US2654382A - Control valve mechanism - Google Patents

Description

Oct. 6, 1953 llzyl c. F. BALL ETAL CONTROL VALVE MECHANISM Original Filed Feb. 26, 1947 3 Sheets-Sheet l fzrie; 115022. B262202d T17052 Oct. 6, 1953 c. F. BALL ETAL 2,654,382

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CONTROL VALVE MECHANISM Original Filed Feb. 26, 1947 s Sheets-Sheet s 6/ 22 AMJWMI Patented Oct. 6, 1953 UNITED S Pa:.,v assign'ors. to Manufactur g G n 'nyn azcorporationrofiPennsylvania Continuation of abandoned application Serial No. 81],3-74', Match- 9, 1949, whichis a divisionof' application Serial No; 731,126, February 26;- 194'7. 'Ih'iis application March-.11); 1952-, Serial:

15 Claims. (01'. 137-102) Qur invention. relates: to improvements in' con;- trolvalve-l mechanisms. Control! valve mechanisms; of the type to: which our invention relates have;particularzutilityinmihevehicles of theztyne known as: shuttle carsi but: are not confined to suchiuse.

Shuttle cars?" very, commonly have; provision for the supply of power tothein including. a: reel onwhich. a; power cable; is;wound.. Heel drive-and control means: mustv'be provided so that thereels will wind up cable; when the cars are moving towards the point of. connection, of the cable; to alsourceaofipower'and suchiasito' perm-itlthedrawingtofi: oii theecablew'hen the; carsare movingaway tromsuch. point of. connection, and also; suchithat, when. the;- carsmovez in. courses or: paths which involve: a need for a shiitingtrom a winding-in. tova payingyoutor tromia paving outxtocawinding-in, oi the cable, this: will; be automatically accomplished. It is also important. that: when: paying out ceases,;conditions shall immediately: be established in readiness fora windingeini operation, in order toprevent possibility of the cables being run over, and to prevent an accumulation of slack which might; interfere with the smooth winding oft-he cable. It is further-,- therefore; important to maintain; some. tension. on' the cable even (lur ing the time when-ritislbeing pulled 01f: of there'el.

A very desirable. apparatus for accomplishing the obj ectives mentioned is described and claimed in our application Serial: N0 731,126; filed Febru va-ry 26; 1947,, for Cable. Reeling Mechanism of which; application this present application i's a divisiom. Thisapparatus, its illu'straitive form thereishown and. described; includes a pump for supplyingahydraulicfluid; a-motor-pu-mp device which, the pump supplies fluid and is 'operatively connected. to the reel sothat when suclrmotor-pumpl device: operates as a motor it drives the: reel and so: that it is drivenb? the reel whent cable is unwound; together with means '.the improved. valve means of this present case, if the illustrative einbodimehtcontrolled'entire 1 y by hydraulicpressuresproducedin the-normal operations of the device for; imposing on the motor-pump device a substantial pressure, say, for illustration but without limitation thereto, 300 p. s. i. when the reel is being, d'rfi'venin= the winding-in direction; a pressureontheorden, but without limitation thereto, of: 100 p. s; 1. during unwinding of thecable; and apressure, againron the order, but: Without limitation! thereta. oi 30.0 p. Sri'. when the reelis,statienary,,the;latter presr sniebeing automatica ltb imposed uponthe motorr pump device. immediately after a the; reel; comes to rest after an. unwinding operation, Suchvali/ie means also permits; the freedischarge, substantially without any back pressure, of the: full volume of fluid: displaced by the pump. wliinthe reel or drum isnot being drivenbvthe. motor:- pump; device but is instead driving the latter as a-pump-andcausing the fluidithen" pumped there. by to be discharged against a back pressure: im posed upon the motor-pump; device, when. cable is'being drawn: offrthe reel That apparatus includes an; automatic valve mechanismwhich forms. the subject, matter of this divisional application, Such automaticlvalve mechanism; includes, in a preferred e bfit iinent, valves operative respectively to determine-the pressure imposed on: the motor-pump; device of such system as is referred to when the cable is being wounds in; and toidetermine thebackpness sure imposed. on-themotor-pump: device. when the cableis; being; unwound, and anautomatic shifter valve controlled: at least in part, by the pressure built upgby the motor purnpzdevice, when-thesa ne is acting as a; pump for shifting; connections, in such a manner that wheneas, during} winding in ofthe cable the; reliefr device hav ing thehigher setting is in. control, the relief. device having: the lower setting; shall become operative when cable is to be pulled ofi the reel,v andthernainpump discharge shall then be autoinaticallitrelievedof substantially all back pressure; a preierred embodiment there simian be included in the means for controlling the osition, of the shifter v,alv e. mentioned, arrangements operative to place in conrtol ofth'e' pressure in the Iin'e'between the pump and motorpump device, the pressure relie'fvalve with the liigher'setting, when the reel comes to a stop.

In more specific terms; the improved valve means may include; in a preferred embodiment thereof} a-pair oi pressure reliefi va1vessevat: ifferent pressures, at shiftervalve; an a check valve, a supply' passage; a vent passage, and a passage for connection to ad'evi'ce to be controlled by said valvemeans; the pressu'rerelief 'valve' liaving the higher-setting having itssuppl'y side 1 stantl y in free communicatihn Wit/1 1 said scrapie passage and its discharge side constantly in free communication with said vent; said-"check valve also having itssupply si'zie constantly freewamunication with said supply passage and havihg its: dischargev side; constantly in free communication with said passagesforconnection to a device 1701138, controlled; theapressurreliei? valve having the lower setting having its dischargelsidercomstantly in free communicatiom with: said vent,

and having its supply side connectible with said passage for connection to a device to be controlled under the control of said shifter valve, and said supply passage connectible with said veiit under the control of said shifter valve, the latter, at its opposite ends subjected to the pressures in said supply passage and in said passage for connection to a device to be controlled. I

When the pressure in the passage for connection to a device to be controlled by said "valve 1.

means is less than the pressure the supply passage, the shifter valve means is. adapted to interrupt communication between the former passage and the supply side of the pressure relief valve having the lower setting and between the supply and. vent passages, and upon a pressure in the passage for connection to a device to be controlled by said valve means higher than the pressure in the supply passage, said shifter valve means is adapted to connect the former passage to the supply side of the pressure relief valve having the lower setting, and to connect the supply passage to the vent passage.

An object of our invention is to provide an improved controlling valve mechanism. Another object of our invention is to provide an improved controlling valve mechanism including a plurality of selectively operative pressure relief valves and shifter valve means. A further object is to provide an improved control valve including a plurality of pressure relief valves and a shifter valve hydraulically controlled for the purpose of rendering one or the other of said relief devices effective to control the pressure in a line connectible to a device to be controlled by said valve means. Yet a further object of our invention is to provide an improved control valve mechanism including a plurality of differently set relief devices and a shifter valve constructed and arranged to render one or the other of said relief devices effective to control the pressures in a line to a device to be controlled by said valve means, and also to insure control by the relief device having the higher setting upon cessation of flow through the line connectible to a device to be controlled by said valve mechanism. Other objects and advantages of the invention will hereinafter more fully appear.

Referring to the drawings in which one illus- U trative embodiment which our invention may assume is shown:

Fig. 1 is a diagrammatic view illustrating a control system which we have chosen as a setting in which to illustrate our improved control valve mechanism.

Fig. 2 is an enlarged end view of the control valve mechanism, the view being taken from what might be called the top, if the parts shown in Fig. 2 be considered to have the same relationship in space as is indicated on the first figure of the drawings.

Fig. 3 is a view of the control valve mechanism of Fig. 2 viewed from the left hand side thereof with the mechanism in the position indicated in Fig. 1.

Fig. 4 is an enlarged view of the control valve mechanism, showing the same in the position indicated in Fig. 1.

Fig. 5 is an enlarged sectional view on the plane of the section line 55 of Fig. 4.

Fig. 6 is an enlarged sectional view on the plane of the line 6-6 of Fig. 3.

Fig. 7 is a sectional view on the same plane 4 and scale as Fig. 5, with parts shown in different relative positions.

Fig. 8 is a fragmentary section taken on the plane of the line 8--8 of Fig. 5;

Figs. 9 and 10 are views similar to Fig. 1, but showing the control valve mechanism in, as it were, developed or schematic views so that all the passages therethrough and elements thereof may be followed in their working operations.

Referring now to the drawings, and first to Figs. 1, 9 and 10, it will be observed, as a preliminary to the detailed description of the control valve mechanism which is the subject matter of this present application, that a source of hydraulic fluid is shown at I, as, for example, a suitably disposed tank, receptacle or sump, to contain the necessary quantity of hydraulic fluid. The source I is connected by a suitable suction line 2 with a main pump 3, which is driven from any suitable source of power, not shown. The pump 3 delivers fluid under pressure to a line 4 which is connected with a valve mechanism 5, which is the particular subject matter of this application. The valve mechanism 5 has a connection 6, hereinfter sometimes referred to as a conduit and as a line, with a motor-pump device I operatively connected, as by a belt 8, with a cable reel 9 upon which a power supply cable It is wound. Let it here be noted again that while our invention is specifically described with reference to a control system for a cable reel carrying an electric cable for supplying current to electric motors, the same is not in any sense limited to such systems. The motor-pump device is connected with a conduit H-a vent line-which leads back to the source I, and a relief line I3 leads from the valve mechanism 5 to the line H. The pump 3 is shown as of the intermeshing gear type, as is also the motor-pump device 1.

The valve mechanism 5 includes a supply chamber I6 to which hydraulic fluid is delivered by the conduit 4. From this chamber fluid may be delivered through a shifter valve chamber I! back to the connection 13 leading to the source I, or, as will shortly be described, to another chamber i8 which is connected with the conduit 6 leading to the device to be controlled, as illustrated to the motor-pump device 7, and the conduit 6 communicates also with the shifter valve chamber 11, as later described.

Desirably, the chambers I6 and I8 may be formed in line with each other, as shown in Figs. 5 and 7, and separated by a -ported septum 20, which forms a valve seat 2|, with which a check valve 22 is adapted to cooperate and against which said check valve is adapted normally to be maintained by a spring 23, which at one end rests against the check valve and at its other end rests upon a plug 24 with which the conduit 6 is threadedly or otherwise suitably connected. The structure of this check valve 22 may be seen from Fig. 8; and it will be noted that this valve has a number of slots 25 in its periphery through which fluid may flow from the chamber Hi to the chamber 18 when the valve 22 is unseated. The supply or upstream side of the check valve communicates freely with the supply chamber I6 and its discharge or downstream side freely with the conduit 6.

Theshifter valve receiving chamber Il includes five annular chambers, each spaced from the next adjacent chamber by a ported partition. These annular chambers, starting from the top in Fig. 5, are numbered respectively 26, 21, 28, 29 and 30. A ported partition 3| separates the chambers 26 g ate-see and "21". A ported" partition 32' separates the chambers and 26. Similarly, ported partitions 33 and 34 respectively separate the chambers 26 and 2e and the chambers 29 and 36. Each of the ported partitions has the port therethrough of the same size 'as'each of the others, and these several ports are coaxially'arranged so that their surrounding walls provide guidance for a spooltype or doublehead'edshifter valve 36- comprising an upperhollowhead 3'1 and a lower head 38, a connecting portion 3 9 of reduced cross section whose presence: resultsin the provision between the, adjacent surfaces of said heads of an annular fluid conducting groove or conduit 4-0, and a stop projection 4|. The head 31, as indicated, has a recess 42 therein into which extends a spring 43 whose upper end in Fig. 5" contacts an abutment plug-4'4 suitablypacked at 45' to prevent leakage. A passage 4610f relatively small diameter atits lower end 4-! extends from the chamber 42 through the stop portion 41 of the valve 36. The stop portion of the valve is adapted to cooperate with a suitable abutment plug 48.

The annular chamber 26 communicates with the-supply chamber l6 through a port or cored openings!) (whethera bored port or a cored opening' dependingon whether the valve casing is machined fromthe solid or cast). Similarly, the annular space 21 communicates as at 5| with the chamber l6. The annular chamber 28 communic'ates through the conduit I3 with the conduit H leading to the source I. The annular chamber' 29 communicates through a port or opening 52 with a chamber 53 in a relief valve casing 54 shown in the drawings as a separate element from themainbody of the'valveinechanism as a whole, but obviously fo'rmable with it as a unit if desired. The annular space 30 communicates an opening 55 with the chamber l8. The

annular chamber 28 also communicates through The annular chamber 26 *communicates through an opening 6| with a chamber 62 in the relief valve housing 58. The chamber 53 is separated from the chamber 60 by a ported valve seat 6'4 with which a spring pressed relief valve 65' is adapted to cooperate. A spring 66 having a follower 61' adjustably loaded by an adjusting screw and nut mechanism 68 controls the compression of the spring 6.6, and thus determines the pressure at which the valve 65 will lift from the seat 64.. The chamber 53 is at the upstream side of the valve 65, the chamber 60 at its downstream side. A valve seat 69 surrounding a port extending between the chambers 51 and 62 is adapted to. cooperate with a relief valve 1- t pressed in a closing direction by a spring 12 which rests against a follower 1-3 whose position may be adjus'ted. by suitable screw and nut mechanism 14. The chamber 62 is at the upstream side of valve TI, the chamber 51 at its downstream side. It will be noted that when the valve 36. is in toprposition, it does not prevent communication between the chamber [6 and the port 10. The normal compression of the spring 12 will be much higher than the normal compression of the spring 66 when they are controlling valves having equal areas subjected to pressures tending to unseat such valves. For example, it may require a liquid pressure of 300 p. s. i. in chamber 62 to unseat valve H while, for example, a pressure of 1,00

p. s. i. in chamber 53 will suflice to unseat'valve 65.

The pump 6 maybe-considered, for the purpose of describing the mode of operation of-the embodiment of our invention which has 'beene'xplained above, to be driven continuously while the vehicle is in use; Accordingly, it is takingin liquid from thesource t through the conduit 2 and discharging it through the-conduit Mute-the chamber f6, and the numso delivered to the chamber 66' must go some'where. Obviously, from what has beensaid, the fluid when conditions-are such that the cable can be wound in,'may= at least in part go-past the check valve 22 and through the conduit 6 and into thamotor-pumpdevice-1' and drive the latter in "a direction tociiec't winding-i-n of the cable 16, and then pass back-to the source 1 throughthe conduit H. Because the rate of winding-inof the cable'will be controlled by the rate at which the vehicle moves in the direction in which the cableextends, it will be evident that all oftheliquid pumpedby thepump 3' cannot pass through the: motor pumpadevice; 1?, underordinary circumstances, atv least, and ac, cordingly prov-isionis made for the return of the excess liquid discharged by the pump 3 to the line H through the connection [3. As'considerable power must beexerted by the motonpump device 1 to effect winding-in of the cable: at; the desired maximum. rate, the excess fluid must. not be allowed to pass through the connection: 131-50 readily that the necessary pressure. will not: be maintained in the supply connection. 6 to the motor-pump device 1:. Acccrdinglyyasabove-indicated, the compression of the'spring 12 which controls the relief valve T l will be made su-flicient to compel the desired pressure, to; bemaintai-ned in the chamber l'fi'and'in the conduit 6. For example, a pressureofwup. s. i.;may beymaintained in the. fluid supply connections to the motor pump device I by the appropriate setting of the spring T2. It will be noted that from the chamber 16 the port 50 opens into the annular chamber 25 and that the, shifter; valve 36 can never shutoff communication through the chamber 26 between the port. 56 and the opening 6|, and accordingly that whenever the pressure in the port 1-6 is; high enou'g-hto unseat: the relief valve 1| fluid mavpass into. the chamber 51 and through the'port'56, and, referring; to Figs. 6 and '7, through the chamber 26120 the conduit l3 and so back tothe source, I by way of theconduit H. In Figs. 9. and, 10,-because ofthe desirability of avoiding overlapping ports, the connection of the-conduit. 43 with. the chamber 28 is shown as made via a portion oi-the conduit 56 instead of opening into the chamber 26 separately from the port 56 and. at right angles to the communication of that portwith thechamber 28. Fig. 10., subject tothe understandingjust expressedimay be considered to show the normal position of the parts during the. operation of the motor-pumpdevi'ce I a direction to efliect winding-in of thecable 16;- in other words, the mode of operation which occurs when the vehicle is moving in a direction to shorten'the free length of the cable. It will be observed-that theshitter valve 36 occupies at this timethe position shown in Figs. 5, 6 audit), being so; heldby reasonvof the fact that the hydraulic pressurecnits lower end is: less than the-hydraulic pressurev onitsupper end by'theamount occasioned bythepresence of the spring 23 and'that, moreover, the spring operates to hold the shifter valve 36 in the position mentioned.

Let it now be supposed that the vehicle brought to'a stop. This will mean that'the' motor= pump device 1 will no longerdrive the reel to conduit 6.

7 wind in'the cable, but nothing will occur in the controlling apparatus which will result in a movementof this shifter valve 36 to reduce the pressure imposed on the motor-pump device I, and so the cable tension will be maintained undiminished when the vehicle is at a standstill.

Suppose now that the vehicle is caused to move in a direction which will necessitate the unwinding of the cable from the reel in order for such motion to take place. The motor-pump device I will then be driven in the opposite direction, and initially against the full pressure maintained by the setting of the relief valve device I I. However, the instant that the motor-pump device commences to draw fluid from the source I through the conduit l and to discharge into the conduit 6, the valve 22 will seat, and the only passage for flow of the fluid which can be established will be one opened by upward movement of the shifter valve 36 to the position shown in Figs. 7 and 9; and, because the pressure which will be built up momentarily may be in excess of the pressure imposed by the pump 3, which cannot exceed 3-00 p. s. i., or whatever other selected pressure may be fixed by the relief valve mechanism 7!, the valve 36 will move upward to the position mentioned. When this occurs the fluid pumped by the main pump 3 will pass from the chamber l5 through the port 5i into the chamber 27, through the groove between the heads of the shifter valve into the chamber 28, and freely through the conduits i3 and ii back to the source. Note that the back pressure on the main pump 3 has been completely removed except for such pressure as friction of the liquid in the passages may involve. Upward movement of the shifter valve 36 will also open a passage from'the chamber 3%] to the chamber 29, and, when the valve 65 is unseated, through the chamber 60 and port 59 to the chamber 28 and through the latter and by way of the conduits l3 and HI back to the source. The valve 65 is unseated at a much lower pressure, as above indicated, than the valve l I, say, at a pressure of 100 p. s. i. in the chamber 53, and accordingly the tension on the cable I!) will be substantially reduced and the reel may be turned backwards, driving the motorpump device 1 as a pump, with a much lower pressure in the line b than during the operation of the motor-pump device as a motor.

Now let it be assumed that the vehicle stops. The motor-pump device no longer acts as a pump and no longer delivers fluid through the The passage 45, 5! permits equalization of pressures at the opposite ends of the shifter valve 36 practically immediately, and the spring forces the shifter valve back to the position shown in Figs. 5, 6 and 10. This interrupts communication between the passages 52 and 55 and between the chamber and the conduit 13. Accordingly the pressure of the fluid in the line 6 and chamber l6 will build up to the value at which the relief valve H will be unseated. Therefore it will be evident that when the vehicle comes to a'stop conditions will automatically result which will cause the motor-pump I to be subjected to the higher pressure necessary for most efiicient winding in operations when the vehicle commences tomove in the direction where winding-in of the cable is needed. Indeed the cable tension will be immediately increased,

From the foregoing description, it will be evident that we have provided an improved automatic control valve mechanism in which a shifter valve, automatically controlled, places differently set relief valves in control of the. critical pres-i sure in accordance with different operations of the apparatus controlled and is adapted automatically to provide a free discharge for the normal operating fluid when it is not being used for motor actuation, thereby reducing power and avoiding excessive heating.

More specifically, the improved valve means will be noted to include a pair of pressure relief valves set at different pressures, a shifter valve, and a check valve, a supply passage, a vent passage, and a passage for connection to a device to be controlled by the valve means, the pressure relief valve with the higher setting, and the check valve each having its supply side constantly in free communication with the supply passage, the two pressure relief valves each having their discharge sides in free communication with said vent, the pressure relief valve with the lower setting having its supply side connectible with the passage for connection to a device to be controlled and the supply chamber connectible to the vent, both under the control of the shifter valve, and the shifter valve having opposed areas subjected to supply chamber pressure and to the pressure in the passage for connection to a device to be controlled, whereby when the pressure in said latter passage is less than the pressure in the supply passage the shifter valve will interrupt communication between the latter and the vent and between the supply side of the relief valve having the lower setting and the passage connectible to a device to be controlled, and when the pressure in the latter passage exceeds supply chamber pressure, the shifter valve means connects such passage to the supply side of the relief valve having the lower setting and the supply chamber to the vent. In certain of the claims the passage for connection to a device to be controlled by the valve mechanism, which passage is connected by the conduit 6 to the motor-pump device I, is referred to, i. e., is defined, for brevity, as a work passage.

This application is a continuation of our copending application Ser. No. 80,374, filed March 9, 1949, now abandoned, which in turn is a division of our copending application Ser. No. 731,126, filed February 26, 1947.

While there is in this application specifically described one form which the invention may assume in practice, it will be understood that this form of the same is shown for purposes of illustration and that the invention may be modified and embodied in various other forms without departing from its spirit or the scope of the appended claims.

We claim:

1. In combination, in a valve mechanism, a casing providing chambers having in them respectively a shifter valve, two relief valves, and a check valve, an external inlet connection having communication with one end of said shifter valve containing chamber and also with said chamber at a point between the ends of the latter and also with said check valve and with one of said relief valves, an external vent connection communicating with the chambers containing each of said relief valves and with said shifter valve chamber at a different point between the ends of the latter, a connection between the other relief valve and said shifter valve chamber at still a difierent point therein, and a third external connection communicating with the other end of said shifter valve chamber and with said check valve chamber.

2. In combination, .in -:a valve mechanism, a casing providing chambers having in them .re- .spectively a shifter valve, two relief valves hav ing different settings, and a check valve, an external inlet connection having communication with one end of said shifter valve containing chamber and also with said chamber at a point between the ends of the latterand also with said check valve and with one of said relief valves, an external vent connection communicating with the chamberscontainingeach of said relief valves and with said shifter valve chamber :at a second and different point between the ends of the latter, a connection between the other relief valve and said shifter valve chamber at a third point between the ends of the latter, and a third external connection communicating with the other-end of said shifter valve chamber and with said check valve chamber, said third point being nearer said other end of said shifter valve chamber than said second point is.

3. In combination, in a valve mechanism, casing means providing chambers including a shifter valve chamber and two relief valve chambers, a supply chamber, and a check valve chamber, a shifter valve in said shifter valvechamber, relief valves, having different loadings, in said relief valve chambers, a check valve in said check valve chamber, means placing said supply chamber in communication with a connection at the exterior of said casing means, means establishing communication between said check valve chamber and a'connection at the exterior of said casing means, means establishing communication between an intermediate point in said shifter valve chamber and a connection. at the exterior of said casing means, means establishing communication between said supply chamber and one end of said shifter valve chamber, means establishing com munication between said check valve chamber and the other end of said shifter valve chamber, means establishing communication between each of said relief valve chambers and the exterior of said casing means, means establishin communication between said supply chamber and the seat end of one of said relief valve chambers, means for establishing communication between the supply chamber and the seat end of said check valve chamber, means establishing communication be tween said shifter valve chamber and the seat end of the other of said. relief valve chambers; and means establishing another communication supply chamber, and in alinement with said sup ply chamber, a check valve chamber, a shifter valve in said shifter valve chamber, relief valves,-

having different loadings, in said relief valve chambers, a check valve in said check valve chamber, means placing said supply chamber in communication with a connection at the exterior of: said casing means, means establishing communication between said check valve chamber and, aconnection at theexterior of said casing means, means establishing communication between an intermediate point in said shifter valve chamber and a connection at theexterior of said casing means, means establishingcommunica--- tion between said supply chamber and one end of said shifter valve chamber, means establishing communication between said check valve cham ber andthe-otherend of said'shifter valve chamher, means establishing communication between each of said relief valve-chambers and the ex-- terior of said casing means, means establishing communication between said supply chamber and the seat end cr me of said relief valve chambers, means for establishing communication between the supply chamber and the seat of said check valve chamber, means establishing com- -munication between said shifter valve chamber and the seatend of the other of said relief valve chambers, and means establishing another communication between said supply chamber and said shifter valve chamber, said shifter valve having thereon portions bounding a fluid conduit and in one extreme position thereof connecting through said conduit said means establishing another communication between said supply cham: her and said shifter valve chamber and said means establishing communication between an intermediate point in said shifter valve chamber and 'a connection at the exterior of said casing means.

5. In combination, in a valve mechanism, cas ing means providing chambers including a shifter valve chamber and two relief valve chambers, a supply chamber, and a check valve chamber, a shifter valve in said shifter valve chamber,- relief valves, having different loadings, in said relief valve chambers, a check valve in said check valve chamber, means placing said supply chamber in communication with a connection at the exterior of said casing means, means establishing com"- munication between said check valve chamber and a connection at the exterior of said casing means, means establishing communication between an intermediate pointin said shifter valve chamber and a connection at the exterior of said casing means, means establishing communication between said supply chamber and one end of said shifter valve chamber, means establishing communication between said check valve chamber and the other end of said shifter valve chamber, means establishing communication between each of said relief valve chambers and the exterior of said casing means, means establishing communication between said supply chamber and the seat end of one of said relief valve chambers, means for establishing communication between the supply chamber and the'seat-end of said check valve chamber, means establishing communication between said shifter valve chamber and the seat end of the other of said relief valve chambers, means establishing another communication between" said supply chamber and said shifter valve chamber, and means for biasing said shifter valve towards one end of its chamber.

6. In combination, in a valve mechanism,

casing means providing chambers including a;

shifter valve chamber and two relief valve chambers, a supply'chamber, and a check valve chamber, a shifter valve in said shifter valve chamber, relief valves, having different loadings, in said relief valvechambers, a check valve-insaid check valvechamber, means placing said supply chain her in communication with a connection at the exterior of said casing means, means establishihg communication between said check valve chamber and a connectionat-the exterior of said casing means, means establishing communication between an intermediate point in said shifter valve chamber and a connection at the exterior of said casing means, means establishing communiend of said shifter valve chamber, means establishing communication between said-check,-

11 valve chamber and the other end of said shifter valve chamber, means establishing communication between each of said relief valve chambers and the exterior of said casing means, means establishing communication between said supply chamber and the seat end of one of said relief valve chambers, means for establishing communication between the supply chamber and the seat end of said check valve chamber, means establishing communication between said shifter valve chamber and the seat end of the other of said relief valve chambers, means establishing another communication between said supply chamber and said shifter valve chamber, means for biasing said shifter valve towards one end of its chamber, and means for providing a restricted communication between the opposite ends of said shifter valve chamber.

'7. In combination, in a valve mechanism, casing means providing chambers including a shifter valve chamber and two relief valve chambers, a supply chamber, and a check valve chamber, a shifter valve in said shifter valve chamber, relief valves, having different loadings, in said relief valve chambers, a check valve in said check valve chamber, means placing said supply chamber in communication with a connection at the exterior of said casing means, means establishing communication between said check valve chamber and a connection at the exterior of said casing means,;means establishing communication between an intermediate point in said shifter valve chamber and a connection at the exterior of said casing means, means establishing communication between said supply chamber and one end of said shifter valve chamber, means establishing communication between said check valve chamber and the other end of said shifter valve chamber, means establishing communication between each of said relief valve chambers and the exterior of said casing means, means establishing communi cation between said supply chamber and the seat end of one of said relief valve chambers, means for establishing communication between the supply chamber and the seat end of said check valve chamber, means establishing communication between said shifter valve chamber and the seat end of the other of said relief valve chambers, means establishing another communication between said supply chamber and said shifter valve chamber, means for biasing said shifter valve towards one end of its chamber, and means for providing a restricted communication between the opposite ends of said shifter valve chamber, said shifter valve so constructed and the connections with its chamber so arranged that in op-- posite positions of said shifter valve said supply chamber is respectively connected by said shifter valve with the exterior'of said casing means and cut off from such communication except past one" of said relief valves.

8. In combination, in a valve mechanism; casing means providing chambers including a shifter valve chamber and two relief valve chambers, a supply chamber, and a check valve chamber, a shifter valve in said shifter valve chamber,

relief valves, having different loadings, in said relief valve chambers, a check valve in said check valve chamber, means placing said supply chamber in communication with a connection at the exterior of said casing means, means establishing communication between said check valve chamber and a connection at the exterior of said casing means, means establishing communication between an intermediate point in said shifter valve chamber and a connection at the exterior of said casing means, means establishing communication between said supply chamber and one end of said shifter valve chamber, means establishing communication between said check valve chamber and the other end of said shifter valve chamber, means establishing communication between each of said relief valve chambers and the exterior of said casing means, means establishing communication between said supply chamber and the seat end of one of said relief valve chambers, means for establishing communication between the supply chamber and the seat end of said check valve chamber, means establishing communication between said shifter valve chamber and the seat end of the other of said relief valve chambers, means establishing another communication between said supply chamber and said shifter valve chamber, means for biasing said shifter valve towards one end of its chamber, and means for providing a restricted communication between the opposite ends of said shifter valve chamber, said shifter valve so constructed and the connections with said shifter valve chamber so arranged that in opposite positions of said shifter valve said check valve chamber is respectively placed in communication with one of said relief valves and cut off from such communication.

9. In combination, in a valve mechanism, casing means providing chambers including a shifter valve chamber and two relief valve chambers, a

supply chamber, and a check valve chamber, a

shifter valve in said shifter valve chamber, relief valves, having different loadings, in said relief valve chambers, a check valve in said check valve chamber, means placing said supply chamber in communication with a connection at the exterior of said casing means, means establishing'communication between said check valve chamber and a connection at the exterior of said casing means, means establishing communication between an intermediate point in said shifter valve end of one of said relief valve chambers, means for establishing communication between the sup ply chamber and the seat end of said check valve chamber, means establishing communication between said shifter valve chamber and the seat end, of the other of said relief valve chambers, means establishing another communication between said supply chamber and said shifter valve chamber, means for biasing said shifter valve towards one end of its chamber, and means for providing a restricted communication between the opposite ends of said shifter valve chambensaid shifter valve so constructed and the connections with said shifter valve chamber so arranged that in opposite positions of said. shifter valve said supply chamber is respectively connected by said shifter valve with the exterior of said casing means and cut off from such communication except past one of said relief valves and said check valve chamber is respectively connected with the other of said relief valves and cut off from such communication. j

10. In combination, in a valve mechanism, a

pair of pressure relief 'va'lves'setat different'pressures, a shifter valve, and a check valve; a' supply passage, a. vent.' passage, and a work passage for connection to aideviceto be controlled, means for continuously connecting the supply side of the pressure relief valvev having the. higher. setting in free communication with the supply passage and the dischargeside. of the pressure. reliefi'valve having the higher setting continuously in free com: munication with the vent passage, means forconnecting the. supply side ofsaid check valve continuously, in free communication with the supply passage and for continuously connecting the discharge side of said check valve in free communication with the work passage, means for continuously connecting the discharge side of the pressure relief valve having the lower setting in free communication with said vent passage, means controlled by said shifter valve for connecting the supply side of said pressure relief valve having the lower setting with the work passage, means controlled by said shifter valve for connecting said supply passage with said vent passage, and means for subjecting the opposite ends of said shifter valve respectively to the pressure in the supply passage and to the pressure in the work passage.

11. In combination, in a valve mechanism, a pair of pressure relief valves set at different pressures, a shifter valve, and a check valve, a supply passage, a vent passage, and a work passage for connection to a device to be controlled, means for connecting the supply sides of the pressure relief valve with a higher setting and the check valve constantly in free communication with the supply passage, means for connecting the discharge sides of the two pressure relief valves constantly in free communication with the vent passage, passage means for connecting the supply side of the pressure relief valve with the lower setting with the work passage and for connecting the supply passage to the vent passage, both under the control of the shifter valve, said shifter valve having opposed areas facing longitudinally thereof, and means for subjecting one of said areas to the supply passage pressure and the other to the presure in the work passage, whereby, when the pressure in said latter passage is less than the pressure in the supply passage the shifter valve will be moved in one direction, and when the pressure in the work passage exceeds supply passage pressure the shifter valve will be moved in the opposite direction, said shifter valve controlled passage means so arranged that in the first mentioned position of the shifter valve such valve will interrupt communication between the supply passage and the vent passage and between the supply side of the relief valve having the lower setting and the work passage, and in the second position of the shifter valve the latter will connect the work passage to the supply side of the relief valve having a lower setting and connect the supply passage to the vent passage.

12. In combination, in a valve mechanism, a pair of pressure relief valves, a shifter valve, and a check valve a supply passage, a vent passage, and a work passage for connection to a device to be controlled, means for continuously connecting the supply side of one of said pressure relief valves in free communication with the supply passage and the discharge side of said same pressure relief valve continuously in free communication with the vent passage, means for connecting the supply side of said check valve continuously in free communication with the supply passage and continuously connecting the discharge side of saidc'heck valve in free communication with the work passage, means for continuously connecting the discharge side'of the other pressure relief valve in free communication with the-vent passage; means controlled" bythe shifter-valve'for connecting the supply side of said'last'mentioned pressure relief valve with the-workpassag-e,means controlled by the shifter valve fer connec-ting" the supply passage with the vent passage, and'means for-subjecting-the opposite ends of theshifter valve respectively to-the pressure in the 'suppl-y passage and to-the pressure in the work passage.

13. In combination, in a valve mechanism, a pair of pressure relief valves set at difierent pressures, a shifter valve, and a check valve, 2. supply passage, a vent passage, and a work passage for connection to a device to be controlled, means for continuously connecting the supply side of one of said pressure relief valves in free communication with the supply passage and the discharge side of said same pressure relief valve continuously in free communication with the vent passage, means for connecting the supply side of said check valve continuously in free communication with the supply passage and continuously connecting the discharge side of said check valve in free communication with the work passage,

means for continuously connecting the discharge side of the other pressure relief valve in free communication with the vent passage, means controlled by the shifter valve for connecting the supply side of said last mentioned pressure relief valve with the work passage, means controlled by the shifter valve for connecting the supply passage with the vent passage, means for subjecting the opposite ends of the shifter valve respectively to the pressure in the supply passage and to the pressure in the work passage, and means for providing a restricted communication between the opposite ends of said shifter valve.

14. In combination, in a valve mechanism, a casing providing a chamber having in it a fluid thrown shifter valve, said casing having associated with it a first and a second relief valve and a check valve each having an upstream and a downstream side, a fluid inlet having connections with the upstream side of said check valve and of said first relief valve, a connection with said shifter valve chamber controllable by said shifter valve and a connection for transmitting fluid for throwing said shifter valve in one di rection, an external vent connection for said shifter valve chamber connectible by said shifter valve with the first mentioned connection with said shifter valve chamber, connections for conducting to vent fluid from the downstream sides of both of said relief valves, a connection between the upstream side of said second relief valve and said shifter valve chamber at a point alternatively covered and uncovered by said shifter valve, and an external connection communicating with the downstream side of said check valve chamber and having a connection for transmitting fluid for throwing said shifter valve oppositely to said first direction.

15. In combination, in a valve mechanism, a casing providing a shifter valve chamber containing a shifter valve, and having associated with it two relief valves and a check valve each having an upstream and a downstream side, a fluid supply connection communicating with the upstream side of said check valve and of one of said relief valves and further communicating with said shifter valve chamber both at one end of the latter and at a point spaced from such end but between the two ends of said shifter valve chamber, a vent connection communicating with said shifter valve chamber at a point between the ends of the latter difierent from the valve and said shifter valve chamber at a point 10 in the latter between its ends and different from each of said other two points, and a work connection communicating with the other end of 16 said shifter valve chamber and with the down.- stream side of said check valve.

CHARLES '1. BALL. RICHARD T. HAIR.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,395,302 Slomer Feb. 10, 1946 2,474,122 .Schneck June 21, 1949 2,477,669 Stephens Aug. 2, 1949

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