US2458985A

US2458985A - Hydrodynamic machine

Info

Publication number: US2458985A
Application number: US609584A
Authority: US
Inventors: Ferris Walter; James K Douglas
Original assignee: Oilgear Co
Current assignee: Oilgear Co
Priority date: 1945-08-08
Filing date: 1945-08-08
Publication date: 1949-01-11
Anticipated expiration: 1966-01-11

Description

Jan. 11, 1949. w. FERRIS ET AL 2,458,935

I HYDRODYNAMIC MACHINE I Filed Aug 8,1945 4 Sheets-Sheet 2 FIG. '2

/ Y J ES K. GLAS 6 g v I I TERuw szvroRzlzg;

11, 1949. I w FERR|$ ETAL I M 2,458,985

HYDRODYNAMIC MACH'INE Filed Aug. 8, 1945 I 4 Sheets-Sheet 3 nvvszvrons: WALTER FERRIS JAM ES K. DOUGLAS ATTORNEY Jan. 11, 1949.

w. FERRIS ET AL HYDRODYNAMI C MACH INE 4 Sheets-Sheet 4 FIG.

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Filed Aug. 8, 1945 w/AW INVENTORS: WALTER FERRIS JAMES K. DOUGLAS BY WATTORNEY Patented Jan. 11, 1949 HYDRODYNAMIC MACHINE Walter Ferris, Milwaukee, and James K.Douglas,

Shorewood, Wia, assignors to The Oilgear Company, Milwaukee, Wis; a corporation of Wisco'nsin Application August 8, 1945. Serial No. 609,584

12 Claims. (01. 103-161) This invention relates to hydrodynamic machines of the type having a rotatable cylinder barrel, pistons and cylinders extending into the cylinder barrel from the circumferential periphery thereof and a thrust member arranged around the cylinder barrel in engagement with the outer ends of the pistons, the thrust member being eccentric to the cylinder barrel when the machine is performing useful work.

Such a machine will function as a pump when it is driven mechanically or it will function as a motor when it is supplied with liquid under pressure. In order to simplify the following explanation of the invention, the machine will be referred to herein as a pump but it is to'be understood that a machine embodying the invention will also function as a motor and that designating the machine as a pump in no way limits the invention to pllmp.

When a pump of this type is driven mechanically and its thrust member is eccentric to the cylinder barrel, each piston will move outward and draw liquid into its cylinder during one halfrevolution of the cylinder barrel and it will be forced inward by-the thrust member and expel liquid from its cylinder during the other halfrevolution of the cylinder barrel.

' Pumping forces are thus transmitted from the thrust member through the inward moving pistons to the liquid in the cylinders thereof, and these forces act upon the cylinder barrel and tend to move it at right angles to its axis of rotation, thereby imposing a heavy load upon the bearings which support the cylinder barrel. These bearings must thus be large enough to rotatably support the cylinder barrel when pump pressure and consequently the pumping forces are maximum. The large size of the cylinder barrel bearings and the loads imposed thereon by the pumping forces causes considerable bearing losses in the prior pumps and also causes the over all dimensions and weights of the prior pumps to be greater than would be necessary if the bearings and bearing loads were smaller.

The present invention has as an object to provide a construction in which the loads imposed upon the cylinder barrel bearings are reduced to a minimum.

Another object is to provide a construction in which the cylinder barrel is substantially hydrostatically supported and balanced.

A machine constructed according to the inand capacity and has a higher mechanical eillciency.

I Other objects and advantages will app ar from the following description of an embodiment of the invention shown somewhat diagrammatically in the accompanying drawings in which the views are as follows:

Fig. l. is a sectional plan view of a Pump in which the invention is embodied, the view being taken on the line |l of Fig. 2.

Fig. 2 is a transverse section taken'on the irregular line 2-.-2 of Fig. 1.

Fig. 3 is a'transverse section taken on a line 3-4 of Fig. 1.

Fig.4 is a section through one of the two valves which control the flow of liquid to and from the cylinders, the view being taken on the line 4-4 of Fig. 3.

Fig. 5 is a section through the same valve taken on the irregular line 5'-5 of Fig. 4.

Fig. 6 is in part a force diagram and in part a vertical section through the operating mechanism of the pump, the section being taken on the line 6-4 of Fig. 3 and the cylinder barrel being rotated slightly from the position shown in Fig. 1.

' Fig. "7 is a forcediagram and represents an end view of the cylinder barrel and the thrust I members.

The pump chosen for illustration has its pistons and cylinders arranged in a cylinder barrel i and divided into two sets each of which consists of a ventionhas the advantage that it may be smaller and lighter than a prior machine of the same type suitable number of pistons and cylinders depending upon the volumetric capacity of. the pump. As shown, two circumferential rows of radial cylinders 2 are formed in the front half of cylinder barrel I, a piston 3 is fitted in each cylinder 2; two circumferential rows of radial cylinders 4 are formed in the rear half of cylinder barrel 1 and a piston 5 is fitted in each cylinder 6. The total displacement of all of the pistons 5 is preferably the same as the total displacement of all of the pistons 3. Also, each cylinderl is preferably diametrically opposite a cylinder 2 but in a different plane.

Liquid flows to and from the cylinders through a plurality of axial channels 6 and I which extend inward from opposite ends of cylinder barrel i and each channel may connect with one or more cylinders. As shown, each channel 6' extends inward from the front end of cylinder barrel i into communication with a cylinder 2 in each of the two front rows, and each channel I. extends inward from the rear end of cylinder each of the two rear rows.

i 'a ica'ess 'of cylinder barrel I is effected by means ofa drive shaft I3 which is splined thereto and extends outward through block II in which it is rotatablysupported by a bearing I4.

Pistons 3 and are adapted to be reciprocated, respectively, by two thrust members I6 and I6 which encircle cylinder barrel I and-which have their axes offset from the cylinder barrel axis when the pump is pumping liquid. For the purpose of illustration, the pump has been shown as being of the rolling piston type disclosed 'in Patent No. 2,704,068. That is, the inner peripheral surface of each thrust member is inclined in opposite directions and the outer ends of the pistons are beveled so that each piston engages the inner surface of a thrust ring upon a single spot whichis offset far enough from the piston axis to cause the piston to rotate in its cylinder as it reciprocates therein.

4 posite directions simultaneouslyand the pump will deliver liquid in a direction and at a rate determined by the direction and extent of movement of lever 26.

In order to maintain the over all length of the pump at a minimum cylinder barrel I has been shown as having its" ends recessed and channels 6 and! terminating within the recesses. The

recessed end portions of cylinder barrel I are made fiat and smooth to form valve seats for two

identical valves

40 and 40 which cooperate with channels 6 and I to control the flow of liquid In order that thrust member's I5 and I6 may be rotated in unison with cylinder barrel, they are mounted, respectively, in two bearings I1 and I8 which have been shown as ball bearings. 'If the pump is to be of the constant displacement type, the outer races of bearings I1 and I8 are fixed in stationary positions within casings I0 but they have been shown as being fixed, respectively, within two slide blocks I9 and which may be shifted in opposite directions transversely of the cylinder barrel axis to vary pump displacement.

Slide block I9 is mounted between roller or ball bearings 2| and 22 which ride upon hearing surfaces arranged upon the upper and lower walls of easing I0 and which permit slide block I9 to befreely moved transversely of the cylinder barrel axis but restrain it from vertical movement. Slide block 20 is similarly mounted between bearings not shown. Slide blocks I9 and 26 are prevented from moving axially by casing I0 such as by having their adjacent faces in engagement witha spacer ring 23 and their outer faces in engagement, respectively, with opposed bearing

surfaces

24 and 25 formed on the inside of casing III.

Any suitable means may be employed to shift slide blocks I9 and 20. As shown, alever 26 has an actuator 21 formed upon its inner end and pivoted upon its center-line'to casing I II by a pin 28. Actuator 21 has two

slots

28 and 30 extending inward from its opposite ends in alignment with each other and with pin 28. One end of actuator 21 extends between two spaced apart lugs 3| which are fixed to or formed integral with slide blocks I 9, and the other end of actuator 21 extends between two spaced apart lugs 32 which are fixed to or formed integral with slide block 20. Two

pins

33 and 34 are fixed, respectively, in lugs 3| and 32 equidistant-from pine 28 to and from

cylinders

2 and 4. Valve 46 is are ranged between the front end of cylinder barrel I and distributing block II, and valve 40 is arranged between the rear end 'of cylinder barrel I and distributing block l2. Each valve hasbeen shown as an integral structure but it may be formed by separate pieces welded or otherwise fastened together.

Valve 46 is provided with a central opening of sumcient size to therethrough and to permit valve 40 to be properly adjusted to its seat on the end of cylinder barrel. I. The inner end or face of valve 40 has formed therein two diametrically opposed substantially crescent shaped ports 4I and 42 with which each channel 6 communicates alternately as cylinder barrel I rotates, the outer ends of channel 6 constituting cylinder ports which cooperate with valve ports 4I and 42 to control the flow of liquid to and from cylinders 2. all of the,

equal to or slightly less than the angular distance between adjacent ends ofvalve ports 4| and 42 so that, during rotation of cylinder barrel I, each channel 6 opens to one valve port substantially instantaneously after it moves out of communication withthe other valve port.

The means for connecting valve ports M and 42 to an external circuit and the means for holdand are closely fitted in

slots

29 and 30 respect v ively.

The arrangement is such that, when' lever 26 is in its neutral position, the axes of thrust members I5 and I6 coincide with the axis of cylinder barrel I and pump displacementis zero. When lever 26 is moved in one direction or the other from its neutral position, actuator 21 will shift slide blocks I9 and 20 the same distance in oping

valves

40 and 40 against the ends of cylinder barrel I may be similar to those shown in application Serial No. 485,279, filed May 1, 1943, to which reference may be had for ments. As shown, valve port 4I communicates with a chamber 43 which is formed within valve 40 and has two passages 44 leading therefrom through the rear face of valve 40. Also, valve port 42 communicates witha chamber 45 which is formed within valve 40 and has two passages 46 leading therefrom to the rear face of valve 40, only one passage 4-6 being shown.

Distributing block I I has been shown as having two hold-up motors 50 arranged therein above the horizontal center-line of valve 40 and two hold-up motors 5i arranged therein below the horizontal center-line of valve 40 but the number of hold-up motors may be varied.

Each passage 44 communicates with a cylinder 52 of a hold-up motor 50 and each passage 46.

communicates with a cylinder 53 of a hold-up I motor 5|. The two cylinders 52 are connected to each other by a passage 54 which extends outward through distributing block II for connection to one side of an external circuit, and two cylinpermit shaft I3 to pass freely.

specific arrange ders 53 are connected der and urged by a spring 51 against an annular sealing member 58 which is urged by. spring ll against the outer end of valve ll. the contacting surfaces of member 58 and valve 40 being ground flat and the contacting surfaces of plston II and member 58 being ground spherical to provide self aligning liquid tight seals .therebetween.

vide communication between the passages in the valve and-the inner ends of the hold-up cylinders so that liquid may flow freely through the valve inward by thrust member is and will eject liquid from their cylinders. 4 into channel .58 and the pistons I in the upper half of cylinder barrel I will move progressively outward and draw liquid into their cylinders 4 from channel Bl. Since the axes of thrust. members. l5 and it are offset equal distances from the axis of cylinder barrel l, the stroke of each piston 3 will be the same as the stroke of the opposite piston 5.

When the liquid discharged by the pump meets a resistance, pump pressure rises and thrust mem- The openings through pistons 58 and member 5! prosee the distributing block .to and from the external circuit.

When the pump is idle,.valve is held to l ts seat solely by springs 51. butas soon as the pump starts to deliver liquid, the pressure created by the pumpfacts upon the outer ends of the hold-up pistons 56 in the pressure side of the circuit and" v causes those pistons to urge valve is toward its seat with a force proportional totpump pressure."

Valve may also be provided with auxiliary. hold-up motors and with balancing motors as shown in application Serial No.;485,2'79 but such motors have been omitted from the drawing-to avoid complicating the views. 1

Valve 40 1s identical to valve 40 and distributing block I! is-identical to distributing block it except that it has no central opening to accom- 'modate a shaft. Consequently. they have not been fully illustrated and a description thereof is deemed unnecessary, like parts and passages as far as shown being indicated by like reference numerals-with the exponent it added to the reference numerals applied to valve 40* and distributing block l2. Passage Si in block-ll andpassage 54 in block I! are connected to each bers ll and ll must force

pistons

3 and 5 inward against the pressurein their cylinders. Thrust member l5 transmits a pumping force F (Fig. 'I) through each piston 3 to the liquid in its cylinder and thrust member l6 transmits a pumping force F through each piston 5 to the liquid in its cylinder.

Each mice 1'' is equal in magnitude and opposite indirection to a force F but in the prior pumps of this general type all of the pumping forces are transmitted through the pistons in only one half of the cylinder barrel and the reaction to the pumping forces-must be provided solely by the cylinder barrel bearings which must be large enough to carry the heavy loads imposed thereon.

The resultant of forces F and the resultant of forces F oscillate from one side to the other of Y the vertical center-line of the cylinder barrel as other by a channel 59 which is also connected to a channel by means of which the machine may be connected to one side of an external circuit. Passage in block l l and passage I! in block l2 are connected to each other by a channel ii which is. also connected to a channel "by means of whiclithe machine maybeconnected to the other side of an external'circuit. Channels 5! and Cl have been shown as external channels but they may be arranged within the pump casing.

The pump may be supercharged by an auxiliary pump according to common practice but. since supercharging forms no part of the present inventioni'no auxiliary pump has been shown.

Operation When the axes of slide blocks is and a are offset from the cylinder barrel axis as shown and cylinder barrel I is rotated in a clockwise direction in respect to Figs. 2 and '1, the pistons I in the upper half of cylinder barrel I will be forced progressively inward by thrust member II and will elect liquid from their cylinders through the channels 6 connected thereto, valve port ll,

chamber 43, passages 44, hold-up motors II and passage 5i into channel 59. and the pistons I in the lower half .of cylinder barrel I will move pro gressively outward and draw liquid into their cylinders through the channels t t connected thereto, valve port 42, chamber 45, passages I, hold-up motors 5i and passage 55 from channel At the time, the pistons I in the lower half of cylinder barrel i will be forced progressively.

rotation of the cylinder-barrel causes successive channels I and I to move into and out of communication with the valve portsbut the average or mean position of each resultant is on the .vertical center-line of the cylinder barrel. For all practical purposestherefore, the pumping forces transmitted from thrust member l5 through pistons I may be considered as concentrated in a singledownward ,force Fl (Iig'. 7) located on the vertical center-line of the cylinder barrel, and the pumping forces transmitted from thrust member l8 through pistons 5 may be considered as concentrated in a single upward force FI located upon the vertical center-line of the cylinder barrel.

-Forces Fl and Fl are equal in magnitude and opposite in direction and would cancel each other if they were in the same plane but, as indicated in Fig. 6, they 'are offset from each other so that force Fl tends to impose a heavy downward load ,upon bearing I and force Fl tends to impose a heavy upward load upon bearing 9. That is, forces Fl and Fl tend-to rotate cylinder barrel I in a vertical-plane.

At the same time, pump pressure acts upon the pistons II of hold-up motors 50 (Figs. 3 and 4) in distributing block II and causes them to urge valve 40 toward cylinder barrel l. The forces exerted by these two pistons may be considered as being concentrated into asingle force F2 which is located midway between the two pistons and is therefore located upon the vertical center-line of cylinder barrel i above the horizontal center-line thereof. Force F2 is at all times proportional to force Fl for the reason that each of these forces is proportional to pump pressure. 4

Since valve All is identical to valve 40 and since the hold-up motors in distributing block I! are identical to and function in the same manner as the hold-up motors in distributing block II, the hold-up motors in distributing block l2 exert upon valve 40 a hold-up force F2 (Fig. 6) which is equal in magnitude and opposite in direction to below the horizontal center-line thereof the same distance that force F2 is spaoedthereabove.

As indicated in Fig. 8, hold-up forces F; and F1 act at right angles to pumping forces FI and Fl and resist rotationof cylinder barrel I in a vertical plane by forces!" and Fl. The resultant R of forces Fl and F2 passes through a point located upon the cylinder barrel axis midway between pistons I and 5 and the resultant R of forces FI and F2! passes through the same point.

Silice forc'es'Fi and Fl are equal in magnitude and oppositein direction and since forces F2 and F2 are also equal inmagnitude and opposite in direction, resultants R and R are tude and opposite in direction so that, theoretically, no pumping force is transmitted to the cylinder barrel bearings which, theoretically, need to be only large enough to carry theweig-ht of thecylinder barrel. The cylinder barrel bearing losses are thus. very small'and the small size of the cylinder barrel bearings make possible the production of a pump which is considerably-smaller and lighter than the prior; pumps of the same generaltype and capacity.

The machine embodying the invention has been described as a pump but. the machine will function as a motor when supplied with motive liquid equal in magni-' the cylinder bani-cl axis, two valves arranged upon opposite ends of said cylinder barrel to control the flow ozliquid to and from said cylinders, each valve having a high pressure port and a low pressure port with which each channel in the adjacent end of said cylinder barrel registers alternately as said cylinder barrel rotates, means for urging each of said valves against said cylinder barrel with a force which varies in accordance with variations in the pressure in its high pressure port, and means, for shifting said thrust members in opposite directions placement of said machine.

3. In a pump having a rotatable cylinder barrel andplstons and cylinders extending inward from the circumferential periphery of said cylinder barrel, the combination of two valves arranged uponppposite ends or said cylinder barrel for controlling the flow of liquid to and from said cylinders, two thrust members arranged around said cylinder barrel to engage the outer ends of said pistons and having their axes ofiset in oppo-.

site directions from the axis of said cylinder barrel so that during rotation of said cylinder barrel pistons at opposite sldes'of the cylinder barrel axis are moved inward simultaneously by pumping forces transmitted thereto from said and the term "pump" as used in the specification and claims is intended to mean a hydrodynamic machine regardless of whether the machine functions as a pump or as a motor.

The invention herein set forth is susceptible of various modifications withoutdeparting from the scope of the invention which is hereby claimed as follows:

1. In a hydrodynamic machine, they combination of a rotatable cylinder barrel having a first and a second set of cylinders extending inward from its circumferential periphery and a first trol the flow of liquid to and from. said-cylinders, 7

each valve having a highpressure port and a low pressure port with which each channel in the adjacent end of said cylinder barrel registersalternately as said cylinder barrel rotates, and

means for urging each of said valves against said cylinder barrel. with a force which varies inaccordance with variations in the pressure in its high pressure port.

2. In a hydrodynamic machine, the combina tion of a rotatable cylinder barrel having a first anda second set of cylinders extending inward from its circumferential periphery'and a first and a second set of channels extending inward from thrust members and the resultants of all pumping forces tend to rotatesaid cylinder barrel in the plane of said resultants, and means for applying to each valve a hold-up force upon that side of the cylinder barrel axis upon which pumping forces are applied to the pistons adjacent to that valve so that the hold-up forces applied to the two valves tend to counteract the rotative effect of the pumping forces. 1

4. In a pump having a rotatable cylinder barrel and pistons and cylinders extending inward from the circumferential periphery of said cylinder barrel, the combination of two valves arranged upon opposite ends of said cylinder barrel for controlling the flow of liquid to and from said cylinders, two thrust members arranged around said cylinder barrel to engage the outer ends of said pistons and having their axes offset in opposite directions from the axis of said cylinder barrel so that during rotation of said cylinder barrel pistons at opposite sides of the cylinder' barrel axis are'moved inward simultaneously by pumping forces transmitted thereto from said thrust members and the resultants of all pumping forces tend to rotate said cylinder barrel in the plane of said resultants, means for applying to each valve a hold-up force upon thatslde of the cylinder barrel axis upon which pumping forces are applied to the pistons adjacent to that valve so that the hold-up forces applied to the two valves tend to counteract the rotative effect of the pumplng'forces, and means for shifting said thrust members in opposite directions to vary the displacement of said pump,

5.- In a pump having a rotatable cylinder barrel and pistons and cylinders extending inward from the circumferential periphery of said cylinder barrel, the combination of two valves arranged upon opposite ends of said cylinder barrel for its opposite ends into communication with the cylinders of said first and second sets respectively, a piston arranged in each cylinder, a thrust member extending around said cylinder barrel and engaging the outer ends of the pistons of one set, a second thrust member extending around said cylinder barrel and engaging the outer ends of" the pistons or the other set, the axes of said-thrust members being onset in opposite directions from controlling the flow of liquid to and from said cylinders, two thrust members arranged around said cylinder barrel to engage the outer ends of said pistons and having their axes onset in opposite directions from the axis of said cylinder barrel so that during rotation of said cylinder barrel pistons at opposite sides of the cylinder barrel axis are moved inward simultaneously by pumpingforces transmitted thereto from said thrust to vary the an by liquid discharged by said pump for applying to each valve a hold-up force upon that side of the cylinder barrel axis upon which pumping forces are applied to the pistons adjacent to'that valve so that the hold-up forces applied to the two valves tend to counteract the rotative effect of the pumping forces.

6. In a pump having a rotatable cylinder barrel and pistons and cylinders extendinginward from the circumferential periphery of said cylinderbarrel, the combination of two valves arranged upon opposite ends of said cylinder barrelrfor controlling the flow of liquid to andfrom said cylinders, two thrust members arranged around said cylinder barrel to engage the outer ends of said pistons and having their axes oifset in opposite directions from the axis of said cylinder barrel so that during rotation of said cylinder barrel pistons at opposite sides of the cylinder barrel axis are moved inward simultaneously by pumping forces transmitted thereto from said thrust members and the resultants of all pumping forces tend to rotate said cylinder barrel in the plane of said resultants, hold-up motors energized by liquid discharged by said pump for applying to each valve a hold-up force upon that side of the cylinder barrel axis upon which pumping forces are applied to the pistons adjacent to that valve so that the hold-up forces applied to the two valves tend to counteract the rotative effect of the pumping forces, and means for shifting said thrust members in opposite directions simultaneously to vary the displacement of said pump.

7 7. In a pump, the combination of a rotatable cylinder barrel having a first set of substantially radial cylinders arranged adjacent one end thereof and a second set of substantially radial cylinders arranged adjacent the other end thereof and fluid channels extending inward from each of its ends into communication with the cylinders of the adjacent set, a piston fitted in each cylinder, a valve arranged upon each end of said cylinder barrel to control the flow of liquid to and from the cylinders of the adjacent set and having a high pressure port and a low pressure port with which each channel in the adjacent end of said'cylinder barrel registers alternatively as said cylinder barrel rotates, a thrust member extending around said cylinder barrel to engage the outer ends of the pistons in the first set of cylinders, a second thrust member extending around said cylinder barrel to engage the outer ends of the pistons in the second set of cylinders, the axes of said thrust members being offset in opposite directions from the cylinder barrel axis so that during rotation of said cylinder barrel pistons at opposite sides of and adjacent opposite ends of said cylinder barrel are moved inward simultaneously by pumping forces transmitted thereto from said thrust members and the resultants of all of said pumping forces tend to rotate said cylinder barrel in the plane of said resultants, and means for applying to each valve a hold-up force upon that side of the cylinder barrel axis upon which pumping forces are applied to the pistons adjacent to that valve so that the hold-up forces applied to the two valves tend to counteract the rotative'eiIect of the pumping forces.

8. In a pump, the combination of a rotatable cylinder barrel having a first set of substantially radial cylinders arranged adjacent one end thereof and a second set of substantially radial cylinders arranged adjacent the other end thereof and fluid channels extending inward from eachof its ends into communication with the cylinders .of the adjacent set, a piston fitted in each cylin der, a valve arranged upon'each end of said.

' as said cylinder barrel rotates, a thrust member extending around said cylinder barrel to engage the outer ends of i the pistons in the first set of cylinders, a, second thrust member extending around said cylinder barrel to engage the outer ends of the pistons in the second set of cylinders, the axes of said thrust members beingoffset in opposite directions from the cylinder barrel axis,

so that during rotation of said cylinder barrel pistons at opposite sides of and adjacent opposite ends of said cylinder barrel are moved inward simultaneously by pumping forces transmitted thereto from said thrust members and the resultants of all of said pumping forces tend to rotate said cylinder barrel in the plane of said resultants, means for applying to each valve a holdr-up'force upon that side of the cylinder barrel axis upon which pumping forces are applied to the pistons adjacent to that valve so that the hold-up forces applied to the two valves tend to counteract the rotative effect of the pumping forces, and means for shifting said thrust members in opposite directions to vary the displacement of said pump.

9. In a pump, the combination of a rotatable cylinder barrel having a first set of substantially radial cylinders arranged adjacent one end thereof and a second set of substantially radial cylinders arranged adjacent the other end thereof and fluid channels extending inward from each of its ends into communication with the cylinders of the adjacent set, a piston fitted in each cylinder, a valve arranged upon each end of said cylinder barrel to control the flow of liquid to and from the cylinders of the adjacent set and having a high pressure port and a' low pressure port with which each channel in the adjacent end of said cylinder barrel registers alternately as said cylinder barrel rotates, a thrust member extending around said cylinder barrel to engage the outer ends of the pistons in the first set of cylinders, a second thrust member extending around said cylinder barrel to engage the outer ends of the pistons in the second set of cylinders, the axes of said thrust members being offset in opposite directions from the cylinder barrel axis so that during rotation of said cylinder barrel pistons at opposite sides of and adjacent opposite endsof said cylinder barrel are moved inward simultaneously by pumping forces transmitted counteracting at least in part the rotative effect of said pumping forces 10. In a pump, the combination of a rotatable cylinder barrel having a first set of substantially radial cylinders arranged adjacent one end thereof and a second set of substantially radial cylinders arranged adjacent the other end thereof and fluid channels extending inward from each of its ends into communication with the cylinders of the adjacent set, a piston fitted in each cylinder, a valve arranged upon each end of said cylinder barrel to control the flow of liquid to and 1 said cylinder barrel rotates, a thrust member extending around said cylinder barrel to engage the outer ends of the pistons in the first set of cylinders, asecond thrust member extending around said cylinder barrel to engage the outer endsof the pistons in the second set of cylinders, the axes of said thrust members being offset in opposite directions from the cylinder barrel axis so that during rotationwof said cylinder barrel pistons at opposite sides 0! and adjacent opposite ends of said cylinder barrel are moved inward simultaneously by pumping forces transmitted thereto from said thrust members and the resultants of all of said pumping forces tend to rotate said cylinder barrelin the plane of said resultants, hydraulic means operated at a pressure proportional to the pressure created by said inward moving pistons for holding said valves against the ends of said cylinder barrel and for counteracting at least in part the rotative eflect of said pumping forces, and means for shifting said thrust members in opposite directions to u vary the displacement ofsaid pump.

11. In a pump, the combination of a rotatable cylinder barrel having a first set of substantially radial cylinders arranged adjacent one end thereof and a second set of substantially radial cylinders arranged adjacent the other end thereof and fluid channels extending inward from each of its ends into communication with the cylinders of the adjacent set, a piston fitted in each cylinder, a valve arranged upon each end of said cylinder barrel to control the flow of liquid to and from the cylinders of the adjacent set and having a high pressure port and a low pressure ,xportwith which each channel in the adjacent end of said cylinder barrel registers alternately as said cylinder barrel rotates, a thrust member extendingaround said cylinder barrel to engage the outer ends of the pistons in the first set of.

, cylinders, a second thrust member extending around saidcylinder barrel to engage the outer ends of the pistons in the second set of cylinders,

the axes a: said thrust members being ofl'set in opposite directions from the cylinder barrel axis so that during rotation of said cylinder barrel pistons at opposite sides of and adjacent opposite ends of said cylinder barrel are moved inward simultaneously by pumping forces transmitted thereto from said thrust members and the reradial cylinders arranged adjacent one end thereof and a second set of substantially radial cylinders arranged adjacent the other end thereof and fluid channels extending inward from each of its ends into communication with the cylinders of the adjacent set, a piston fitted in each cylinder, a valve arranged upon each end of said cylinder barrel to control the flow of liquid to and from the cylinders of the adjacent set and having a high pressure port and a low pressure port with which each channel in the adjacent end of said cylinder barrel registers alternately as said cylinder barrel rotates, a thrust member extending around said cylinder barrel to engage the outer ends of the pistons in the first set of cylinders, a second thrust member extending around said cylinder barrel to engage the outer ends of the pistons in the second set of cylinders, the axes of said thrust members being offset in opposite directions from the c; nder barrel axis so that during rotation of said cylinder barrel pistons at oppositesides of and adjacent opposite ends of said cylinder barrel are moved inward simultaneously by pumping forces transmitted thereto from said thrust members and the resultants of all of said pumping. forces tend to rotate said cylinderbarrel in the plane of said resultants, hydraulic hold-up motors engaging said valves and communicating with said high pressure ports for holding said valves against the ends of said cylinder barrel and for counteracting at least in part the rotative effect of said pumping forces, and means for shifting said thrust members in opposite directions to vary the displacement of said pump.

WALTER FERRIS.

JAMES K. DOUGLAS.

REFERENCES CITED I The following references are of record in the file of this patent:

UNITED STATES PATENTS