US1842569A - Pump - Google Patents

Description

J. R. RIQHER 1,842,569

PUMPA med oct. 2a, 1929 z snaets-sheez 1 Jam. ma, m32,

J. R. mel-1ER 1,842,569

PUMP Filed not, ze. 1929 2 sheets-sheen 2 @www Patented Jan. 26, 1932 UNITED STATES JOSEPH R. RICHEB, OF GAK PARK', ILLINOIS, ASSIGNOR T0 .TENS P. N'IELSEN, EMMA A.

PATENT orricls.l f

:HIGHER A ND JOSEPH R. RICHER,ALL 0F OAK PARK, ILLINOIS, TBUSTEES 0F THE :EY-PRESS PUMP COMPANY, OF CHICAGO, ILLINOIS, A. CMMONLAW TRUST PUMP , Application mea october 26, 1929. Serin-im. 402,628.

rl'he invention relates generally to'pumps of the piston and cylinder type and more particularly it relates to this type of pump wherein a plurality of cylinders are disposed about and parallel to the axis of tledrive shaft and the pistons are actuated bya wobble plate. carried by the shaft.

rl`he primary object of the invention is to provide a new and improved pump of this type of simplilied construction and particularly adapted for pumping large quantities of liquid at extremely high pressures.

Another object is to provide such a pump embodying a simplified valve mechanism arranged to utilize the rotary movement of the drive shaft to promote rapid and complete iiiling and discharging of the cylinders so lhat the pump may be used efficiently to rereive liquid at an unusually low -pressure and to discharge a constant flow of liquid at a uniform and comparatively high pressure. Another object is to provide such a pump having an cxtremelysimple means to prevent rotary movement of the wobble plate.

Another object is to provide a pump of this character having an' improved wobble plate construction adapted to facilitate the manufacture and assembly of the pump.

Other objects and advantages will become apparent from the following description ,taken in connection with the accompanying drawings in which:

lfigure 1 is a central vertical sectional view ot a pump embodying theinvention in its preferred form.

lig. 2 is a fragmentar sectional View taken along the line 2 2 of 4`ig.` 1.

lig. 3 is a fragmentary horizontal sectional view of the pump .taken along the line 3--3 of lFign/l.

llt-ig. 4 is an end 'view of the pump with one end plate removed so as to show the construction of the valve disk.

lf'or purposes of disclosure the preferred form of the invention is illustrated in the drawings and will hereinafter be described in detail as applied to a particular form of pump, but it is to be understood that this dis closure is not `intended as a limitation of the invention-to this type of machine, it being vtherein spaced from the two end plates to forma cylinder block 13. From the sides of the casing 10 a plurality of legs 14 project so that the casing may be'readilyinounted.

In the cylinder block 13 a plurality of cylinders 15 are formed disposed in circumferentially spaced `relation (Fig. 4f)I about the i axis of the casing and parallel thereto, the cylinders in the present case extending entirely through the web which 'forms the c linder block, as shown' in Fig. 1. A plurality of pistons 16 are provided, one slidably mounted in each of said cylinders and-for the purpose of actuating the pistons a drive shaft 17 is rotatably mounted in the easing 10 for rotation on the axis of the casing. The drive shaft 17 extends through an aperture 18 in the end plate 11 sok that it may be driven by suitable means not shown) connected to the outer end thereof. In the present case the drive shaft 17 extends through the cylinder block 13 andthe inner end thereof is rotatably supported by an antifriction bearing 19 positioned in a recess 20formed in the end plate 12. .The shaft 17 is also rotatably supported.

at spaced points by the cylinder block 13 and the other end wall 11 by means of a pair ofoppositely disposed tapered roller bearings 21 and 22 (Fig. 1) which serve to hold the shaft in the desired axial position.

In order that rotation of the drive shaft 17 may serve to reciprocate the pistons 16- the shaft has an enlarged portion 23 (Fig. 1) between the bearings 21 and 22 disposed at an angle to the'rotative axis of the shaft, and a wobble plate 24 is rotatably sup orted on theangular portion 23 in perpen icular relation thereto by means of oppositely disposed tapered roller bearings 25 and 26. As

the drive shaft 17 is rotated the axis of the angular portion 23 describes a cone and since the wobble plate 24 must at all times be perf pendicular to the axis of the angular portion 23, it will be seen that any point on theside edge thereof (the plate 24 being held against rotation relatively t'o the cylinder block 13) will move back and forth toward and from the cylinder block 13. This movement of the edge of the plate is utilized to reciprocate the pistons 16 and to this end a plurality of piston rods 27 (Fig. 1) are provided, the

opposite ends of each piston rod being connected respectively to one of the pistons and to the edge of the wobble plate. The vconnections at the ends of the piston rods 27 are in the nature of ball and socket joints formed by balls 28 on the ends of the piston rods engaging suitable sockets on the wobble plate and the pistons. l

In the present case the sockets onk the wobble plate -24 are provided by means of spherical seats 29 formifinithe plate to engage the end surface-of the balls-2S and a pair of flanged annular members 30 and 31 of different sizes secured in fixed position on the wobble plate 24 and-extending over the i serves as an abutment again st which the outer race 34 of the tapered roller bearing 26 bears. The bearing 25 is arranged to exert a thrust away from the cylinders 15 and the inner race 35 of the bearing is held in position against a shoulder 36 on the angular portion 23 of the shaft by means of a nut 37. a rlhus the bearing 26 serves to hold the :annular member 31 in its operative position.

The inner annular member 31 also serves as an abutment against which the outer race 38 of the opposing thrust bearing 425 tits the inner race 39 of this bearing being positioned on the angular portion 23 of the shaft in engagement with the shoulder 40 and being held in such engagement by action of the nut 37 on the opposing bearing 26.

The socketsJ-i-n the pistons 16 are preterablyformed so that the piston rods project a considerable distance into the pistons and to this end each piston has a threaded bore 41 of considerable depth extending longitudinally thereof and provided with a spherical seat 42 at its inner end. To vhold the ball 28 against the seat 42 an exteriorly threaded nut l43 surrounding the rod 27isserewed into the threaded bore 41, a spherically shaped seat 44 being lformed from the inner end of the nut to engage the surface ofthe ball 28. The I nut 43 is preferably ofV sutlicient length so that it projects out of the bore 4l to receive a lock nut 45 on its outerendwhich may be screwed into engagement with the end of the piston 16 to prevent displacement of the nut 43. During the operation of the pump the piston rods must oscillate radially of the casing in" the sockets in the pistons 16 and the central opening in the retaining nut 43 is therefore of suflicient size to permit such movement.

During rotation of the actuating shaft 17 the wobble plate 24 tends to rotate therewith and means of a simple character is preferably provided to prevent such rotative movement. VIn the present case one of the piston rods 27 is utilized for this purpose and as shown in section in Fig. 2, this piston rod has parallel flattened sides 46 formed thereon which are engagedby suitable opposed parallel surfaces 47 formed in the central opening in the retaining nut 43. Thus the piston rod 27 may only move radially with respectto the drive shafty 17 in a plane which passes through the rotative axis of the shaft .17 and prevents rotative movement of the wobble plate 24. It will be noted that even when the 4piston16 is withdrawn from the cylinder to the position occupied by the lower piston in Fig. 1` the piston has a considerable bearing against the side walls ot the cylinder so that the piston is maintained in proper alinelnent in the cylinder at all times. lt will also be noted that-the flat sides 46 on the piston rod shown in Fig. 1 engage the flat surfaces on the retaining nut 43 at a considerable distance from the pivotal axis of the piston rod so that the piston rod has a considerable leverage for preventing rotative movement of the wobble plate 24.

1n practice,the cha1nber48 (Fig. 1) formed in the casing between the cylinder blockpll and the .end plate 11 is filled with oil so as to insure properlubrication of the wobble plate 24 and the piston rods and to prevent oil from leaking from the chamber, a stuiting box is positioned about the shaft 17. The stulling box is formed by a collar 49 (Fig. 1) bolted to the end plate 11 in surrounding relation to the shaft and having a counter bore 5 0 filled with suitable packing which is comressed by a spring pressed sleeve 51 extending into the counter bore.

As the pistons 16 are reciprocated by rotation of the actuating shaft 17 the intake and discharge of luid is controlled by suitable valve means moving in timed relation to the movement of the pistons. Preferably the valve means is driven directly from the drive shaft 17 and is arranged to impart rotary movement t0 the Huid as it passes thereith through and to utilize the centrifugal force resulting from such movement to facilitate and promote passage of the fluid to and from the cylinders.

1n the form herein shown the valve means comprises a disk 52 keyed on the actuating shaft 17 between the cylinder block 13 and the end plate 12 so as to rotate with the shaft 17. The valve disk 52 controls the passage of Huid into the cylinders from an annular supply or intake passage 53 (Figs. 1 and 3) 'formed in the end plate 12 and also controls passage of huid fromthe cylinders 15 into an annulardischarge passage 54 also formed in the plate 12 and spaced radially outwardly from the supply passage 53.

1n the valve disk 52 a pair of arcuate ports 55 and 56 (Figs. 3 and 4) are formed, the port 55 constituting the intake opening and communicating at one side of the plate 52 with the annular intake passage 53 while the port 56 constitutes the discharge openingof the valve and communicates at all times wlth .the annular discharge passage 54. At the other side of the valve disk 52, the two ports and 56 communicate with the cylinders, the two ports being of such an arcuate length that their ends are 4spaced. apart a distance slightly greater than the width of the cylinders 15, as shown in Fig. 4, so that any one 'cylinder cannot be in communication with the intake and discharge ports at the same time. Thus when a pump having four cylinders is used, as in the present case, the discharge passage 54 is always in communication with at least one of the cylinders and a constant uniform flow of fluid is therefore maintained. This result could obviously be obtained with other nulnbers of cylinders.

ln order to facilitate the How of the fluid to and from the cylinders and thus insure complete filling and discharge thereof, the valve disk 52 is made of considerable thickness so that the ports 55 and 56 will contain a comparatively large quantity of fluid and will impart rotative movement to the liquid in the ports about the axis of the drive shaft 17. rlllhe centrifugal force resultingA from this rotative movement of the fiuid is utilized to facilitate the filling and discharge of the cylinders and to this end thevalve ports 55 and 56 are formed so as to extend through the disk 52 at an angle to the rotative axis thereof as shown in Fig. 3, the intake port 55 sloping radially outwardly from the end which communicates with the supply passage 53 while the discharge port 56 slopes radially outwardly from the end which communicates with the cylinders 15.

Because of the comparatively great arcuate extent of the ports 55 and 56 in the valve disk 52, a plurality of radial Webs 57 are provided which extend across the valve ports to strengthen the outer edge of the disk. The webs 57 are grooved or cut in at their edges as shown at 58 in Fig. 3 so that the fluid may pass around the edges of the web and render the ports, in effect, continuous. However, the webs 57 assist win imparting rotary movement to the fluid and thus aid in causing movement of the fluid into and out of the cylinders.

It 'will be noted that the valve ports 55 and 56 are of considerable radial width and that the ends adjacent the'eylinders 15 are centered on the axes of the cylinders so that unusually largey intake and discharge passages are provided for the fluid. Durin the .operation of the pump the pressure o the fluid in the discharge side of the pump acts constantly on the surface 58v of the discharge port 56 to urge the valve disk 52 away from the cylinders, so as to equalize to a large extent the pressure of the fluid in thepassage 54 which urges the disk in the opposite direction. This equalizing action materially reduces the pressure and wear on the thrust bearings which maintain the shaft 17 in proper axial position. By reason of the finer and more permanent adjustment thus made possible inthe bearings, a smaller clearance may be provided between the valve member 52 and the cylinder block and the end plate 12 so as to prevent leakage therebetween.

Since the pump is intended for working at high pressures, there is always danger of building up high pressures in the oil chamber 48 about the wobble plate, this being caused by leakage of the Ihigh pressure fluid from the cylinders 15 about the pistons 16. 'lo guard against damage due to such r'essures, a relief valve is preferably provide for the chamber 48 and in case the pump is to be'used for pumping oil, this valve may bearranged to discharge into the intake side of the pump. Thus in the form shown an axial bore 59 (Fig. 1) is formed in the shaft 17 extending from the end which is positioned in the recess 20 to a point lying Within the chamber 48, a transverse passage 60 extending from the bore 59 to the outside of the shaft to columnnicate with the chamber 48. Near the end of the shaftgl'?, the bore 59 is enlarged to receive a ball check valve 61 which is pressed to closed position by an expansive coiled spring 62 held within the bore 59 by a hollow tap screw 63 which is screwed into the bore 59 and serves to hold the .inner race of the bearing 19 in position. Oil which is forced past the ball valve 61 by excessive pressure in the chamber 48 is discharged from the bore 59 into the recess 20 in the end plate 12 through a central bore 64 formed in the screw 63 and this liquid is then discharged into the intake passage 53 of the pump through a recess 65 (Figs. 1 and 4) formed in one side ofthe valve disk 62. The recess 65 together with other recesses 66 (Figs. 1 and 4) may be positioned in the valve disk so as to dynamically balance the disk.

lVhen the parts of the pump are in the positions shown in the drawings the fluid has been exhausted from the upper cylinder 15 (lf i 4), the left hand cylinder has been parshown, the pistons 16 and the valve disk 52 are moved so that the discharge port 56 isV brought into communication with the lower or filled cylinder 15and the piston moves along its discharge stroke. At the same time, the intake port 55 is moved into communication with the upper or empty cylinder 15 and as the piston 16 thereof is withdrawn, the cylinder is filled with liquid, the complete filling ofthe cylinder being facilitated by the centrifugal force imparted to the fluid by the rotating valve disk and acting in the angularly extendingfintake port 55 to cause movenient of the fluid into the cylinder.4 Since the valve disk acts to cause movement of the fluid into the cylinders, the filling of the cylinders is insured eventhough the fluid is supplied at-an unusually low pressure.

The same action progresses from cylinder to cylinder and the discharge port 56 is at all times in communication with at least one of the cylinders so that a constant flow of liquid is provided at a substantially uniform pressure. .l

From the stand oint of manufacture and assembly, the wob le plate construction is of particular advantage du'e to the simplicity of the various parts i thereof. In this connection it should be noted that the nut 37 serves to hold the flanged annular member 31, the plate 24, and thev two bearings 25 and 26 in assembled relation as well as to hold the plate assembly in position on the shaft 17 and since the nut holds the annular member 31 in place, it assists in maintaining the piston rods 27 in proper relation to the wobble plate.

From the foregoing it will be apparent that the invention provides an exceedingly simple and efficient pump which will provide a constant ow of fluid at a uniform pressure and which will operate efficiently when supplied with fluid at a low pressure.` It -will also be seen that the use of one of the piston rods to prevent rotation of the wobble plate serves to materially simplify the pump.

I claim as in invention:

1. A pump o the lcharacter described comprising, in combination, a tubular casing having a transverse web therein spaced from both ends thereof to form a cylinder block, a pair of plates closing the ends of said casing, a

rotatable drive shaft extending into said casing through one of saidI end plates and through said cylnder block and having a central bearing -said cylinder block and a` bearing in each of said end plates, said cylinder block having a plurality of cylinders formed therein parallel to and spaced circumferentially about the axis of said shaft, a piston mounted in each of said cylinders, a wobble plate rotatably mounted on said drive shaft between its central bearing and one end bearing disposed at an angle to the rotative axis of said shaft and arranged when said shaft is rotated'to aetuate said pistons successively, a valve disk mounted on said shaft between the central bearing and the other end bearing, said disk extending across the open ends of said cylinders in contact with the end of the cylinder block and having circumferentially spaced intake and discharge openings arranged to communicate with said cylinders,

and supply and discharge passages formed in the adjacent end plate arranged to communicate with the corresponding valve openings in said disk.

2. A pump of the character described comprising, in combination, a cylindrical casing having a transverse web-therein spacedfrom both ends thereof to form a\ cylinder block, a pair of plates closing the ends of said casing, a rotatable drive shaft extending into said casing through one of said end plates and through said cylinder block and having a central bearing in said' cylinder block, a bearing in both of said end plates, said cylinder block having a plurality of cylinders formed therein parallel to and spaced circumferentially about the axis of said shaft, a piston mounted in each of said cylinders, means on said drive shaft between its central bearing and one end bearing arranged when said shaft is rotated to actuate said pistons,

a valve disk mounted on said shaft between the central bearing and the other end bearing, said disk extending across the open endsof said cylinders in contact with the end of the cylinder block and having circumferentially spaced intake and discharge o Vnings I arranged to communicate with said cy inders, and supply and discharge passages formed inthe adjacent end plate arranged to coinmunicate with the corresponding valve openings in said disk. y

3. A machine of the character described comprising a tubular casing having a web formed integrally therewith and extending transversely across said casing intermediate the ends thereof to form a cylinder block, plates closing the ends of said casing, a ro-y tatable shaft extending into said casing through one of said end plates and extending through said web, a plurality of cylinbetween said web and one end plate driven llt tti

lill

till

intake and discharge ports therein for con-I trolling the passage of fluid to and from said cylinders.

ll. A machine of the character described4 comprising a hollow casing having a cylinder lolock extending 'transversely thereof, a plurality of cylinders extending through said block, pistons in said cylinders, means in said casing on one side of said block for actuating said pistons, a shaft rotatably mounted in said casing parallel to said cylinders and arranged to be rotated in timed relation to said piston actuating means, thrust bearings to maintain the shaft in proper axial position, a valve disk on said shaft on the other side of said cylinder block having its opposite sides in sliding engagement respectively with said block and a part of said casing, said valve disk and said casing providing a pair of annular passages centered on the axis of said shaft, one of said passages being for loW pressure Huid and the other for high pressure fluid, said disk having intake and discharge ports each communicating with one of said passages and With said cylinders, said disk being arranged so that fluid under pressure in said cylinders is applied to said disk to counteract the force exerted by the fluid in said annular passages.

5. rt machine of the class described comprising a cylinder block having a plurality of annularly spaced parallel cylinders formed therein, pistons in said cylinders, means for actuating said pistons, a rotatable shaft, 'thrust bearings to maintain the shaft in proper axial position, means lfor conducting fluid to and from said cylinders, and a valve disk on said shaft and associated with said fluid conducting means to control the passage of tluid into and out of said cylinders, said disk and said conducting means being arranged so that the fluid on the high pressure side of the machine acts on both sides of valve disk whereby to avoid excessive thrust on said bearings.

t. A pump having a cylinder block with a plurality of cylinders formed therein parallel to each other and arranged in circumferentially spaced relation about an axis in said block, said cylinders extending entirely through said block, a plurality of pistons reciprocably mounted one in each of said cylinders, means on one side of said block operable to actuate said pistons successively, a

4 shaft rotatably mounted on said axis and arranged to move in timed relation to the piston actuating means, a valve disk on said shaft having one side thereof in abutment "with the other side of said cylinder block and extending across the open ends of allof said cylinders, a plate in abutment'with the other side of said valve disk having radially spaced annular intake and discharge passages therein, and circumferentially spaced arcuate intake and ldischarge openings in. said valve disk, each being in constant communication with the corresponding passage in said late.

7. In a pump lhaving a plurality o cylinders with pistons therein and means for actuating said pistons, a shaft arranged to rotate in tilned relation to the movement of said pistons, a valve disk mounted on said shaft for rotation therewith, means providing radially spaced annular intake and-dis l charge passages on one side of said valve disk,

said disk having circumferentially spaced' arcuate valve ports formed therein, radial Webs extending across said ports to strengthen the disk and to cause circular movement of the fluid with the disk as the fluid passes through said ports, one end of one of said ports communicating at all times with said intake passage and theother end of said port communicating with said cylinders successively during rotation of the disk, the othery port communicating with said cylinders and the discharge passage, both of said ports extending angularly away from the rotative axis of said disk so that the distance of said portsfrom said axis becomes progressively greater along the path and in the direction of movement of the liquid being pumped.

8. In a pump having a cylinder block with a plurality of open ended actuating said pistons, a shaft arranged to rotate in tlmed relation to said pistons, a valve disk mounted on said shaft for rotation therewith and having one side in contact With one side of said Cylinder block and extending across the open ends of said cylinders. in closing relation thereto, means providing radially spaced annula-r intake and discharge passages on the other side of said valve disk, the discharge passage being of the greatest diameter, said disk having circumferentially spaced arcuate valve 'ports formed therein, one end of one los of said ports communicating at all times With said intake passage and the other end of said port communicating With said cylinders successively during rotation of the disk, said last mentioned end of said port extending across the ends of the cylinders substantially along a diameter thereof, the other port communicating similarly with the cylinders andsaid discharge passage.

9. A pump comprising, in combination, a cylinder block having a cylinder therein, a piston reciprocable in said cylinder, means for reciprocating said piston, means for conducting fluid to and 'from said cylinder, and a rotatable valve member driven in timed relation to the movement of said piston for controlling the passage of fluid into said cylinder said member having a passage formed therethrough arranged. to .impart lcircular movement to the fluid passing therethrough and said passage extending angularly away from the rota-tive axis of saidmember in a direction arranged to utilize the centrifugal force of-'such rotative movement of the fluid to facilitate the passage. of the fluid through said valve means and into said cylinder.

10. A pump-having a cylinder block with a cylinder formedtherein extending entirely through said block, apiston reciprocably mountedy in said cyl1nder,'means on onel end of said block operable to actuate said piston,

a shaft rotatably mounted parallelv 'to the' Aaxis of said piston arranged to move in timed relation t'osaid piston, a valve disk on said shaft having one side thereof sidably en? gaging the other endof said cylinder` block and extending across the open'end of said cylinder in. closing relation thereto, means on the other side of said valve disk havin intake and discharge passages therein space radially relativel to said disk, and circumferentially space intake and'discharge vopenings in said valve disk 'arranged to cause movement of the fluid circumferentially about said, axis and radially away from said axis as it passes through said openings dur ing operation of the pump.

11. In a vmachine ofv the character dev scribed, the combination with a drive shaft'v having an enlarged angularly disposed portion'with a shoulder at one end thereof, of a centrally apertured wobble plate having a plurality of spherically shaped seatsformed at one side thereof, .said plate being tioned in surrounding relation to sald portion, a plurality of piston rods each having a ball at one end engaging one of said seats,

means vforming a plurality of cylinders ex.

' tending longitudinally of said shaft, pistons in said cylinders connected to saidv piston rods, a flanged annular member fixed on said plate and .engaging .the outer sides of said 'balls to .hold them againstsaid seats, a pair of opposed thrust bearings interposed between said plate and said angular portion of the shaft, the inner race of one of said bearings being inbutment' with said shoulder, a second annu ar member` surrounding the otherv .of said bearings and having an inturned flange interposed between'the outer races of the two bearings, an out-turned fiange on said second member engaging the inner sides of said balls to hold them against said seats, and a nut engaging said shaft and 'the innerl'ace of said other bearing to maintain said plate, said bearings and said second annular memberl in "assembled relation on said shaft.

12. In amachine of the character describedyhaving a plurality of pistons vand means forming cylinders for said pistons the' combination with a driveshaft having an angularly disposed portion, of an apertured POSi- `asiatica wobble-'plate positioned on said angular por.

tion, bearing means rotatabl supporting said plate on said portion, sai plurality of spherically shaped seats formed in one lside thereof, a plurallty of piston rods one connected to each piston and each havin a ball on one end thereof engaging one of sai seats, a retaining means for holding said balls in position on said seats, and a nut on said shaftoperable to hold said plate and.

said retaining means in aembled-relation andV in position on said shaft. Y

13. A pump havin a casing, a rotatable actuating shaft extending into said casing, a wobble plate rotatably mounted on said shaft .in angularly disposed relation thereto, a plus rality of cylinders in said casing parallel to said shaft, valve controlled intake and dischar e means for said cylinders, a plurality of plston rods each having their opposite ends connected respectively to the wobble plate having a l plate and to one ofrsaid pistons by means of about the axis of said shaft, means for 'comducting fluid to and from said cylinders, a wobble plate rotatably mounted on said shaft in angularly disposed relation'thereto, and piston rods connect-ing said pistons to said wobble plate, each of said piston rods havinP a universal connection wlth said plate one of said piston rods being connected to its fpiston so as to'A permit plvotal movement of said 'rod relative to said tpiston in aA plane passing through the rota e axis of s ald shaft and to prevent other relative movement p therebetween.

15. A jpump having, in combination, a

cylinder' block havin a plurality of cylinders therein, a pistoni-in each cylinder, means forming a chamber on one side of said block, actuating means for said plstonsmounted 1n vsaid chamber, a shaft connectedl to and driven with said means andv extending through said block, valve mechanism on the other side of said cylinder block to control the-intake and discharge of fluid from said cylinders, means for supplying fluid to and conducting it from said valve mechanism, and a pressure relief passage for said chamber formed in said shaft-and having a" check "valve therein, said` passage communicating valve mechanism.

16. A machine of the comprising means formin a luralit of cyl- -inders, pistons in said cy in ers, va ve conwith said chamber and the supply side of sa/id character described lil) la'olled means for supplyingr fluid to and conducting it away from said Cylinders, means .at one end of said cylinders for actuating said pistons, a closed casing sux-rounding said actuating means, and means forming a pressui-e relief passage for said casing, ancl a uheclc valve in said passage, said passage comnnlnieating with said casing andthe 10W pressure, side of said valve controlled means.

lin testimony whereof, l have hereunto allixed my signature.

JOSEPH R. RICHER.

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