adjacent its seat.

Referring now to Fig. 5 of the drawings, it will be observed that I have shown a modified form of construction for controlling the flow of steam to a turbine, the principal difference being changes necessitated by positioning of the fulcrum element to one side both of the operating cylinder and of the pilot valve, instead of therebetween, as in Fig. 2. As in the previously described modification, I provide a main steam valve 12 disposed within a cast-steel valve body 13a and having. an operatingstem 14a extending .exteriorly of the valve-bodyand connected by a connected to an operating piston 25a movable in j-. an operating cylinder 24a. formed in, a relay casing16a formed of cast iron. Also, as in the previously described modification, the cast-iron casing 16a is supported from the cast-steel valve body 13a by steel rods 17a, and the piston 25a is moved down in the cylinder 24a by a spring 29a and is moved upward by operatingoil under pressure opposing the spring pressure and admitted by port 30a from a drilled groove 31a connecting at its upper'end with ports 32a in a pilot valve bushing 28a.

In this modification, the discharge ports 38a in the pilot valve bushing are provided below the ports 32a and the inlet ports 33a are provided above the ports 32a. The operating oil is supplied to the ports 33a by the pipe 34a and the discharge pipe 39a connects with the ports 38a. The pilot valve 27a is movable within the bushing 28a and is. provided with annular recesses 42a and 43a on its exterior face separated by a piston portion 44a. Also, inthis modification, thev recess 42a which serves to connect the ports 32a with the operating oil ports 33a, is above the piston portion 44a; and the recess 43a connecting the ports 32a with the discharge ports 38a, is

below the piston portion 44a.

The governing oil from pipe a is supplied beneath the head portion a instead of above as in the previously-described modification, and the governing spring 45a is a tension springinstead of a compressionspring and connects a spring holder 80 secured to the head portion 40a by a threaded extension 81 and nut 82 and a spring holder 83 screwed to a screw-threaded portion 84 on a plunger 47a. The spring 45a surrounds a rod 85'which is an integral extension of the plunger 47a and engages at its upper end the spring holder 80. The spring holder 83 is in the form of a plunger and fits the cylindrical inner surfaces of the lowerend of the bushing 28a.

The spring 45a will hold the spring holder 80 hard against the end of the rod 85 until the speed of the-turbine is such that the pressure of the governing oil will overcome the force of the spring and move the piston valve 27a with respect to the. plunger 47a. The initial deflection of the springl45a, and hence, the governing and hand control speed ranges of the turbine, are determined by the position of the spring holder 83 on the portion 84; and this position may be varied by screwing the spring holder up or down on the portion 84. As will be readily seen, the principal difference of the construction of the pilot valve and governor spring of Fig. 5 over the construction shown in Figs. 1 to 4 is that, in Fig. 5, the spring 45a is a tension spring and 'in Figs. 1 to 4, inclusive, the spring 45 is a compression spring.

As in the previously described modification, a follow-up lever 22@ connects the plunger 47a and the valve stem 14a, and the lever 22a comprises spaced bars a connected at one end by a pivotal and slidable connection with the coupling 650: on the Valve stem 14a, and also connected to a pivot pin 58a carried by the lower ment, instead of being disposed between themain valve and plunger as in Figs. 1 toe-is disposed inFig. 5, at. the -side of the plunger 4711 which is awayfrom thevalve vstem 14a.

The fulcrum element 23a is movable along the slots 69a by an .a'rm. 67a fixed at its lower end to a shaft v0.1, which is operated-in any suitable manner, asioy a hand-operated lever 78a). The centerlineof the slots 69a. is indicated by 'the' admitted beneath the piston 25a from the port 30a, drilled groove 31a, ports32a, recess: 42m

ports. 33a andpipe 34a. '.The resulting upward movement of the piston-25a acts to open the valvelZa and move the .lever 22a .lupward about the .fulcrum.23.a and carry therewiththe plunger 47a and pilot valve 27a back to neutral or cut-L olf position. Further movements of the fulcrum element 23a to the left will .result .in increased opening movements of the-main valve 12a, and

the operation of. the valve operating mechanism will remain the. same until the turbine speed reaches the governing range, where movement of the fulcrum element will then change *the'setting on the governing spring.;45a .as the previously described modification.

' Movement of the fulcrum 'elementfrom a position corresponding to an open position of the main valve toxthe right or bazck toward the.

position shown, will result in an upward movement of the pilot valve from itsrleutralipposition and in theescape' of operatingloil from beneath the piston25a1throughport 130a, drilled groove 31a, ports 32a,recess 43a and discharge ports 38a and discharge pipe 3.9a; As .:a result,

the main valve 12a willjbe movedtoward closed position carryingdown with .it. the left-hand end of lever 22a. Downward movement of the lever 22a will cause the pilot valvealso to be moved down to its neutral position. l

. As in Figs. 1 to e inclusive, the construction shown in Fig. 5 provides for .adecrease in the ratio of main valve movement to. pilot valve movement as themain valve approaches its seat soas toprovide close regulation "of the main valve for positions thereof. close toits seatwherea given movement of. the steam valve produces a greater change in steam'admission than is had whenthe valve is separated from its seat a substantial distance.

ment to pilot. valve movement increases. so :that

at the -higher turbine speeds andin the govern-; ing speed range the ratio is quite large,:whereby only a smallsize pilot valve and a small length governor spring is needed. 1

lever 22a and thevalve stem 14a and the distance between the fulcrum element and'the pivot pin 58a. .In the closed position the ratio .of. lever arm lengths is shown as being approximately 2 to 1. In the wide open position the ratio is shown asbeingapproximately/l to 1. Obviously,

the structure may be designed to give 'a smaller ratio at the closed position and a higher ratio at. wide open position, if. it is desirdgDue to- Also, as; the main valve 120/ leaves its seat the ratio of main valve; movethe character of the lever shown in-Fig. 5, the

lower limit of design could not belessthan 1 to 1. For a large number of cases, sufficient latitude of design is permittedby the construction be at pointsin the-slot .69 to the left of the position shown.

While I have shown my invention in several forms, it will be obvious to those skilled in the art that it is not so limited, but is susceptible of various other changes. and modifications, without -departing fronrthe spirit thereof; and I desirefltherefore, that only suchlimitations shall be placed thereupon as are imposed by the prior art or as are specifically set forth in the appendedcl'aims. I t

111. The combination with a valve and its seat, otarelay including a secondary element connected to the valve,'a primary element movable forcontrolling the .applicationf .of an operating force to the secondarywelement, and :means responsive to. movement of. the valve for restoring the primary element to. neutral position in order tos'terminate movement of. thesecondary ele ment; .andimeans for'moving the primary elementandadjusting said restoring means so that the 'maximum ratio of primary element movement. to secondary element movement occurs with-thevalve at its seat and so that the ratio diminishes the more the valve is separatedfrom itsseatni l l 2. Apparatus included in claim 1 wherein the restoring means is a lever connecting the valve and primary element and having a fulcrum elementand wherein'the means for moving the primary .element and for adjusting "the restoring means comprises a device for moving the fulcrum element along the lever and providingfor increasing degrees of movement of the primary element. toward itsvalve-opening position as the fulcrum element approaches the primary 'element.;..:.

.3. The-combination with a connected to the valve, a pilot valve controlling the. admission and exhaust .of motive fluid to and 1 from the operating cylinder, follow-up mechanism arranged between .the connected.

main valve and operating piston and the pilot valve for restoring the latter to neutral position upon. movementof the main valve, and

meansrfor moving the pilot valve and adjusting the; ratio. of follow-up-movement so that the ratio of main valve and operating piston movement to pilot valve movement is a minimum with the valve at its seat and increases with movement, or the valve away from its seat.

he respective lengths of the twoarmsrof the lever 2211 are the distance betweensthe fulcrum element 23a and the, connection between; the

4. Apparatus according to claim 3 wherein the follow-upmechanism includes a lever connecting the main valve and pilothvalve, and wherein the pilotvalve moving means includes a fulcrum for saidlever movable therealong to effect movement of the pilot valvevand at the same time to vary the ratio of pilot valve movement to main valve and operating piston movement.

. 5. The combinationwithamain valve and its seat, of .a. relay for controlling movement ofJthe main valve and including a secondary element connected tocthe valve, a primary element movmain valve and its seat, of :an operating cylinder including a piston able to control the application of an operating force to the secondary element, and a follow-up mechanismfor restoring the primary element to neutral position upon movement of the main valve, the latter including a lever connected to the; main valve and pilot valve and having a.

longitudinally disposed slot therein and a fulcrum element in said slot; and control means for effecting, simultaneously, initial movement of the primary element and variations in the ratio of main valve movement to primary element movement; said last-named means including an element connected to the fulcrum element and movable to'elfect movement of the latter along theslot' in the lever.

6'. Apparatus according to claim 5 wherein the control means provides for movement of the axis of the fulcrum element in an arc of a circle and the'slot in the lever diverges away from the arc. ofymovement of the axis of the fulcrum element as the latter approaches the primaryielementu '7. Apparatus according to claim 5 wherein the slot in theilever and the fulcrum element are disposed between the main valve and the primary element.

8. In valve operating mechanism, the combination with .a valve, a servomotor connected to the valve for operating the latter, a movable element for controlling the application of an operating force to the servomotor, of a follow-up lever connecting the valve and movable element, for restoring the" movable element to neutral position in order to terminate movement of the servomotor, a fulcrum element for the follow-up lever between the valve and movable element,

and control means for moving the fulcrum element along said lever to secure movement of varying degree of the movable element whereby the application of operating force to the servomotor is regulated and the ratio of valve movementto control element movement is varied.

9. In valve operating mechanism the combination with a valve, a servomotor, connecting means between the valve and servomotor whereby the latter serves to open and close the valve, and a movable element for controlling the application'of an operating force to the servomotor for operating the latter; of follow-up mechanism connecting the valve and movableelement for restoring the latter to normal or neutral-position upon movement of the valve and including a lever having a fulcrum between its ends, the ends being connectedrespectively to the valve and movable element, and means providing for the movement of the fulcrum from a mid-position on the lever toward the end connected to movable element in the direction to secure move-' ment thereof toefiect closing movement of the' main valve, and wherein for the first part of the movement of the fulcrum toward the movable element, movement of the latter is directly effected and for the last part of fulcrum movement toward the movable element a variation in application of the governing force to the movable element isv effected.

11, In valve operating mechanism, the combination with a main valve, a servomotor including a fluid-operatedv cylinder anda piston within the cylinder connected to the valve for opening and closing thelatter, a pilot valve movableforcontrolling the application of an oper-. atingv fluid to the piston, of a follow-up lever connecting the mainvalve and pilot valve for. restoring the pilot valve to neutral position in order to terminate movement of the piston, a fulcrum element for the lever, and means providing for adjustment of the fulcrum longitudi nally of the lever. 1

12. In a valve operating mechanism, a main valve, a servo-motor, a pilot valve for admitting and exhausting motivefiuid to the servo-motor,

valve is closed and the non-coincident portion of the slot diverging from the path of movement of the fulcrum pin so that, with movement of the pin toward the pilot valve to increase the ratio of main valve movement to pilot valve movement, the servomotor is operated to move the main valve in an opening direction and so that, with movement of the pin along the non-coincident portion of the' slot toward the coincident portion thereof to decrease the ratio of main valve movement to pilot valve movement, the servomotor is operated to move the main valve in a closing direction.

13. The combination with a turbine provided with an admission valve and means for developing a fluid pressure force which is a function of the turbine speed, of a servomotor for opening and closing the admission valve, a pilot valve for controlling the admission and exhaust of motive fluid to and from the servomotor to motivate the latter, said pilot valve having a piston face subject to said fluid pressure, a spring exerting its force against said pilot valve in a direction opposed to that of application of fluid pressure force, means for storing energy in the spring anclaway from the reciprocable member, and a lever pivotally connected to the admission valve and to the reciprocable member and. having a slot within which the pin is disposed and extending longitudinally thereof, said slot diverging from the path of movement of the pin when the pin andlever are in such relative positions that the admission valve is closed so that, with movement of the pin toward the reciprocable member to increase the ratio of main valve movement to pilot valve movement, the servomotor is operated to move the main valve in an opening direction and so that, with movement of the pin in the other direction to decrease the ratio of admission valve movement to pilot valve movement, the servomotor is operated to move the admission valve in a closing direction.

14. The combination With a turbine provided with an admission valve and means for developing a fluid pressure force which is a function of the turbine speed, of a servomotor for opening and closing the admission valve, a pilot valve for controlling the admission and exhaust of motive means opening direction, a fulcrum pin, means providing for movement of the pin toward and from the pilot valve in a predetermined path, a lever pivotally connected to the admission valve and to the reciprocable member and having a slot within which the pin is engaged and extending longitudinally thereof, said slot diverging from the path of movement of the fulcrum pin when. the pin and lever are in such relative positions that the admission valve is closed so that, with movement of the pin toward the reciprocable member to increase the ratio of admission valve movement to pilot valve movement, the servomotor is operated to move the main valve in an opening direction and so thatwith movement of the pin'in the other direction to decrease the ratio of admission valve movement to pilot valve movement, the servomotor is operated tosmove,

ing piston and main valve, the pilot valve having I a piston face; means providing a governing fluid pressure varying with the speed of the prime mover; means providing communication of such governing fluid with the piston face of the pilot valve so as to effect movement of the latter toward neutral and closing position; a compression spring engaging at one end the pilot valve at the side thereof opposite the piston face and engaging at the other end an abutment and arranged to oppose movement of the pilot valve effected by the governing fluid; follow-up mechanism including a lever connecting the main valve and the abutment, and a fulcrum element therefor; and means for moving the fulcrum element along the lever and providing for increase in the ratio of movement of the main valve with respect to movement of the pilot valve as the fulcrum element approaches the spring abutment.

16. In prime, mover apparatus of the type utilizing high temperature elastic fluid as a motivating force, the combination of a valve body formed of caststeel, a valve within the body having a stem portion extending exteriorly thereof; a relay mechanism connected to the valve stem for operating the valve and including a casing structure of cast iron, and means connecting the cast steel valve bodyand cast iron relay casing ture.

17. Apparatus according to claim 16 wherein the steel rods are tapped into the cast iron relay casing.

18. In operating mechanism for the motive fluid admission valve of a prime mover, the combination of an operating piston comiected to the admission valve, pilot valve means for controlling the application of fluid pressure to the operating piston, means responsive to movement of the operating piston for restoring the pilot valve means toneutral position in order to terminate movement of the operating piston, an operating member for moving said pilot valve means and having an extent of movement such that said admission valve maybe completely closed at any speed of the prime mover, and means for increasing the ratio of movement of said operating member to movement of said operating piston as said operating member approaches the position in which it effects complete closing of the admission valve.

HENRY F. SCHMIDT.