US1925378A

US1925378A - Pump

Info

Publication number: US1925378A
Application number: US526891A
Authority: US
Inventors: John P Ferris; Ferris Walter
Original assignee: Oilgear Co
Current assignee: Oilgear Co
Priority date: 1931-04-01
Filing date: 1931-04-01
Publication date: 1933-09-05
Anticipated expiration: 1950-09-05

Description

Sept 5,

J' P' FERRIS ELT-AL PUMP WALTER FERR@ J. P. Fr-:'RRls ET Al.- .1,925,378

PUMP

Sept.v 5', 1933.

3 Sheets-Sheet 2 Filed April 1, 1931 Jul-IN FERRIS.

- WALTER F'EHRIS.

Sept- `5, 1933- v J. F. FERRls Er A1. 1,925,378

PUMP

Filed April 1, .19:51 ls sheets-sheet z' Patented Sept. 5, 1933 N PUMP u John P. Ferris, Whitefish Bay, and Walter Ferris, Milwaukee, Wis., assignors to The Oilgear Company, Milwaukee, Wis., a corporation of Wiscousin Application April-1,1931. Serial No. 526,891 zo claims. (oi. 10s-162) This invention relates to pumps. barrel having an axial bore, the pintle extends The pump to which the invention applies in into the bore and is supported in part by the particular' has its rotor journaled upon a pintle wall thereof, and a exible connection retains the and provided with cylinders which are parallel pintle in position and allows it to seat itself Within 5 to the axis thereof, pistons fitted in the cylinders the bore.

and reciprocated therein by engagement with a According to the invention in another aspect, thrust member which isinclined to the axis of the pintle and the bore of the cylinder barrel rotation, and ports and passageways in the pintle are tapered and the pintle is urged into the bore through which liquid is delivered to the cylinders of the cylinder barrel by a constant force and and discharged therefrom. also urged into the bore of the cylinder barrel 65 Liquid escapes from between the complemenand toward the pressure side of the pump by a tary surfaces of the pintle and cylinder barrel force which is proportional to pump pressure.

when the pump is in operation, and this volume A pump embodying the invention is illustrated of escaping liquid, which is generally designated in the accompanying drawings in which the views as the slip of the pump, increasesy as the presare as follows: 70 sure created by the pump increases. Fig. 1 is a sectional plan View taken on the line The volume of liquid escaping from between 1-1 of Fig. 3. p

the pintle and the cylinder barrel' at any given Fig. 2 is a longitudinal vertical section taken pressure varies according to the variation in on the line 2--2 of Fig. 3.

clearance between the coacting surfaces thereof Fig. 3 is a transverse vertical section taken on. 75 and variation in this clearance is caused by wear the line 3-3 of Fig. 2.

on the coacting surfaces and by inaccurate aline- Fig. 4 is a diagram of th hydraulic circuit.

ment of the parts due to compounding slight The pump has its mechanism enclosed within a ,manufacturing errors which are difficult to avoid casing 1 which is closed at its front end by a 80 o inthe manufacture of the pump. removable head 2 and at its rear end by a re- An object`of this invention is to provide a pump movable head 3. of this character in which the pintle is free to The casing 1 has a rotatable cylinder barrel adjust itself within the cylinder barrel. supported therein by an anti-friction thrust Another object is to compensate for the lateral bearing 5 which is carried by the casing 1 and thrust of the pressure liquid upon the pintle. has the rear face of its outer ring in engagement 85 Another object is to reduce the slip of the pump with a llange 6 formed on the casing 1 and the to a minimum by automatically maintaining the iront face of its inner ring in engagement with oil film between the cylinder barrel and the pintle a flange '1 formed on the cylinder barrel ll. at the minimum thickness at which the parts will The cylinder barrel 4 isrotated by a driving 90 o run without seizing or binding. shaft 8 which has its front end extended through A nother object is to maintain the slip of the the front head 2 and supported therein by an pump at a substantially constant minimum volanti-friction thrust bearing 9. urne throughout a wide variation in pump pres- The bearings 5 and 9 rotatably support the sures. cylinder barrel 4 and the shaft 8 and hold the Another object is to urge the coacting surfaces same against axial movement during rotation of the cylinder barrel and the pintle toward each thereof. other by a force which is proportional to the The rear end of the shaft 8 is rigidly secured pressure Created by the pump. within a bore 10 which is formed axially in the Another object is to urge the coacting surfaces cylinder barrel 4 and has its rear part tapered of the cylinder barrel and the pintle toward each to receive the tapered front part of a pintle 11. 100 other by both a constant force and a force which 'The cylinder barrel 4 has a number of parallel is proportional to pump pressure. cylinders 12 formed therein around the bore lo oril Another object is to provide a pump which is and communicating at the inner or rear ends compact and sturdy. thereof with the tapered'part of the bore 10 105' I Another object is to provide a pump of this through ports 13 which register alternately with character which is eilicient in operation. a segmental intake port 14 and a segmental dis- Another object is to provide a pump which is charge port 15 formed in the tapered part of the easily and readily assembled and disassembled. pintle l1 diametrically opposite each other. According to the invention in one` of its aspects, The ports lll and l5 communicate, respective- 110 the pump has its cylinders arranged in a cylinder ly, with an intake passageway 16 and a discharge through the pintle 1'1 and then radially outward through a thrust block 18 which is secured to the rear part of the pintle 11 or formed integral therewith.

The thrust block 18 has an intake pipe 19 and a discharge pipe 20 connected thereto and communicating, respectively, with the passageways 16 and 17. Each of these pipes is preferably provided with a loop or bend -to permit deflection thereof and thus allow the pintle 1l to seat litself accurately in the tapered part of the bore 10.

The intake pipe 19 may be connected directly to a reservoir 21 containing a supply of liquid, such as oil, or it may be connected thereto through a gear pump 22 which supplies liquid under pressure to the cylinders 12, as shown diagrammatically in Fig. 4.

Each of the cylinders 12 has a piston 23 tted therein and urged outward or forward by a helical compression spring 24 which is arranged in the cylinder 12 between its inner or rear end and the piston 23.

The outer or front ends of the pistons 23 pro ject into counterbores 25 which are formed in the cylinder barrel 4 concentric to the cylinders 12.v

A plunger 26 is fitted in each counterbore 25 and has its rear end in engagement with the piston A23 and its front end protruding beyond the front end of the cylinder barrel 4.

The springs 24 urge the pistons 23 outward`or forward and hold the front ends of the plungers 26 against the inner ring of an anti-friction thrust bearing 27 carried by a cam plate 28 which is pivoted at its lower edge upon a pivot 29 secured in the casing 1.

The cam plate 28 is normally inclined to the axis of the pump and is held in adjusted positions by a lever 30 which is pivoted intermediate its ends upon a stationary pivot 31 and has its lower end in engagement with the front of the cam plate 28 at the upper edge thereof andits upper end in engagement with an adjusting screw 32 threaded through the rear wall of the front head 2.

The screw 32 may be ladvanced or retracted to swing-the lever 30 upon its pivot 31 and change the inclination of the cam plate 28 to thereby vary the stroke of the pump. l

When the pump is in operation, the cylinder barrel 4.and the shaft 8 are rotated in the direction of the arrows shown in the drawings, the pistons at the right of the vertical center line of Fig. 3 move outward or forward and' draw liquid into their cylnders through the intakeports and passageways, and the pistons upon the other side of the center line move inward or rearward and force liquid from their cylinders through the discharge port and passageway into the discharge pipe 20. l

The pistons are forced inward by the outer end of the plungers 26 moving along the inclined face of the cam plate 28 and are moved outward by the springs 24 and, if the gear pump\ 22 is employed, the pistons are moved outward by the pressure of the `liquid delivered thereby. 'I'he spring 24 may be omitted when liquid is delivered under pressure to the cylinders 12.

Due to the inclination of the cam plate 28, there isa slight relative radial movement between the `axis thereof and the axis of the pistons 23 and,

if the ends of the pistons abutted the inner ring of the .bearing 27, the friction produced by this movement would create lateral thrusts upon the 1,925,378 passageway 17 extending rearward therefrom pistons which would cause undue wear upon the cylinder walls and result in leakage of the pump.

Consequently, the plungers 26 are interposed between the pistons 23 and the thrust bearing 27 to transmit these lateral thrusts to the walls of the counterbores 25.

In order that hydraulic pressure may not be created in the counterbores 25 by liquid seeping from the cylinders 12, each counterbore has a drain holev 33 formed in its side walls through which liquid is discharged into the casing 1.

When the pump is in operation, the pressure created in the cylinders 12 on the pressure side of the pump is transmitted to that part of the lm of liquid which is on the pressure side of the pump between the pintle and the cylinder barrel.

'I'he longitudinal component of this force urges the pinle 11 rearward and tends to force it out vof the bore 10, and the lateral component of this force urges the pintle toward the intake side of the pump and tends to make it bear more heavily upon that side of the bore 10 than upon the opposite side thereof.

In order to reduce the force exerted upon the pintle 11 by the pressure liquid, the area upon which this liquid may act is reduced by two circumferential grooves 34 and 35, which are formed in theperiphery of the pintle on opposite sides of the ports 14 and l5, and by axial grooves 36 and 37 which lead, respectively, from the grooves 34 and 35 to the ends of .the tapered part of the pintle.

These grooves also assist in maintaining a lubricating film of liquid over the entire area of the complementary surfaces of the pintle and the cylinder barrel.

The liquid collected by the grooves 35 escapes through the grooves 37 into the casing 1, the liquid collected by the groves 34 escapes through the grooves 36 into the bore 10 and thence through a drain hole 38 into the casing 1, and the liquid collected in the casing 1 is returned to the Areservoir 21 through a drain pipe 39.

The pintle 11 is urged rinto the bore 10 by' a helical Icompression spring 40 arranged between its rear end and an adjusting screw 41 which is threaded through the rear head- 3 and held in adjusted positions by a lock nut 42.

. The spring 40 exerts a constant force upon the pintle 11 suicient to hold it to its lseat in the bore 10 until the pressure created by the pump has risen above a predetermined minimum.

The pintle l1 is also urged into the bore 10 and toward the pressure side of the pump by a piston 43 which exerts a force thereon proportional to pump pressure.

The piston 43 is fitted in a cylinder y44 which is arranged in the casing 1 at an angle to the' The outer end of the piston- 43 acts upon the Jthrust block 18 through an arm 46 thereof which is arranged at an angle to the axis of the pump and is preferably provided with a notch 47 which 'prevents the thrust4 block and the pintle from revolving, said notch also having a bearing ball 48 arranged therein to receive the thrust of the piston 43.

The ball 48 is held in position by two springs 49 and allows the arm 47 to move without putting an appreciable amount of lateral strain upon the piston 43, and the piston 43 is held in contact therewith successively as at all times with the ball 48 by a light spring 50 which is arranged in the cylinder 44.

When the pump is in operation, the spring 40 initially holds the pintle 1l to its seat so that the outward moving pistons 23 may draw liquid into their cylinders from the intake passageway 16 and the inward moving pistons 23 may expel liquid from their cylinders into the discharge passageway 17. t l

The discharge liquid flows into the discharge pipe 20 and then through the pipe 45 into the cylinder 44 .and, when the pump developspressure in the discharge pipe, the piston 43 is subjected to'this pressure and exerts a force proportional topump pressure upon the pintle 11 through the thrust block 18 and its arm 46.

The cylinder 44 is preferably of such size and arranged at such an angle to the axis of the pump that the lateral component of the force exerted by the piston' 43 upon the pintle l1 is somewhat in excess of the lateral component of theforce exerted thereon by the pressure liquid, and the axial component of the force exerted by the Ipiston 43 upon the pintle 11 exceeds the axial force exerted thereon by the pressure liquid.

The initial force exerted upon the pintle 1ly by the spring 40 is high enough to maintain sulcient surface pressure upon the lubricating film between the pintle and the cylinder barrel to keep the slip of the pump at a negligible minimum at low pressures but, with any given thickness of lubricating film, the slip of a pump would increase as the pump pressure increases were it not for the piston 43 and the cylinder 44.

Therefore, the cylinder 44 is so proportioned and arranged that the force exerted by the piston 43 upon the pintle l1 to is greater than the force which tends to urge it away from its seat in order to decrease the clearance between the coacting surfaces of the pintle and the cylinder barrel as the pump pressure rises and thereby maintain the slip of the pump at a substantially constant negligible volume throughout its operating range of pressures.

The invention herein set forth is' susceptible of various modifications without departing from the scope thereof as hereafter claimed.

Theinvention is hereby claimed as follows:

1. A pump, comprising a casing, a rotatable cylinder barrel journaled in said casing and having an axial bore and cylinders arranged parallel to said bore around the same and provided with ports communicating with said bore, means for rotating said cylinder barrel, pistons arranged in said cylinders, means for reciprocating said pistons as said cylinder barrel rotates, a pintle extending a substantial distance into said bore to be supported thereby and free from said casing to permit it to move laterally and seat itself in said bore and having intake and discharge passageways for the passage of liquid between said cylinders and the outsideof said cylinder barrel and intake and discharge ports communicating with said passageways and arranged in radial alinement with said cylinder ports to register said cylinder barrel rotates, and flexible means in position and allowing it to float substantially free within said bore.

2. A pump, comprising a casing, a rotatable cylinder barrel journaled in said casing and having a tapered axial bore and cylinders arranged parallel to the axis of said bore around the same and provided with ports communicating with said bore, means for rotating said cylinder barrel, pisforce it against its seat' for holding said pintle tons arranged in said cylinders, means for reciprocating said pistons as said cylinder barrel rotates, a tapered pintle extending a substantial distance into said bore to be supported thereby and free from said casing to permit it'to move laterally and seat itself in said bore and having .intake and discharge passageways for the passage of liquid between said cylinders and the outside of said cylinder barrel and intake and discharge ports communicating with said passageways and arranged in radial alinementl with said cylinder ports to register therewith successively as said cylinder barrel rotates, and flexible means for holding said pintle in position and allowing it to float substantially free within said bore.

3. A pump, comprising ak casing, a rotatable cylinder barrel journaled in said casing and having a tapered axial bore and cylinders arranged around said bore parallel to the axis thereof and provided with ports communicating with said bore, means for rotating said cylinder barrels, pistons arranged in said cylinders, means for reciprocating said pistons as said cylinder barrel rotates, a tapered pintle extending a substantial distance 4into said bore to be supported thereby and free from said casing to permit `it to move laterally and seat itself in said bore and having intake and discharge passageways for the passage of liquid between said cylinders and the outside of saidv cylinder barrel and intake and dis-.

charge ports communicating with said passageways and arranged in radial alinement with said cylinder ports to register therewith successively as said cylinder barrel rotates, a spring for holding said pintle in position and allowing it to float substantially free within said bore, and flexible pipes connected to said pintle for connecting said pump into a hydraulic circuit.

4.,A pump, cylinder barrel journaled in said casing and having a tapered axial bore and cylinders arranged around said bore parallel to the axis thereof and provided t,with ports communicating with said bore, means for rotating said cylinder barrel, pistons arranged in said cylinders, means for reciprocating said vpistons as said cylinder barrel rotates, a tapered pintle arranged in said bore and having longitudinal intake and discharge passageways for the passage of liquid between said cylinders and the outside of "said cylinder barrel and transverse intakel and discharge ports communicating with said passageways and arranged in the plane of said cylinder ports to register therewith successively as said cylinder barrel rotates, flexible means for holding said pintle in position and allowing it to float substantially free within said bore, and means independent of said flexible means for exerting upon said pintle lateral and axial forces counter to the corresponding forces exerted thereon by the pressure liquid.

5. A pump, comprising a casing, a rotatable cylinder barrel journaled in said casing and having a tapered axial bore and cylinders arranged around said bore parallel to the axis thereof and provided with ports communicating with said bore, means for rotating said cylinder barrel, pistons arranged in said cylinders, means for reciprocating said pistons as said cylinder barrel rotates, a tapered pintle arranged in said bore and having longitudinal intake and discharge passageways for the passage of liquid between said cylinders and the outside of said cylinder barrel and transverse intake and discharge ports communicating with said passageways and arranged in the plane of said cylinder ports to register therewith successivelyl as said cylinder barrel rotates,y a spring for holding said pintle in position and allowing it to iloat substantially free forces counter to the corresponding forces exerted thereon by the pressure liquid.

6. A pump, comprising a casing, a rotatable cylinderbarrel journaled iny said casing and having a tapered axial bore and cylinders arranged around said bore parallel to the axis thereof and ciprocating rotates, a tapered pintle arranged in said bore 7. A pump, comprising a casing, a rotatable cylinder barrel journaled in said casing and having a tapered bore and cylinders arranged around said bore parallel to the axis thereof and provided with ports communicating with said bore, means for rotating said cylinder barrel, pistons arranged in said cylinders, means for reciprocating said pistons as said cylinder barrel rotates, a tapered pintle arranged in said bore and having longitudinal intake and discharge passageways for the passage of liquid between said cylinders and the outside of said cylinder barrel and transverse intake and discharge ports communicating with said passageways and arranged in the plane of said cylinder ports to register therewith successively as said cylinder barrel rotates, a spring counter to the corresponding forces exerted thereon by the pressure liquid.

-8. A pump,v comprising a casing, a rotatable cylinder barrel journaled in said casing and having a tapered bore and cylinders arranged around said bore parallel to the axis thereof and proel vided with ports communicating with said bore,

means for rotating said cylinder barrel, pistons lible means for holding said pintle in position and allowing it 'to float substantially free within i reciprocating bore, means said bore, and hydraulic means independent of said flexible means for exerting upon said pintle lateral and axial forces proportional to pump pressure and counter to exerted thereon by the pressure liquid.

9. A pump, comprising a casing, a rotatable journaled in said casing and hav- Y ing a tapered bore and cylinders arranged around said bore parallel to the axis thereof and provided with ports communicating with said bore,

a spring for-holding saidpintle in position and allowing it to float substantially free within said bore, flexible pipes connected to said pintle for said pump into a hydraulic circuit,

forces proportional to pump pressure and counter to the corresponding forces exerted thereon by the pressure liquid.

10. A pump, comprising a casing, a rotatable cylinder barrel journaled in said casing and having a tapered axial bore and cylinders arranged around said bore parallel to the axis thereof and provided with ports communicating with said bore, means for rotating said cylinder barrel, pistons arranged in said cylinders, means for said pistons as said cylinder barrel rotates, a tapered pintle arranged in said bore and having intake and discharge passageways and intake and discharge ports communicating with said passageways and arranged in the plane of said cylinder ports to register therewith successively as said cylinder barrel rotates, a cylinder carried by saidvcasing and having its axis arranged at an angle to the axis of said pintle, a piston fitted in said cylinder for exerting a force upon said pintle, and means for directing liquid from the pressure side of said pump into said cylinder to advance said piston and cause it to exert upon said pintle a force having lateral and axial components counter to the forces exerted upon said pintle by the pressure liquid.

11. A pump, comprising a casing, a rotatable cylinder barrel journaled in said casing and having a tapered axial bore and cylinders arranged around said bore parallel to the axis thereof and provided with ports communicating with said for rotating said cylinder barrel, pistons arranged in said cylinders, means for reciprocating said pistons as said cylinder barrel rotates, atapered pintle arranged in said bore and having intake and discharge passageways and intake and discharge ports communicating with said passageways and arranged in the plane of said cylinder ports to register therewith successively as said cylinder barrel rotates, a thrust block carried by said pintle, a cylinder carried by said casing and having its axis arranged at an angle to the axis of said pintle, a piston fitted in said cylinder for exerting a force upon said thrust block, and means for directing liquid from the of said pump into said cylinder to advance said'piston and cause it to exert upon said thrust block a force having lateral and axial the corresponding forces components counter to the forces exerted upon said pintle by the pressure liquid.

12. A pump, comprising a casing, a rotatable cylinder barrel journaled in said casing and having a tapered axial bore and cylinders arranged around said bore parallel to the axis thereof and provided with ports communicating with said bore, means for rotating said cylinder barrel, pistons arranged in said cylinders, means for reciprocating said pistons as said cylinder barrel rotates, a tapered pintle arranged in said bore and having intake and discharge passageways and intake and discharge ports communicating with said passageways and arranged in the plane of said cylinder ports to register therewith successively as said cylinder barrel rotates, a spring urging said pintle into said bore, flexible pipes connected to said pintle for connecting said pump into a hydraulic circuit, a cylinder carried by said casing and having its axis arranged at an angle to the axis of said pintle, a piston tted in said cylinder for exerting a force upon said pintle, and means for directing liquid from the pressure side of said pump into said cylinder to advance said piston and cause it to exert upon said pintle a force having lateral and axial components counter to the forces exerted upon said pintle by the pressure liquid.

13. A pump, comprising a casing, a rotatable cylinder barrel journaled in said casing and having a tapered axial bore and cylinders arranged around' said bore parallel to the axis thereof and provided with ports communicating with said bore, means for rotating said cylinder barrel, pistons arranged in said cylinders, means for reciprocating said pistons as said cylinder barrel rotates, a tapered pintle arranged in said bore and having intake and discharge passageways and intake and discharge ports communicating with said passageways and arranged in the plane of said cylinder ports to register therewith successively as said cylinder barrel rotates, a spring urging said pintle into said bore, flexible pipes connected to said pintle for connecting said pump into a hydraulic circuit, a thrust block carried by said pintle, a cylinder carried by said casing and having itsy axis arranged at an angle to the axis of said pintle, a piston fitted in said cylinder for exerting a force upon said thrust block, and means for directing liquid from the pressure side of said pump into said cylinder to advance said piston and cause it to exert upon said thrust block aforce having lateral and axial components counter to the forces exerted upon said pintle by the pressure liquid.

14. A pump, comprising a casing, a rotatable cylinder barrel journaled in said casing and having a tapered axial bore and cylinders arranged around said bore parallel to the axis thereof and provided with ports communicating with said bore,- means for rotating said cylinder barrel, pistons arranged in said cylinders, means for reciprocating said` pistons as said cylinder barrel rotates, a tapered pintle arranged in said bore and having intake and discharge passageways and intake and discharge ports communicating with said passageways and arranged in the plane of said cylinder ports to register therewith successively as said cylinder barrel rotates, a thrust block carried by said pintle and having a bearing-ball arranged therein, a cylinder carried by said casing and having its axis arranged at an angle to the axis of said pintle, a piston fitted in said cylinder for engaging said bearing ball, and means for directing liquid from the pressure side of said pump into said cylinder to advance said piston and cause it to exert upon said bearing ball a force having lateral and axial components counter to the forces exerted upon said pintle by the pressure liquid.

15. A pump, comprising a casing, a rotatable cylinder barrel journaled in said casing and having a tapered axial bore and cylinders arranged around said bore parallel to the axis thereof and provided with ports communicating with said bore, means for rotating said cylinder barrel, pistons arranged in said cylinders, means for reciprocating said pistons as said cylinder barrel rotates, a tapered pintle arranged in said bore and having intake and discharge passageways and intake and discharge ports communicating with said passageways and arranged in the plane of said cylinder ports to register therewith'successively as said cylinder barrel rotates, a spring ,urging said pintle into said bore, flexible pipes connected to said pintle for connecting said pump into a hydraulic circuit, a thrust block carried by said pintle and having abearing ball arranged therein, a cylinder carried by saidcasing and having `its axis arranged at an angle to the axis of said pintle, a piston tted in said cylinder for engaging said bearing ball, and means for directing liquid from the pressure side of said pump into saidcylinder to advance said piston and cause it to exert upon said bearing ball a force having lateral and axial components counter to the forces exerted upon said pintle by the pressure liquid.

16. A pump, comprising a casing, a rotatable cylinder barrel journaled in said casing and having a tapered axial bore and cylinders arranged around said bore parallel to the axis thereoi` and provided with ports communicating with said bore, a drive shaft journaled in said casing and connected to said cylinder barrel for rotating the4 same and supporting the front end thereof, pisto'ns arranged in said cylinders, means for reciprocating said pistons as said' cylinder barrel rotates, a tapered pintle extending 'a substantial distance into said bore to be supported thereby and free from said casing to permit it to move laterally and seat itself; within said bore and having intake and discharge passageways for the passage of liquid between said cylinders and the outside of said cylinder barrel and intake and discharge ports communicating with said passageways and arranged in radial alinement with said cylinder ports to register therewith successively as said cylinder barrel rotates, and means for holding said pintle in' position within said bore and allowing it to float substantially free therein.

17. A pump, comprising a casing, a rotatable cylinder barrel journaled in said casing and having a tapered axial bore and cylinders arranged around said bore parallel tothe axis thereof and provided with ports communicating with said bore, means for rotating said cylinder barrel, pistons fitted in said cylinders and urged outward, a swash plate for moving said pistons inward as said cylinder barrel rotates, a tapered pintle ex-..

tending a substantial distance into said bore to be supported thereby and free from said casing to permit it to move laterally and seat itself within said bore' and having intake and discharge passageways for the passage of liquid between said cylindersand the outside of said cylinder barrel and intake and discharge ports communicating with said passageways and arranged in radial alinement with said cylinder ports to regcylinder barrel provided with ward, a swash plate for -Ward as said cylinder barrel rotates, a tapered ister therewith successively as said cylinder barrel rotates, means for holding said pintle in position within said bore and allowing it to float substantially free therein, and flexible means for connecting said pintle into a hydraulic circuit.

18. A pump, comprising a casing, a rotatable cylinder barrel journaled in said casing and having a tapered axial bore and cylinders arranged around said bore parallel to the axis thereof and provided 'with ports communicating with said bore, means for rotating said cylinder barrel, pistons arranged in said cylinders, means for operating said pistons as said cylinder barrel rotates, plungers fitted in said cylinder barrel in engagement with said pistons for transmitting axial movement thereto from said piston operating means and preventing the transmission of lateral forces thereto from said piston operating means, a tapered pintle extending a substantial distance into said bore to be supported thereby and free from said casing to permit it to move laterally and seat itself within said. bore and having intake and discharge passageways for the passage of liquid between said cylinders arid the outside of said cylinder barrel and intake and discharge ports communicating withl said passageways and arranged in radial alinement with said cylinder ports to register therewith successively as said cylinder barrel rotates, and means for holding said pintle in position within said bore and allowing it to float substantially free therein.

19. A pump, comprising a casing, a rotatable journaled in said casing and having a tapered axial bore and cylinders arranged around said bore parallel to the axis thereof and ports communicating with said bore, a drive shaft journaled in said casing and connected to said cylinder barrel for rotating the same and supporting the front end thereof, pistons arranged in said cylinders. and urged outmoving said pistons inpintle extending a substantial distance into said municating with said bore to be supported thereby and free from ser@ casing to permit it to move laterally and seat itself within said bore and having intake and discharge passageways for the passage of liquidbetween said cylinders and. the outside of said cylinder barrel and intake and discharge ports communicating with said passageways and arranged in radial alinement with said cylinder ports to register therewith successively as said cylinder barrel rotates, means for holding said pintle in position Within said bore and allowing it to float substantially free therein, and flexible pipes connected to said pintle for connecting said pump into a hydraulic circuit.

20. A pump, comprising a casing, a rotatable cylinder barrel journaled in said casing and hav'- ing a tapered axial bore and cylinders arranged around said boreparallel to the axis thereof and provided with ports communicating with said bore, means for rotating said cylinder barrel, pistons fitted in said cylinders and urged outward, a swash plate for moving said pistons inward as said cylinder barrel rotates, plungers fitted in said cylinder barrel for transmittingaxial movement from said swash plate to said pistons and preventing the transmission of lateral forces from said swash plate to said pistons, a tapered pintle extending a substantial distance into said bore to be supported therebyand free from said casing to permit it to move laterally and seat itself within said bore and having intake and discharge passageways for the passage of liquid between said cylinders and the outside of said cylinder barrel and intake and discharge ports compassageways and arranged in radial alinement with said cylinder ports to register therewith successively as said cylinder barrel rotates, means for holding said pintle in position within said bore and allowing it to float substantially free therein, and liexible pipes connected to said pintle for connecting said pump into a hydraulic circuit.

JOHN P. FERRIS.

WALTER FERRIS.

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