US2395973A - Pressure control apparatus - Google Patents

Description

' March 5, 1946. v R. R. McINTOSH PRESSURE CONTROL APPARATUS Filed April 30, 1942 4 Sheets-Sheet 1) lNVENTOR Robert'R BY 02 .g lntosh M oRNEY Man-db 5, 1946. R. R. MclNTOSH PRESSURE CONTROL APPARATUS Filed April 30, 1942 Sheets-Sheet 2 INVENTOR 'RMCIRCOSR 365% (PM I March- 5 1946.

i R. R. M INTOSH PRESSURE CONTROL'APPARATUS Filed April 50, "1942 4 Sheets-Sheet s- A ORNEY INVENTOR "RobertRMcIntosh 1 Mgrch 5, 1946.

R. R. McINTOSH PRESSURE CONTROL APPARATUS- Filed April 50 1942 4 Sheets- Shee t 4' INVENTOR R0 ertR McIntbsh BY motive smoke box as well Patented Mar. 5, 1946 UNITED STATES PATENT OFFICE 2,395,973 7 i I PRESSURE ooNTRoL APPARATUS Robert R. McIntosh, Battle Creek, Mich. v Application April so, 194.2,Serial No. 441,095 1 (c1. sc 90) 18 Claims.

. The present invention relates broadly to pressure control apparatus, and in its specific phases to apparatus for volume-velocity control of the flow ;of exhaust steam from fixed area exhaust orifice, suction inducing, nozzles in steam locomotive front ends to govern among other things, the back pressure of said exhaust steam..

The present-day steam driven railroad locomotives are provided with an exhaust stand in the smoke box at the front end thereof. Steam exhausted from the locomotive cylinders is passed through this exhaust stand and the fixed area nozzle mounted thereon and directed out of the smoke stack to create suction pressure in .the smoke box and draft through the locomotive to promote combustion in the fire box. The exhausting of a small amount of steam in this man-v er through an exhaust stand having, according to common practice, a fixed outlet area of approximately one-twelfth'the area of one of the locomotive cylinders, such as is standard practice with an existing 4-8-4 type Grand Trunk Western U-3-a locomotive, produces little suction pressure in the smoke box, while the exhaust of a large amount of steam under the same conditions produces extreme suction pres sures and high back pressures on the locomotive cylinders. These high back pressures adversely affect thepower output of the locomotive due to their reduction of the mean effective pressure on the piston in each of the cylinders. Abnormally high draft created in this manner, if applied directly to the fire bed in the fire box, would tear same and not only adversely affect combustion efficiency but promote. serious discharge of burning coaland cinders from the locomotive with attendant abnormal scouring effect on the tubes, superheater units, and other parts in the path of fiow of the products of combustion. To reduce this condition it is standard tions, in turn, result in undesirable smoke emission and require the use of live steam from a blower ring, normally mounted on the top of the exhaust stand, to maintain sufiicient draft for minimum operation requirements.

A few attempts have been made to solve these difliculties, but such attempts have failed to recognize that the problem involved is a matter of volume-velocity control of the flow of exhaust steam from a fixed area orifice and that the solution of such, in turn, should be based on a careful consideration of the speed, output, and cutoif settings for anygiven class of locomotive unthat a smaller fixed area orifice should be used practice to install 'ballles and netting in the 1ocoas to employ restrictive arches in the fire box and reduced size openings in the grates. I

volved thus recognized that the draft must be held down at its upperlevels and took care of same in a limited way by means of the choking elfect of the bafiles, et cetera. That procedure, however, resultsin highly variable and generally unsatisfactory Lcombustion conditions, does. not

reduce the detrimental effect of high back pressures, and moreover it increasesthe amount of exhaust steam which mustbe passed through the exhaust stand in a given unit of time to meet the minimum draft requirements. Those condi- Those familiar with the art'inder consideration. Where been attempted by bypassing part of the exhaust steam, there has been no recognition by the art at the top of the exhaust stand, nor that by such procedure a relatively small amount of exhaust steam would meet the requirements for creating minimum draft, thus making a better operating and more eflicient construction. The apparatus which has been devised for varying the normalexhaust of steam through the smoke stack has been ordinarily referred to as draft control apparatus, while in reality it is a form of back pressure control apparatus wherein draft control is incidental. The apparatus of my present invention deals in its specific phases with back pressure control of steam exhausted from locomotive cylinders, at least a part ofwhioh is directedup the'locomotive smoke stack for the creation of suction 'pressure'in the locomotive smoke box. This back pressure control apparatus cooperates with a true draft control apparatus such as I have described in my copending patent applications, Ser. No. 381,290, filed March 1, 1941, now Patent No. 2,379,916, and Ser. No. 428,262 filed January 26, 1942, now Patent No. 2,377,895, to produce a highly efllcient operating combination. A study of the shortcomings, difiiculties, and misconceptions of the prior art led to the discovery and developinvention is the provision of an apparatus for automatically controlling the back pressure on the locomotive -cylinders while producing sufficient back pressure to obtain the minimum draft required for combustion purposes with a relatively smaller amount of exhaust steam.

Another object is to provide an apparatus for holding the back pressure under substantially all locomotive operation conditions above the amount required for creating adequate draft for combuscontrol of draft has tion purposes and yet at the same time holding this back pressure moderately close to the minimum amount required for adequate draft under varying conditions.

Another object of the present invention is to provide an exhaust steam expansion space'between the outlet from the cylinders and the fixed area exhaust orifice at the top of the exhaust stand, so as to reduce the extreme pulsations of exhaust from the cylinders and cause same .to assume a more uniform ,flow.

A further object is to provide aback pressure control mechanism utilizing gravity held valves for controlling exhaust steam back pressure and by-passing part of the exhaust steam whenever said back pressure tends to .rise above the level for which said valves are set to open.

A further object is to provide an apparatus of the character described wherein the gravity held back pressure control valves are freely movable and float on a cushion-of :exhaust steam as same flows thereunder under normal operating conditions.

A further object is to provide an apparatus wherein the exhaust stand nozzle :isof reduced size so as to produce the minimum required suction pressure in the :smoke box with a relatively smaller flow of exhaust steam, said reduced size exhaust stand nozzle being supplemented with suitable valvesto handle aportion of the exhaust from the locomotive :cylinders .and maintain .reduced back pressure :on same.

..A :further objecttis to .provide :an'exhaust stand assembly utilizing therein not only .a reduced size exhaust anozzle, but also an expansion space, and a chamber or chambers having suitable valves therein for controlling the back pressure "of the exhaust .isteam flowing .into the assembly from the locomotive cylinders.

nsnu further object is to provide a pressure controlling apparatus which is very flexible in :nperation and adapted for a wide range of use. A still further object is to provide an auxiliary nompartment or compartments, preferably in- :cluding suitable valves therein to meet special back pressure requirements, and if desired the auxiliary compartment .or compartments may be built into't'he exhaust stand itself.

A still further object is to provide means in connection with an auxiliary compartment or compartments for automatically controlling the operation of same under special conditions.

' Still' further objects and advantages "of the present invention will appear as the description proceeds.

To the accomplishment of the foregoing and related ends, the invention, them-consists of the means hereinafter fully described and particularly spointed i out in the claims, the annexed drawings and the following description setting forth lin "detail-certainmeans for carrying out the invention, such disclosed-means illustrating, however, but several of various ways in which the principle of the invention may-be used;

In. said annexed drawings:

Figure 1 illustrates a' locomotive front end in side. elevation with part of the shell of same broken aw-ayito show an assembly'of 'one form of theipres'ent invention.

Figure .2 :is a front elevational view ta'ken along line 2-2 of Figure 1, looking in the direction ofthe arrows. a ,Figure ,3 is 'a partially sectioned andenlarged elevational view takenalong line i3-#3-o'fli igure l,

lookingxinithri direction of the arrows.

Figure 4 is a partially sectioned elevational view with the valve members shown elevated for clarity, said view being taken along line 4-4 of Figure 3, looking in the direction of the arrows.

5 Figure 5 illustrates a side elevational view of a modified form of apparatus embodying the present invention.

Figure 6 illustrates a partially sectioned view taken along line 6-6 of Figure 5, looking in the direction of the-arrows, all but two -of the valve members being .omitted, i and they 'shown slightly elevated for clarity of understanding.

Figure '7 illustrates a section view taken along line 1-1 of Figure 6, looking in the direction of the arrows.

Figure -8 illustrates a locomotive front end in side elevation with part of the shell broken away to show the assembly of a preferred apparatus embodying the present invention.

"Figures illustrates a top view of a modified construction exhaust stand as viewed :in the direction of "the arrows ll- 9 ef-Figure i8.

iFigure .loiillustrates a frontelevational view "of theessembly shown in .Figure -8, looking in the direction of the .arrows'ilfllfl thereof, anddi- .agrammatically illustrating on enlarged scale a control mechanism for use with-same.

:Figure 11 illustrates .a partially sectioned elevational view taken along line l t-H of Figure 9, .lookingin the direction of the arorws.

Figure 12 shows an enlarged and partially sec ti'oned side elevational view of a preferred form of valve guide sleeve usable "in the assembly illustrated in Figure 11.

The controlling of back pressure in a railroad locomotive, or the like, involves several factors. In the first place, the back pressure-on the locomotive driving cylinders should be maintained as low as possible since the lower the back pressure is maintained, the higher is the mean effective pressure on the driving cylinders with correspondingly increased horsepower output for a given-quantity of steam consumed, other factors remaining constant. The volume and velocity of the steam exhausted through a fixed size orifice at the-top of the exhaust stand, according to present-day standard practice, varies almost "directly-with-the back pressure of theexhaust steam on the locomotive cylinders. Accordingly, the -suction pressure in the locomotive smoke box, *due to the disc'hargeof this "exhaust steam out of the smoke stack, increases substantially in step with the increase offback pressure. The steam demand of the locomotive which causesthisvariation in back pressure also varies the rate at which fuel must be consumed in the. locomotive fire box to maintain the required steam generation.- Efiic'ientburningof this fuel at'the same time requires the draft to be correspondingly varied. In other words, where a high rate of fuel consumption is required, a "higher draft is necessary and this in turn requires a sufficiently higher back pressure "to create that draft. So far as back pressure isrconcerned, there are thus two problems involved, first, that of holding the back pressure at the lowest possible point so as toincrease the horsepower output'of -the cylinders for a given steamconsumption, and second, the necessity of maintaining the-backpressure sufficiently high to provide for adequate draft 'requirements. "I-o meet these two problems it thus becomes necessary, for efiic'ient operation, to maintain "the back pressure at a point normally just above that which willtake care of the minimum draft requirements under various operating draft'corlcerns the pulsating exhaust from conditions. Another problem in connection able point between the exhaust outlet of the cylinders and the outlet from the top of exhaust stand 1. l The upper portion ofv each valve assembly 9 is provided with a tubular outlet memmotive or the normal uncontrolled rise of the back pressure of the steam exhausted from the locomotive cylinders, since these factors, for "instance, maybevaried by varying systems and methods of operation practiced by different locomotive engineers as well as special requirements of operation at different points on the railroad line. To'take care of this'contingency, auxiliary supplemental parts may'be used to raise, lower, or hold a particular draft pressure when those conditions arise. This againm'akes possible further increased efiiciency of operation, andis one phase of the present invention 'Referring more particularly to Figures 1, 2, 3, and 4,'of the drawings, the locomotive I has a smoke box 2 atl the front end thereof'with a conventional door 3 for access thereinto. Extending outJ-of the top of the smoke box is a smokestack 4 with 'a downwardly depending extension 5 normally having an outwardly flared bottom 6. The exhaust from the cylinders (not shown) is directed into the bottomofthe exhaust stand I which is preferably provided at its upper end with a removable fixed area exhaust nozzle and spreader bridge (not shown), or the equivalent, which spreads the exhaust steam and makes same forcibly contact the inner walls of smoke stack 4, or depending extension 5 thereof, to form a seal and thus create a partial vacuum in the smoke box which in turn induces draft through the locomotive; An expansion chamber 8 is shown attached to exhaust stand I so as to permit the pulsating exhaust from the locomotive cylinders (not shown) to expand'therein and thus make the exhaust steam delivered to the smoke stack take on a more smooth and less pronounced pulsating fiow. This, in turn, makes the draft more uniform and substantially even through the'locomotive and thus reduces the common tearing eifectlof excess pulsating draft upon the fire bed int-he locomotive fire box (not shown).

Where all or at least substantially all of the.

exhaust steam which is not to be used for water preheating, or the like, is directed up the smoke stack, according to standard practice, it creates abnormal draft suction pressures under conditions of high steam consumption, a thing which at the present time necessitates the use of bailles,

restrictive arches, et cetera, in order to hold-the suction pressure created in the smoke box'from getting so 'far'beyond combustion requirements as-to carry large pieces of burning coal from the fire bed and through the boiler'tubes with the wearincident thereto, as well as'danger of startber l I which for convenience may terminate in a discharge member lZwith outlet outside of the smoke box. Where two or-morevalve assemblies areutilized, the tubular outlet members from each valve assembly may terminate in a com-' mon discharge member if desired. For ease of assembly and disassembly of the apparatus, ground joint couplings l3 and It may be utilized.

Referring more particularly to Figures 3 and 4, the valve assembly 9 may be provided with a horizontal partition l5 which for convenience may be placed substantially at the middle thereof. Mounted in partition I5 is a valve seat or seats l6 which may be fastened in place in conventional manner. The upper face of theseseats is preferably hardened and ground to former suitable'sealing seat for the corresponding end of Valve members [1. Valve guide sleeves l8 are mounted in substantially fluid tight,manner in the upper portion of valve assembly 9 so that ing'fires with the discharged burning particles.

In order to overcome this situation, a back pressure control system is utilized, one form of which is shown in Figures 1, 2,43, and 4. This back pressure control system utilizes one or more back pressure valve assemblies 9, the bottom- 0f each of which is connected by means oftubular' member l0 toexhaust stand 1, or at some other suitvalve members I! will be guidedin an up and down movement to and from valve seats It. For

ease of insertion and renewal of valve member H, as well as valve seats [6, the upper end of valve guide members l8 may be threaded and closed by means of suitable plugs I9. Valve members I! are preferably made solid with the lower end of ground for engaging and seal-' each hardened and ing on valve seats l6. The use of solid valve members I1 permits them to operate on the gravity principle and does away with any need of using valve springs for holding the valves on their seats at pressures below which they are set to open. The use 'of valves of this type also presents the advantage of floating action cushioned by the bypassed exhaust steam undernormal flow thereof, ,while the mass of each valve member retards vibration incident to exhaust pulsations.

The use of aback pressure controlling system a such as is shown in Figure 2 permits the fixed orifice area at the top of exhaust stand ,1 to be reduced in size so that a smaller quantity of exhaust steam will create the minimum draft suction required to take care of an adequate air supply for eificient combustion in the fire box (not shown). This also presents the further advantage of eliminating the need of deliverin live steam up the smoke stack from a conventional blower ring (not shown) under light operating conditions until what is known as drifting operas tion is almost reached. This in turn, results in a considerable savingof live steam which would be required for creation of draft under operating conditions over a considerable range of locomotive operation according to-standard practice.

It is well recognized that there is an optimum amount of suction pressure draft required for each rate of combustion of fuel in the locomotive rate of combustion is necessary. With this in mind, the back pressure controlling valve. assemblies. may be set to by-pass part of the exhaust steam when the minimnum draft required .for

efficient combustion purposes has been reached,

and substantially maintain the back pressure and draft at that point until a higher rate of combustion is required. Under conditions involvin higher rates of steam consumption, the amount of steam exhausted from the driving. cylinders motive operation.

sulficient to only hold that will increase and the "amount aotfuel to be burned will require increased draft. This can also be taken care of in various'ways :by the :valve assemblies described. :For instance, if a :back pressure of five pounds per :square inch -gage is all that is required to take care of producing the minimum required rdraft over a moderate :range of operation, then valve members "mayibe made of ;a suitable weight to start elevating :for bypassing of. some exhaust steam when that pressure isrreaehed. The fixed area of the exhaust stand nozzle under these conditions should .be such as tolkeep the back pressure approximately at five pounds per square inch gag-e even under light operating conditions, thereby providing a substantially constant exhaust steam cushion for the valves. As the amount of steam consumed increases, the back pressure will tend'to increase, andthat in turn will elevate valve members l1 iurther and further until their maximum capacity for releasing steam approximatelyat that pressure is reached, whereupon the back pressure and draft will gradually increase at a more rapid rate. By determining the maximum draft and back pressure necessary under maximum combustion requirements, the proper size and number of valves with adequate size connections can be provided to readily control the draft and prevent same from rising considerably above the maximum required at any given timeor phase of loco Operationin this manner thus produces the minimum draft required under minimumoperating conditions andprevents excessive draft under maximum operating condition vThe weight of the valves to be used may be closely approximated by multiplying the areaof the valve opening in square inches by the pressure in pounds per square inch at the level which they are to maintain.

A second procedure which may be followedis to determine the back pressure required for maximum combustion requirements and then utilize valve members of sufficient weight and capacity which will hold these valve members on their seats until this back pressure is reached and will then hold the back pressure substantially at this maximum level. Where the baffles and netting in the locomotive smoke box have been removed and the restrictions in the fire boxare not excessive, a variation of two or three pounds per-square inch gage in back pressure isall that is necessary to handle the variation between normal minimum and maximum draft requirements. Accordingly, adjusting the valve assemblies to the maximum back pressure required for maximum combustion provides one way for improving the combustion efficiency and increasing the mean effective pressure and horsepower output under standard present-day conditions for the conventional railroad locomotive.

A still further improvement over the procedure ust described consists in utilizing what may .be termed the two step back pressure plan. Under these conditions the back pressures for minimum and maximum draft requirements are determined and then part of the valve members 11 setto open at a back pressure a little above that necessary for the minimumrequirements, while the remaining valve members I! may beset to open at 'a back pressure a little above the .maximum required for maximum draft conditions. The capacity :of the valve :members set for "the minimum draft requirements preferably should be minimum back :pressure until the draft required is about to exceed manage-vs that permitted by the "minimum back pressure. This allows the back pressure .to start building up at that point to take care of the increased 'draftrrequirements' until the back pressure builds up to the :maximum 'at which theremaining valve members areset to open. Under these conditions, the latter valve members should have a capacity sufiicient to control :the back pressure and prevent same from substantially rising above the maximum predetermined back {pressure required for-maximumdra'ft purposes.

:Armodification of :the 'last described procedure involves the utilization of more than two back pressure levels. :For instance, if we assume that the minimum back pressure required is 5 pounds per square inch ggage and the maximum back pressure 7 pounds per square inch gage, and that eight valve members." are 'sufiicient to control the back pressure :and prevent same .from substantially rising above the predetermined maximum back pressure. Then, for instance, two of the valve members 11 can'be set to start opening when the backvpressure slightly exceeds that required for producing the minimum draft requirements. The next :two valves can be setto start opening at a higher back pressure, for instance, 5 pounds per square inch gage, the next two valves to open at a back pressure of 6 /4 pounds per square inch gage, and thelast two valves to open at 7 pounds per square inch gage. It is thus obvious that one, two, or threelevels, but ratherone or a plurality of levels can be utilized,;and in the latter case the levels are preferably chosen so as to give step control of'the back pressure and maintain same at all times just above the minimum required for draft purposes for normal conditions of operation where the back pressure tends to rise with the combustion requirements, although not necessarily directlyin proportion thereto. Operation in this manner thus improves combustion efficiency and increases the mean efiective pressure'on the driving cyiindersas well as the draw bar horsepower under normal operating conditions, other factors remaining'cohstant.

A modified form of the apparatus-embodying the present invention is shown in Figures 5, 6, and 7.. Here the expansion chamber 8a ispreferably made a little larger thanexpansionchamber 8 of Figure 2, and the central portion 20 of same is preferably made still larger and provided with a horizontal flange 21 on the upper side of same. Back pressure valve assembly 9a isprovided with flange 22 for joining same in conventional manner to flange 21 for flow of steam into and through valve assembly 9a under operating conditions where the latter is-controlling the back pressure in the exhaust stand. Referring more particularly to Figure 6, the valve assembly 9a is provided with e horizontal partition [5a in which are mounted, atsuitablelocations, a plurality of valverseats Ifia. .Preferab-ly mounted above partition--l5a .is apair of guide members or partitions 22 and 23 whicnare provided with aligned openings 24 and .2 5 for suitably guiding valve members 11a in their up and down movement under *normal operating conditions. Partitions 22 and 2-3 are provided with suitable openings 26 and -21 which are preferably aligned and of sufficient size to facilitate :fiowef by-passed steam up through valve assembly 9a and out of same through tubular outlet member 1| la toa suitable outlet (not shown) outside of the locomotive smoke box. Housing 28 of valve assembly 9a may, bezprovided with airemovable cover member the invention is not limited to i .62, for ready access to, valve; members 11a, al:

though normally the mounting. of, plugs l9a of suitable size above: eachof thevalvemembers l'la will take care of this requirement. The setting of the valve opening level or levels, aswell as the operation or this valverassembly, may be taken care of in substantially the same manner as has been described above;in.c'onnection with valve assembly 9. I i T f A preferredtembodiment of the-presentinvention involves the provisionrof an exhaust stand which has an expansion. chamberiaswell as back pressure control valves and outlet connections built therein'tdtOne such construction is itypicallyillustrated in Figures 8,19, 10; and 11. Referring more particularlyfto Figure 11, the exhaust stand lb-is provided at its upper end with a predetermined 'fixedlarea' exhaust nozzleand a spreader bridge member 29, and a blower ring v3|]. The upper portion of the exhaust stand assembly ismade sufliciently large to provide a chamber 31,.

the inner wall 32'of which, together with the inner wall of .auxiliary chamber 39, forms the normal passageway for exhaust of steam flowing'out of the exhaust stand through the restricted fixed area orifice of; the. nozzle and-spreader bridge 28 and out through smoke stack 4. The bottom of chamber 31Lis preferablyiin a horizontal plane and provided with valve seat members l6b of suitable size and location.- Cooperating with these valve seat members for. sealing the opening through'each' of same are suitable'valve-members 11b; Valve guidesleevesl 8a are utilized forguiding valve members l'lbdnxtheir up and down mov'ementunder conditions of operation. A suitable small clearance between valvemember l'lb and-sleeve 581i is'. provided; and the surface of same in the'slid-ing area-lubricated by means of oil carried by the exhaust steam. Valveiseat members "18b may be=fastenedin place in conventional manner by threading, welding; inter connecting. of seats, orthe like, but 'in preferred -construction,th'e valvezguide sleeves (Figures 11 and 12) are preferably made long enough to contact the upper and outer edge of valveseat mem bers |6b so that when plugs |9b are tightened 1y described in' connection with c ose to: t ez ower e d. o a nd e te in in ward to a point above the maximum upper travelgof valvemember llb under normal operating conditions is preferably cut away with. the exception of azfewupwardly extending narrow ribs 35.; Thispermits ready escape ofsteam flowing from expansion chamber 81 through valveseat member Hib into chamberfll under normal'operating conditions. The upperportion; of valve guidesleeves; la is, also preferably cut away ex.-

cept for a few-narrow ribs 36, a thing whichnot I only reduces the area in contact with valve mem bers I'Ib but facilitates lubrication and freemovement of valve members] 11) in an up. and down direction under 7 normal .:operating conditions. Valve members I11) and valve seats [6b cooperat-, ing therewith may be arranged for operation in various ways, three of which have .been previous,- I the; apparatus shown in section inFigure 4. c l

Chamber 3| may extend completely around the upper-portion of exhaust stand lb if; desired,-and that construction forms one aspectof the present invention, It may be,- however, thatit is desirable to utilize a supplementary control to take care of1some special condition, several of which will be hereinafter-described; One simple way of doing this is to insert partitions; 3;' I-and;38, Figure 9) in chamber -3l 7 so asfto form-an auxiliary chamber 39. This chamberan ay; l e-supplied with one or more valve seat members lfib valve -mern bers [7b,and valveguide memberswa, or

7 previously described in connection with the valve assemblies Valve members H1) in this case would-be made of .a suitable size, weight, and quantity to take care of thespecial the like. as

condition which. they are designed ,to .han dle.

Asuitable size tubular member 140 isoonnected inconventional manner for deliveringsteam from chamber 39'when the occasionrequires; vJoined to tubular connection is a suitable-valve. M (Figure 10) :WhiCh; may bepfvarious types :of

construction, although a gate valve is normally down, they will force valve guide sleeves l8a downward so as to hold valve seats I fibfromloosening and moving out of position. Theopenings into which plugs lation of valve seat members lSb, valve guide sleeves Isa, and valvemembers' 11b, as well as the removal-of same whenever necessary. A pair of suitably large tubular outlet members I lb may 19b are threadedly fastened are preferably of suflicient size to permit the instalone of the most: satisfactory for, this, purpose. Connected to this valve is an operatingmechanism, a simple form of which mayconsist-ofan air or steam operatedcylinder 42, therpiston 43.0f which is mounted on a suitablerod ,44 connected to valve. 4| in conventional manner. so that back and forth movement of piston .43 will open and close valve 4|. j The openingof valve 4| willthus permit special "back pressurecontrol by means of the valve members in-auxiliary chamberfl q. The conventional practiceon some railroads is to have the engineer; and; particularly passenger v,train engineers, usea long, or highpercent, cut-- off for steam admission to the driving cylinders as thetrain pulls out of the station, and maintain this cut-01f withoutreduction :until, the train is manner. Directly below chamber 3| is an exj pansion chamber '81) which opens directly into the passageway lengthwiseof the exhauststand. This expansion chamber for purposes of rigidity, and sidewise guiding of exhaust steam to the inlet end of valve seatmembers I61), is preferably provided with a plurality of longitudinal vertical ribs 33. Where valve guide sleeves I 8a are used to hold valve seat members [6b in place, the lower end of each of same is preferably-provided with.

an inturned flange 34 (Figure 12) adaptedtoen gage the upper and outer edge of valve seat mem ber lSb. The sides of the sleeve from a point moving at a relatively'high rateofspeed-sand then reduce the cut-off setting as the train comes up to normal traveling speed-. I Under theseconditions with the conventional front .end, the back i pres sure; builds upto. a relatively high 'point due to the high velocity of exhaust from the ,-exhaust stand even though the steam consumptionisrelatively low compared'withhigh speed-heavy oper- V ation. This high back pressure in turn will produce high draft suctionpressures and high consumption of coal when the actual steam consumption does not require heavy firing. Under those conditions, the auxiliary chamber can be used to advantage by placing therein valvermemhers 11b of a size such that they willopen under a prechosen back pressure,for instance, the min imum" back pressure at whichpart' of the valve members H19 in chamber 3'1 are set, or at some lower or intermediate back pressure below the maximum back pressure at which other of the valvemembers inthat chamber are set. The valve members 11b":- in' auxiliary chamber 39 will not? open, however; until valve 4| is opened to allow exhaust steam to flow through auxiliary chamber 39' and=tubular member- 40 to a suitable point of'discharge; The operation of valve 4| underthese'conditions may be'conveniently carri'ed" out as follows:- The-cut-off settings for the cylinders are controlled,- through a pair of reverse arms-45 and'links 46 on opposite sides of the-locomotive. Reverse arms 45" are keyed to cross shaft 41 for" operation in-unison under controi oftheen'gineer; Thus when the cut-off is tobe increased, reverse arm 45 is moved in a clockwisedirection as-viewed in Figure 10. This movement may be availed oi-for' operating'valve mi-thefollbwingmanner; A plate 48- is conventionallyfastened on-reversearm 45' and provided with an outwardly projecting arcuate flange 49 orrthe'under face ofwhich is adj'ustably mounted, in conventional manner; an. arcuate cam shoe 50, the-center" of the are being the center of shaft 41. Frame-'1 ofthedooom'otive may-be provided with a: shelf'mernber 5 2 onwhich is mounted a suitahle-valve=53 This valve is provided with a depressible member" 54 with a roller 5'5, or the like, on its'uppenend. The d'epression of depressiblemember 51 acts' to connect main air pressure li'ne 56 for air flow to line- ET for. application oi pressure-behind piston 43"of'cylinder 42; which irr-turn-actsthrough rodwto open valve 4 I; Pistom 43 is rmrmall'y held in retracted position, with valve 4| closed, under the influence" of low pres."- sure air delivered irom main air line 56- through pressure-reducing valve 58 and pipe 55. A- pressure'releasing'valve fim; set" to operate at a little higher pressure than pressure reducing valve 58, acts-terelease'pressure when-piston 43" is moved to-openvalve -41 under the influenceof the main line air" pressure. Under these conditions; it is onlynecessaryto set cam shoe 5W to depress depressible member 54 when the high percentage cut-oil?referredto is utilized. I'his inturn will cause the opening" of valve 4! and permit the valve members-in auxiliary compartment 39 to and hold the back' pressure and draft inducedtherewith atacontrolled lowerlevel-than would otherwisebe-the'case'. Valve Bil maybe closed under conditions where for some reason, the reduction of back pressure under long or high percentage cut-offoperation: and low speeds is temporarily not desired. operation. of the auxilary'chamher apparatus may also be manually controlled. For instance, valve MS may be opened and closed through theoperation of; valve 62; which would normally be placed. in the loco.- motive cah'.

Another way of takingadvantage of the auxiiliary'compartmentinvolves'theuse' ofsamewhere it is desired to carry asubstantially: uniform level back pressure under all operating condiitr chambers-31 and 39 -wouldbe setf'or the maximunr-back-'pressurerequired-to pro-duce'the max.- i'mum' draft necessary under normal operating conditions: This would give the" valve: members an excess capacity at the point where. they" are at thevergeof opening; i. e: at the balance point. Thisbalance point will normallyr'occur when the percent cut oif isrelatiVeIyy-loW; and under these conditions, the camshoe: member: would be. set

tions: fori'nstance'; allbfthe valvemembers llb v managers to cause valve'4 l to beopen: at alltimes except when-thepercent" cut-oil is low; and to allow same-to close and: remain closed under those conditions. Excessive: capacity at the". balance point tends to permit an. undesired amount of leakage through the valve assemblies: to take place, and by closing valve M this excess is reduced, a thing which also: aids in steam cushioning the remaining valves in their. operation when they arealmostin'. closed position... This auxiliary compartment; by suitably" controlling valve 41 can 'be'usedto increaseor reduce. capacity: at. any given. back pressure level, and can also be used: to increase vthe: maximum. capacity at theupper pressure level: to provident substanti'ally' positive upper back: pressure: limit. The use and: operation ofv the. auxiliary chamberis thus very flexible: and: readily: adapted: to. handle varying requirements of auxiliary" pressure; con;- trol; While only oneaux-iliary chamber: has been shown, itis to; be understood that the invention is not. limited to. thezuse' of; only one. such chamher, but rather. that onev ormorea may he: used and. that the showing: isto be. construed: as diagrammatically illustrating'same;

AZ locomotiveof the 484;Northern1type.which, inwOrking order; weighsa'666,500 pounds; operates ontwo hundred and fifty'pounds per square inch boiler pressure, andzwhichhas. 60200 pounds tractiveefiort, has'b'een equipped with this invention. This" locomotive; whiclr. is: used irrv regular and continuous" high speed manifest freight service, is giving very much" improved: performance in increaseddraw bar horsepower; greater fuel economy, moreiunifornr and-smooth operation, higher speed capability; et:cetera-;. The-fixed outlet orificearea of the exhaustrstand is 34 squareinches as compared with the 40' to "42 square: inches normally; used on" this locomotive. This reduction required. for: combustion; purposes, with a: much smaller: amount ofiexhaustrsteanr discharged per unit? ofztimer. An expansiona chamber; isutilized between thev exhaust? outlet; from: the cylinders and: the? fixed area outletr from the --exhausti stand to provide a: more:smooth1 and; uniform: flow of exhaust: steam.v Connected to; this expansion chamber is a back. pressure:valve assembly in which. are" nine twoinch diameter: valves of a sizeand weight-which?startopening; at flvepounds per" square: inch baclepressure; and three two inch. diameter valves of; amsizee and weight which start opening at six' pounds per square inch back pressure; These valves; hold the back pressure inthezex-haust stand passageway substantially in the rangerof-from five to; seven pounds per'square inch for; normal. operation ofthe. locomotive, a rangezwhich is amplefon creating the draft necessary'for" combustion purposes: Sincethis apparat'us: is primarily aback pressure controlling apparatus and incidentally a; draft! controlling apparatus; thelocomotivemas also equipped with a; cooperating truadraftcontrolling, apparatus, of the general; type,- described inamy aforementioned copending; patent. applications, to; hold. thev draft suction.- pressuresi-at approximatehr the. levels of 55",;51/2", 011-65 oiwater depending upon the varying.- requirements for eflicient operation of the locomotive: facilitate inspection of, the ironttubesheet andlsuperheatenunit, as well as improved andamore uniform, drafting of the locomotive inaccordance. with. emcient, combustion requirements meeting 3118251363111 demand, the

baffies and; netting, in. the smoke box were. also removed, Thefi-rebricl: arch.in- .the.-.fire box was arch which had been used wh cles and combinations herein also made approximatelyone half the size of the en the locomotive had the conventional-front end, a thing cooperating with-and facilitating the moreeuniform and better drafting obtained through use of my improved backpressure and draft control-apparatusr The locomotive as thus equipped isexceptionally satisfactory from the standpoint of improved operation, increased power and fuel econ"- omy, reduction of cinder cutting of the boiler tubes, superheater unit, and front end,-'substan tially balance draft from the flre box to the front end of the locomotive, and the substantial elimination of discharge of sparks from the smoke stack; Other modes of applying the principle of my invention may be employed instead of those explained, change beingmade as regards the artithe means stated by any-of the following claims orjthe equivalent of such stated means he employed. v I therefore particularly point'out and distinctly claim as my. invention: v

1. A pressure control apparatus of the character described, which comprises a means with a passageway open at one end for flow of a gaseous fluid therethrough, a flow restricting mean'ssub stantially at the open end of said passageway, a chamber, an outlet means for said chamber, said outlet means cooperatingwith said passageway and flow restricting means to create a suction I pressure in said chamber upon forceful delivery of a gaseous fluid through said passageway, 'a pressure relief means, means for connecting said pressure relief means to the passageway 'of' said first. named means ahead of said flow restricting means for controlled by-pass flow of gaseous fluid to said pressure relief means,-and a plurality of gravity controlled :valves insaid pressure relief means, said gravity controlled valves'being adapted to elevate and permit the by-passingof gaseous fluid through said pressure relief means when the pressure of said gaseous fluid in said pas-' sageway exceeds the predetermined amount.

2; A pressure control apparatus of the char acter described,'which comprises a means with a passageway open at one end for flow of a gaseous fluid therethrough, a flow restricting means substantially at theopenend of said passageway, a chamber, an outlet means for said chamber, said outlet means cooperating with said passageway and flow restricting means to createa suction pressure in said chamber upon forceful deliveryof agaseous fluid through said passageway, .a pressure relief means, means for connecting said pressure relief means to the passageway of 'said-firstnamed means ahead of said flow restricting means for controlled bypass flow of gaseous fluid to saidpressurerrelief means, a plurality'of gravity controlled valves in said pressure relief means a valve seat for each valve, a valve guide cage for guiding said gravity valves in their movement, and means for forcing each of said valve guide cages against one of said valve seats tohold same in place, said gravity controlled valves being adapted to elevate and permit the by-ipassing of gaseous fluid through said pressure relief means when the pressure of said gaseous fluid insaid passageway exceeds the predetermined amount.

3.A pressure controllingapparatus, which comprises a means with open passageway for flow of a gaseous fluid therethrough, a flow re-' stricting means substantially at the outlet end disclosed, provided of =saidpassageway, an expansion means for gaseous fiuid,'said expansion means being con nected to andopening into said passageway at a point between the inlet thereto and said flow the predetermined amount at which restricting means at: the outlet therefrom, a

pressure relief means, said pressure relief means being connected to the passagewayof said first named means ahead of said flow restricting means for controlled by-pass flow of gaseous fluid from said first named means through said pressure relief means, and valves in said pressure relief means, said valves being adapted to open for flow of said gaseou fluid through said pressure relief means when the pressure of said gaseous fluid in 'said passageway exceeds said valve means has been set to start opening.

4 A pressure controlling apparatus, which comprises'a means with 'openpassageway for flow of a gaseous fluid 'therethrough,' agflow restricting means substantially at the outlet end of said passageway, an expansion means for gaseousfluid, said expansion means being con nected to and opening into said passageway at'a point subsequent to the point of inlet of said gaseous fluid into said passageway, and ahead of said flow restricting-means; a' pressure relief means, said pressure relief means being connected to'the passageway of said first named means ahead of said flow restricting means for controlled bypass flow of gaseous fluid from said first named means through said pressure relief means, and valvemean's forming part of said pressure relief. means, said Valve, means including vertically mounted gravity held ,valves and cooperating substantially horizontal, valve seats below same, at least part of thevalves of said valve'means being adapted to elevate and float on'the gaseousfluid flowing into and through said pressure relief means when the pressure of said gaseous fluid in said passageway exceeds the predetermined amount at which the weight of said valves has beenset to deterrestricting means, and a pressure controlled auxiliary :outlet from, said expansion means, whereby the pulsating flow of gaseous fluid is .more smooth and uniform as it passes through said flow restricting means in said passageway. 6. In an apparatus of the character described for. handling'a'pulsating flow of gaseous fluid, the. combinationwhich comprises a means with open passageway' forzflow of a gaseous fluid therethrough, a flow restricting means for said passageway, an immovable expansion means for pulsating jgaseous fluid flowing through said passageway, said expansion means being connected to saidxpassageway ahead of said flow restricting means, and a pressure controlled auxiliary outlet from said expansion means, rib members in said expansion means for guiding theflow of'gaseous fluid therein, whereby the pulsating flow of gaseous fluid is more smooth and uniform as it passes through saidflowrestricting means in said passageway. I

7. In a by-pass type of pressure controlling blies,

mg with said valve seats; to form an operable valve. assembly, skeleton: valve cagemeans for guiding said valve members. for movement to andrfrom the valve; seats; in. a direction. sub.- stantially'vertical to said. horizontal panehmeans for forcing. saidv valve cases. against. thetop of said valve: seats to hold. samefirmly in place, and an. outlet: means connected: to: said chamber above; said panel, said valve members being. of a: suitable weight to elevate and thereby open said valve for' by-passing aportion.- of said highly fluid body through. said chamber: and said outlet when the pressure of. said highly fluid. body in said: first named means exceeds av predetermined amount;

8; An apparatus for: use in connection with a steam driven railroadi locomotive, which comprises athousing, asub'stantially horizontal panel for said housing, said panel. having; a plurality of" openings: therethrough, valve; seats: in said openings, gravity control type. valve members above said: panel and cooperating withsaid valve seats to form a plurality of operable valve assemmeans for guiding: said valve. members for movement to and from said valve seats in a direction substantially vertical to said horizontal panel, an outlet means connectedto said housing above'said panel, and means for'delivering to the inlet of said valves at least part of thesteam exhausted' after-use for driving said locomotive, said valve members being of asuitable weightto automatically elevate and thereby open said valves for bypassingexhaust steamlthroughzsaid housing and out of said outletiwhen the exhaust steam pressure exceeds a predetermined amount.v

9'. In a railroad locomotive having steam operated driving cylinders, the combination of an exhaust standhaving a passageway through which a major portion of the exhaust steam from said cylinders is normally passed, a flow restricting means substantially at the'outlet end of said exhaust stand, a pressure relief means connected to said passageway through the exhaust stand, said pressure relief means being adapted to bypass part of the exhaust steam flowing through said passageway when the pressure thereof exceeds a predetermined amount, an auxiliary pres; sure relief apparatus connected in parallelto said first named pressure relief apparatus, and means for controlling the time at which said auxiliary pressure relief apparatus becomes operative, whereby the effect of said first named. pressure relief" means upon the pressure of the exhaust steam flowing through said exhauststand is=var-.- ied in predeterminedmanner. v

10. In a railroad locomotive-having steam operated driving cylinders, the combination of an exhaust stand having a passageway through which a major portion of the exhaust steam from said cylindersis normally passed, a flow-restricting means substantially at'the outlet endof' said exhaust stand, a pressure relief meansv connected to said passageway through the exhaust stand, said pressure reliefTm-eans; being" adapted: to bypass: part oi the exhaust steam" flowing; through said: passageway whenthe; pressure thereof ex. ceedsa predetermined amount,,anauxiliary pres;- sure relief. apparatus connectedrin parallelto-said first named. pressure relief apparatus, and means for controlling the. time at which said. auxiliary pressure relief apparatus. becomes operative; whereby the effect. of said first. named pressure relief means upon the pressure of: the exhaust steam flowing through said exhaust stand is var.- ied in predetermined'manner, said'means. for con.- trolling the time at which said auxiliary com.- partment becomes, operative comprising a: tubular outletmeans from said auxiliary: compartment, at shut-off valve for said tubular outlet means, and. a. camcontrolled assembly; for. controlling the; opening and; closing of said. shut-off valve in. accordance with predetermined settings of the valvezcuti-offq assembly for controlling the inlet; of: steam to the driving cylinders.

11. In anapparatus of the. characterrdescriioerh the combination which comprises a means with an. open passageway for flown of: gaseous fluid therethrough, a pressure relief means, meansfor connecting said pressure relief means to. the passageway of said first namedmeans, ahead of the outlet therefrom, for by-pass flow of gaseous fluid to said pressurerelief means; a multiplicity of. valves in said pressure relief means forbypassing. a portionof: said gaseous fluid when the pressure of same in said first named passageway exceeds the: pressure at which said valves are set to open, part of said valves being adapted. to open at a diiferent pressure from the others, an auxiliary pressure relief meansconnected to said passageway in parallel to said first named pressure relief means for supplemental control of the pressure in said passageway, and means controlling the time and condition under'which' said auxiliary pressure relief means is permitted to operate.

12; A steam locomotiveexhaust stand, which comprises in combination a body member having a normally open exhaust passageway therethrough, a chamberin said body member, a valve means responsive to pressure in excess'rof a predetermined amountin said passageway-for controlling the inletzfiow of exhaust: steam. from said passageway into said chamber, said: valve means being in said chamber; and meansconnected; to said chamber for discharging therefrom the ex.- haust steam flowing thereinto under control. of said valve means.

13. A steam locomotive exhaust stand, which comprises in combination a body member having a normally open passageway therethrcu'gh and an expansion means connected to the lattena-chamher in said body member, valve-means. responsive to pressure in excess of a predetermined amount in said passageway for controlling. the inlet flow of exhauststeam from said passageway: and expansion means into: said chamber, said: valve means being in. said. chamber, and" means connected to. said chamber for discharging" therefrom the exhaust 'steam flowing thereinto' under control of'saidvalvemeansl.

14. A steamlocomotive exhaust: stand, which comprises in combination: a body member-having a, normally open passageway therethrough and an expansion means connected to the" latter; a flow restricting means'at. the outlet endof said normally open passageway, said flow restricting means acting to decrease thefreeoutlet. area so as. to. increase, the. velocity: of exhaust: for a.- given volume of steam: exhausted. in a; unit of time therefrom the exhaust steam flowing thereinto' under control of said valve means.

15. A steam locomotive exhaust stand, which comprises in combination a body member having a normally open passageway therethrough, an

exhaust expansion means connected to said passageway, an exhaust nozzle and steam spreader means at the outlet end of said normally open passageway, said exhaust nozzle acting in conjunction with said steam spreader to decrease the free outlet area so as to increase the velocity of exhaust for a given volume of steam exhausted in a unit of time through said restricted outlet of said passageway while said spreader means also acts to spread the stream of exhaust steam flowing through said outlet, a chamber in said body member, valve means responsive to pressure in excess of a predetermined amount in said passagewa-y'for controlling the inlet flow of exhaust steam from said passageway and expansion means into said chamber, and means connected to said chamber for discharging therefrom the exhaust steam flowing thereinto valve means.

16. IA steam locomotive exhaust stand, which comprises in combination a body member having a normally open passageway therethrough, an exhaust nozzle, and steam spreader means at the outlet end of said open passageway, said exhaust nozzle acting in conjunction with said steam spreader to decrease the free outlet area so as to increase the velocity of exhaust for a given volume of steam exhausted in a unit of time through said restricted outlet of said passageway while said spreader means also acts to spread the stream of exhaust steam flowing through said outlet, an exhaust expansion means connected to said passageway in said body memberat a p int ahead under control of said nected to said chamber for discharging therefrom the exhaust steam flowing thereinto under control of said plurality of valve means.

17. A steam locomotive exhaust stand, which comprises in combination a body member having a normally open passageway'therethrough, an exhaust expansion means connected to said passageway, an exhaust nozzle and steam spreader means at the outlet end of said normally open passageway, said spreader means acting to both spread the stream of exhaust steam passing same and to decrease the free outlet area of said normally open passageway so as to increse the velocity of exhaust for a given volume of steam exhausted through same in a unit body member, valve means for controlling the inlet flow of exhaust steam from said passageway and expansion means into said chamber, means connected to said chamber for discharging therefrom the exhaust steam flowing thereinto under control of said valve means, an auxiliary chamber, valve means for controlling the inlet flow of exhauststeam from said passageway and expansion mean into said auxiliary chamber, and means connected to said auxiliary chamber for discharging therefrom the exhaust steam flowing thereinto under control of said valve means.v

18. A steam locomotive exhaust stand, which comprises in combination a body member having of the exhaust outlet therefrom, a chamber in said body member, a plurality of valve means in said chamber, said valve means being responsive to pressure in said passageway for admitting exhaust steam from said passageway into said chamber, part of said valve mens operating to open at one pressure and at least one valve adapted to open at a higher pressure so as to control the inlet flow of exhaust steam from said passageway and expansion means into said chamber, and means cona normally open passageway therethrough, an exhaust expansion means connected to said passageway, an exhaust nozzle and steam spreader means at the outlet end of said normally open passageway, said spreader acting to both spread the stream of exhaust steam passing same and to decrease the free outlet area of said normally open passageway so a to increase the velocit of exhaust for a given volume of steam exhausted through same in a unit of time, a chamber in said body member, valve means for controlling the inlet flow of exhaust steam from said passageway and expansion means into said chamber, means connected to said chamber for discharging therefrom the exhaust steam flowing thereinto under control of said valve means, an auxiliary chamber, valve means for controlling the inlet flow of exhaust steam from said passageway and expansion means into said auxiliary chamber, tubular means connected to said auxiliary chamber for discharging therefrom the exhaust steam fiowingthereinto under control of said valve means, separate valve means for opening and closing said tubular means connected to said auxiliary chamber, and means for controlling the operation of said last named valve means.

ROBERT R. McINTOSI-I.

of time, a chamber in said i

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