US2612873A - Fluid power conversion apparatus - Google Patents
Fluid power conversion apparatus Download PDFInfo
- Publication number
- US2612873A US2612873A US659176A US65917646A US2612873A US 2612873 A US2612873 A US 2612873A US 659176 A US659176 A US 659176A US 65917646 A US65917646 A US 65917646A US 2612873 A US2612873 A US 2612873A
- Authority
- US
- United States
- Prior art keywords
- pressure
- rotor
- chamber
- ring
- motor
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
Images
Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16H—GEARING
- F16H39/00—Rotary fluid gearing using pumps and motors of the volumetric type, i.e. passing a predetermined volume of fluid per revolution
- F16H39/04—Rotary fluid gearing using pumps and motors of the volumetric type, i.e. passing a predetermined volume of fluid per revolution with liquid motor and pump combined in one unit
- F16H39/42—Rotary fluid gearing using pumps and motors of the volumetric type, i.e. passing a predetermined volume of fluid per revolution with liquid motor and pump combined in one unit pump and motor being of different types
Definitions
- This invention relatesto variable speed drives and particularly vto a drive employin a filliil pump and motor.
- the object of the invention istonrovide a d iv of this type which .will be simple, inexpens e a eificient and which will (provide 1 01:84 progressive, easily controlled variation in the sp ed 9 th motor. v
- Fig.2 is a front eleyational-view-with theiront plate omitted; r
- Fig. 3 is a vertical sectional view taken on-line 3-3 of Fig. 2;
- Fig. 4 is a perspective view in-detail of control valve on enlarged scale.
- Fig. 5 is a sectional view illustrating a-modified form of engagement between the plun gers and eccentric ring.
- the rotor comprises a shaft 6 (Fig. 3) vcarryingthe rotor head 1 and running in bearings-9 in the extension ll of the stator casing HL'carriedby the base 8, a cover l2 being fastened to the stator casing mas-shown.
- Radial cylinders 20 in the'rotor are fitted lwith piston plungers .2 I, each plunger comprisinga, cylindrical piston portion 22 and a rounded inner or.
- valve member 41 In the central position of valve member 41 (Fig. 2) both the pressure supply 53 and discharge 56 are out of communication with the passages l3 and to the motor, and then assuming that the pump 35 is running, its pressure fluid passes through passage 40 to'chamber 48, opening 49, bore 50 and by-pass 51 in the" valve and outlet passage 58 in the base structure to sump chamber 38 and back to the pump. No power is applied to drive the motor.
- valve member 41 When the motor is to be driven counterclockwise (Fig. 2) the valve member 41 is turned counter-clockwise by means on the outer end of the control shaft 59 extending forward from the member 41. The'flrst portion of this valve movement connects pressure chamber 53 to passage l3 and chamber l4 to supply fluid pressure to' the piston 2
- discharge'chamber 56 of the valve is connected to the passage l5 and'chamber 16 to permit outflow of fluid from the cylinders 20 on the right side of the [The initially applied pressure is low because of the bleeding of thefluid through by-passes 51, 58 into the sump, and as the valve 41 continues to turn, this by-pass relief is progressivelylchoked off until finally the valve opening 51 is entirely out of register with the matching drain' 58, whereupon full pressure is applied to the driving side of the motor and the exhaust side is connected freely to the discharge through 1 valve chamber 56 and passage 45 into the sump.
- the driving pressure will therefore depend on the position of the valve member 41 and for a given resistance to the motor drive the motor speed will vary with the .applied driving pressure.
- Control of the speed of the motor'drive is: was attained by turning of the valve member 41 and this control may be connected up in any desired manner to be actuated automatically by conditions in the driven mechanism or related apparatus.
- the direction of rotation of the motor may be reversed by reversing the rotation of the control valve 41 to bring the pressure chamber 53' into connection with passage 15 and the discharge 56 opening from passage 13.
- the control of the speed acts in the same manner'on clockwise rotation (Fig. 2) so that the motor may be driven in either direction at all speeds up to the maximum and the control is continuous throughout.
- the pump 35 may be of any desired'type and driven through a shaft protruding from the housing in either direction.
- has a shaftfi2 with through the valve and motor parts.
- the piston plungers 21 have no complicating connections or valves and are normally held in contact with the surface of the ring 24 and are retained in their cylinders 20 by the overhanging portion of the cylindrical surface l9 (Figs. 1, 2 and 3).
- the pressure supply may-have a relief bypass 10 from the pressurepassage 40 to the sump chamber 38 containing a resilient valve device 11 opening under predetermined excess of pressure to protect the apparatus and permit a fluid flow and circulation from the pump discharge around to the pump intake without passing
- the ends of the control member 41 may be packed to retain the pump pressure and have a pressure relief outlet 12, 13 bleeding back any leakage into the sump chamber 38 so that the end of the shaft is protected against the trapping and building up of excessive fluid pressures.
- a similar relief passage 15 is added to the extension H between bearings 9 in order to prevent the building up of excessive fluid pressure.
- the piston plungers 18 may be provided with extended surface contact with the offset bearing ring 11 by forming the cylindrical seat 19 and rotatably fitting in it the shoe having a segment of its periphery 8
- a rotary hydraulic machine comprising a driven shaft, a rotor-mounted on said shaft in annular formation with radially directed cylinders and pistons freely and independently mounted therein and projecting within said annular formation, a stator housing said rotor and having open-ended intake and exhaust chambers peripherally surrounding said rotor in communication with the outer ends of said cylinders and said pistons, a fixed member eccentrically positioned within said annular formation of said rotor and within the inner ends of said cylinders and having an outer piston-engaging ring running on anti-friction bearings, said pistons having curved end surfaces integral with and in fixed relation to said pistons in pivotal contact with said ring and closelyapproaching each other in near contact adjacent the said ring and pressing against said ring on application of'hydraulic pressure to saidpiston rotating said rotor and turning said piston about said contacting portion of said curved surfaces as the ring moves with said rotor and piston.
- a rotary hydraulic machine as set forth in claim 1 in which said curved surfaces are convex and roll on the outer surface of said ring as said rotor rotates.
- WALTE References on following page
Landscapes
- Engineering & Computer Science (AREA)
- General Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Hydraulic Motors (AREA)
Description
Oct. 7, 1952 J. 'G. WALTER 2,612,873
FLUID POWER CONVERSION APPARATUS Filed April 5, 1946 2 SHEETS SHEET l BY I o NEY Oct. 7, 1952 J WALTER 2,612,873
FLUID POWER CONVERSION APPARATUS Filed April 3, 1946 2 SI'IEETS-SHEET 2 Patented Oct. 7, 1952 N TED. STATES PATENT @FUIEI'ID POWER EONVERSION APPARATUS Jules Wa ter, i il ofii LY ass en t9 Samcoe Holding (Corporation, New York, Y a corpora tiono'fiNew lurk V I v Application April 3, 1946,,Serial No. 659,176
1 v i I This invention relatesto variable speed drives and particularly vto a drive employin a filliil pump and motor. 1
The object of the invention istonrovide a d iv of this type which .will be simple, inexpens e a eificient and which will (provide 1 01:84 progressive, easily controlled variation in the sp ed 9 th motor. v
Further obj ects of tthejinvention, particularly in the control and reversal of the operation and'the special operative features ofih m tor pist n engaging a central eccentric, will appear from the following ription taken i c nn c io with the accompanying-drawings in which Fig. 1 is aplan view with partsin s ctionon line i-'-I ofFig. 2,; i
Fig.2 is a front eleyational-view-with theiront plate omitted; r
Fig. 3 is a vertical sectional view taken on-line 3-3 of Fig. 2;
Fig. 4 is a perspective view in-detail of control valve on enlarged scale; and
Fig. 5 is a sectional view illustrating a-modified form of engagement between the plun gers and eccentric ring.
In the embodiment shown inthe;drawin s, the rotor comprises a shaft 6 (Fig. 3) vcarryingthe rotor head 1 and running in bearings-9 in the extension ll of the stator casing HL'carriedby the base 8, a cover l2 being fastened to the stator casing mas-shown.
.When the motor rotor I revolves counter-clockwise (Fig. 2) :the fluid passes under pressure in through .the passage [3 to the intake distributing chamber 14 and is discharged through the pastied by thermal .21 are s t e co e 1' ilir h sage l5 from the collecting chamber 16, these passages [3, H3, 15 and. I6 being formed inthe stator casing l0 as shown.
Between the intake and collecting chambers. l4 and H; are the separating -.contact-areas t1, t8 having'grooved arcuate surfaces fiush with the inner'cylindrical surface IQ of the casing 10. The edge of this cylindrical surface l'9 overhangs the outer endspof the radial cy1inders20-toretain the piston plungers '2 I in a the cylinders :and against escape therefrom'into the chambers 14 and It whenever the centrifugal forces are sufficient-to overcomethe pressures against thepiston head.
The rotor Tslidingly fitsthe cylindrical surface lfland the radially directed inner surfaces 29, 3l1 (Fig. 3) of the stator ill-and cover [2. Radial cylinders 20 in the'rotor are fitted lwith piston plungers .2 I, each plunger comprisinga, cylindrical piston portion 22 and a rounded inner or.
head-end 23 engaging the periphery of a ring 24 running on bearing balls 25 on raceways 26 car- [2 Claims. (01. 121-59) screw halt 2.8. the-axis o a s mb Z1 and2 be n offset a shown w h ,m V x o r to ..-lto prov de the desi e trici v i J V v the on raticn o 1 2 2. e ee at isc s t r clock s motet, fluid "Pres erll ad tted th ug the :on ssase 1 and d t but d BY the chamb r 14 to t e head .22 of he 91mm 9i the cy n 9 "ccmmun cat es w t the 9 her Id. The resultant pressure of the er r und d sa of the l n e v2. a ems t'fi ofiset bearin 11115 2 Q. as transmittedthrqugh the a in ha a ange t a .o fi c .ent in he re t o th a row I'm-2 w i h 14 mined h ou ou th a o ardmoremrt of the ..p n. e :The ha st q isi ch'a ee om th m r l ase t ilid imm h tyneders 2 n t ollec ng c amber egend the! pass g 1 tee ing th fm s ure we (the P e? a the re m ed p twalf lthe ff set bearing ring 24 during, their upward ttravellin mmunic Wi th fw11 tihg LAs thep nsers ;m einwar ei d: pe i crli ersy h und s q. 1 9f ;t P. dihsl smi in .ip'h yrei h fis b e e in E due-t0 =i n e -sieve Shift their a g lar posi i n vw re, pn t9 x io th -.-ecentric- Theglr uni of t e ea s'fl readil permi this rq i. ment with negligible friction, the ofiset' b e ring 24rotating. at substantially ,the sanieasnthe rotor t1. Thewgrip of this rollin I V of.these.hea,ds,2.,3isf ufiicientto, .ganv st ti i g betw e -th *rin oe i d the plun'gers. f :Th res t nto ar t rqu o th rotor" communicated tothershaft; thre s me msthe fl i ip'r-es ilre pcv r rece es at pas age r taivm vejment tth osha ttfi- Afluid pump 35 to supply pressure for the moto -isghquseo i h pum chamber 36 9f: t as T nem t -1211;1 9:3 5 ispre dfl rhr verti al intake- ,sun,1 :chembr1-3 it a asaahollow reservoir inbaseia. The ilul pressure output o pumpfi i delirere othr bi h sagefAUtothe rear end 4] oi centr al ma 0 2 n ne h fr wave latwpendi f the s an q mun e neia t he ir nt'ii'e q with I the passages I. I3, and -l;.5an d .yvllth', the, discharge i e 'se ev n n dqw lint it iaisumr chamber 38. c 1
vA- dric l ,ralr mem er 14: i r ate-Pl fitt d i manioiold ch mher str nd; is
to-provideh an annular spa ejjjlea q' v QPenins-4 i t :t e QQMQ AIWi QQ JQW-JDQIF tending forward to the passage 51 leading radially outward to the end chamber 53 provided by the arcuate peripheral recessing of the end of member 41 leaving this crescent-shaped pressure supply chamber 53. The opposite side of the end of member 41 is cut away at 55 to form the crescent discharge passage 56.
In the central position of valve member 41 (Fig. 2) both the pressure supply 53 and discharge 56 are out of communication with the passages l3 and to the motor, and then assuming that the pump 35 is running, its pressure fluid passes through passage 40 to'chamber 48, opening 49, bore 50 and by-pass 51 in the" valve and outlet passage 58 in the base structure to sump chamber 38 and back to the pump. No power is applied to drive the motor.
When the motor is to be driven counterclockwise (Fig. 2) the valve member 41 is turned counter-clockwise by means on the outer end of the control shaft 59 extending forward from the member 41. The'flrst portion of this valve movement connects pressure chamber 53 to passage l3 and chamber l4 to supply fluid pressure to' the piston 2| on the left side of the rotor (Fig. 2 and at the same time discharge'chamber 56 of the valve is connected to the passage l5 and'chamber 16 to permit outflow of fluid from the cylinders 20 on the right side of the [The initially applied pressure is low because of the bleeding of thefluid through by- passes 51, 58 into the sump, and as the valve 41 continues to turn, this by-pass relief is progressivelylchoked off until finally the valve opening 51 is entirely out of register with the matching drain' 58, whereupon full pressure is applied to the driving side of the motor and the exhaust side is connected freely to the discharge through 1 valve chamber 56 and passage 45 into the sump.
The driving pressure will therefore depend on the position of the valve member 41 and for a given resistance to the motor drive the motor speed will vary with the .applied driving pressure. Control of the speed of the motor'drive is: was attained by turning of the valve member 41 and this control may be connected up in any desired manner to be actuated automatically by conditions in the driven mechanism or related apparatus.
The direction of rotation of the motor may be reversed by reversing the rotation of the control valve 41 to bring the pressure chamber 53' into connection with passage 15 and the discharge 56 opening from passage 13. The control of the speed acts in the same manner'on clockwise rotation (Fig. 2) so that the motor may be driven in either direction at all speeds up to the maximum and the control is continuous throughout. I p l I The pump 35 may be of any desired'type and driven through a shaft protruding from the housing in either direction. In the form shown the upper pump'gear 6| has a shaftfi2 with through the valve and motor parts.
of the motor rotor. The piston plungers 21 have no complicating connections or valves and are normally held in contact with the surface of the ring 24 and are retained in their cylinders 20 by the overhanging portion of the cylindrical surface l9 (Figs. 1, 2 and 3).
' The pressure supply may-have a relief bypass 10 from the pressurepassage 40 to the sump chamber 38 containing a resilient valve device 11 opening under predetermined excess of pressure to protect the apparatus and permit a fluid flow and circulation from the pump discharge around to the pump intake without passing The ends of the control member 41 may be packed to retain the pump pressure and have a pressure relief outlet 12, 13 bleeding back any leakage into the sump chamber 38 so that the end of the shaft is protected against the trapping and building up of excessive fluid pressures. A similar relief passage 15 is added to the extension H between bearings 9 in order to prevent the building up of excessive fluid pressure.
The showing described is a typical embodiment and various modifications may be made within the scope of the invention. As indicated in Fig. 5 the piston plungers 18 may be provided with extended surface contact with the offset bearing ring 11 by forming the cylindrical seat 19 and rotatably fitting in it the shoe having a segment of its periphery 8| conforming to the arc of the offset bearing ring.
The invention has been shown and described in connection with a specific embodiment, but it is not intended to be confined thereto, the principle of the invention broadly covering the subject matter as set forth in the appended claims.
I claim:
1. A rotary hydraulic machine comprising a driven shaft, a rotor-mounted on said shaft in annular formation with radially directed cylinders and pistons freely and independently mounted therein and projecting within said annular formation, a stator housing said rotor and having open-ended intake and exhaust chambers peripherally surrounding said rotor in communication with the outer ends of said cylinders and said pistons, a fixed member eccentrically positioned within said annular formation of said rotor and within the inner ends of said cylinders and having an outer piston-engaging ring running on anti-friction bearings, said pistons having curved end surfaces integral with and in fixed relation to said pistons in pivotal contact with said ring and closelyapproaching each other in near contact adjacent the said ring and pressing against said ring on application of'hydraulic pressure to saidpiston rotating said rotor and turning said piston about said contacting portion of said curved surfaces as the ring moves with said rotor and piston.
2. A rotary hydraulic machine as set forth in claim 1 in which said curved surfaces are convex and roll on the outer surface of said ring as said rotor rotates.
3. A rotary hydraulic machine as set forth in claim 1 in which there is a slidable convex surface in frictional gripping relation with said ring and mating with a concave surface, said concave surface pivoting said piston around said contact surface to turn said piston in relation to said ring- JULES G. WALTE (References on following page) REFERENCES CITED The following references are of record in the file of this patent:
UNITED STATES PATENTS Number Name Date Dyer et a1. Dec. 19, 1899 Deakin Sept. 9, 1902 Vincent Apr. 13, 1915 Lentz Oct. 5, 1915 10 Painter et a1. Oct. 2, 1917 Wilsey June 28, 1927 Beattie Dec. 29, 1931 Maw Apr. 18, 1933 Number Number Name Date Ernst Apr. 16, 1935 Johnson Dec. 19, 1939 Ferris Jan. 9, 1940 Tweedale Apr. 1, 1941 Kucher Aug. 17, 1948 May Aug. 24, 1948 Peterson Sept. 19, 1950 FOREIGN PATENTS Country Date 1 Sweden Dec. 17, 1900 Great Britain Aug. 16, 1913
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US659176A US2612873A (en) | 1946-04-03 | 1946-04-03 | Fluid power conversion apparatus |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US659176A US2612873A (en) | 1946-04-03 | 1946-04-03 | Fluid power conversion apparatus |
Publications (1)
Publication Number | Publication Date |
---|---|
US2612873A true US2612873A (en) | 1952-10-07 |
Family
ID=24644354
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US659176A Expired - Lifetime US2612873A (en) | 1946-04-03 | 1946-04-03 | Fluid power conversion apparatus |
Country Status (1)
Country | Link |
---|---|
US (1) | US2612873A (en) |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4467604A (en) * | 1979-12-24 | 1984-08-28 | Linde Aktiengesellschaft | Hydrostatic drive system for an excavator |
Citations (16)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US639541A (en) * | 1897-05-04 | 1899-12-19 | Frank L Dyer | Automobile vehicle. |
US708697A (en) * | 1901-12-05 | 1902-09-09 | Charles Herbert Deakin | Engine. |
GB191318670A (en) * | 1913-08-16 | 1914-08-13 | Rotoplunge Pump Company Ltd | Improvements in Rotary Pumps and Motors. |
US1135414A (en) * | 1914-03-07 | 1915-04-13 | William John Vincent | Rotary pump and motor. |
US1156015A (en) * | 1914-10-21 | 1915-10-05 | Hugo Lentz | Fluid change and reversing gear. |
US1242033A (en) * | 1916-06-30 | 1917-10-02 | Albert E Painter | Fluid-pressure transmission. |
US1633720A (en) * | 1925-08-24 | 1927-06-28 | J B Tuthill | Pump |
US1838733A (en) * | 1929-02-16 | 1931-12-29 | L S Murray | Power transmission mechanism |
US1904496A (en) * | 1929-03-20 | 1933-04-18 | Maw Robert | Hydraulic transmission system |
US1998004A (en) * | 1930-05-23 | 1935-04-16 | Cincinnati Milling Machine Co | Differential hydraulic speed gear |
US2184219A (en) * | 1938-02-11 | 1939-12-19 | Jesse C Johnson | Hydraulic transmission |
US2186409A (en) * | 1937-06-07 | 1940-01-09 | Oilgear Co | Hydraulic transmission |
US2237018A (en) * | 1937-02-11 | 1941-04-01 | Waterbury Tool Co | Power transmission |
US2447348A (en) * | 1943-05-21 | 1948-08-17 | Bendix Aviat Corp | Hydraulic drive |
US2447707A (en) * | 1945-07-31 | 1948-08-24 | Westinghouse Air Brake Co | Control apparatus for a plurality of motors |
US2522890A (en) * | 1945-08-22 | 1950-09-19 | Adolphe C Peterson | Fuel metering, distribution, and control means |
-
1946
- 1946-04-03 US US659176A patent/US2612873A/en not_active Expired - Lifetime
Patent Citations (16)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US639541A (en) * | 1897-05-04 | 1899-12-19 | Frank L Dyer | Automobile vehicle. |
US708697A (en) * | 1901-12-05 | 1902-09-09 | Charles Herbert Deakin | Engine. |
GB191318670A (en) * | 1913-08-16 | 1914-08-13 | Rotoplunge Pump Company Ltd | Improvements in Rotary Pumps and Motors. |
US1135414A (en) * | 1914-03-07 | 1915-04-13 | William John Vincent | Rotary pump and motor. |
US1156015A (en) * | 1914-10-21 | 1915-10-05 | Hugo Lentz | Fluid change and reversing gear. |
US1242033A (en) * | 1916-06-30 | 1917-10-02 | Albert E Painter | Fluid-pressure transmission. |
US1633720A (en) * | 1925-08-24 | 1927-06-28 | J B Tuthill | Pump |
US1838733A (en) * | 1929-02-16 | 1931-12-29 | L S Murray | Power transmission mechanism |
US1904496A (en) * | 1929-03-20 | 1933-04-18 | Maw Robert | Hydraulic transmission system |
US1998004A (en) * | 1930-05-23 | 1935-04-16 | Cincinnati Milling Machine Co | Differential hydraulic speed gear |
US2237018A (en) * | 1937-02-11 | 1941-04-01 | Waterbury Tool Co | Power transmission |
US2186409A (en) * | 1937-06-07 | 1940-01-09 | Oilgear Co | Hydraulic transmission |
US2184219A (en) * | 1938-02-11 | 1939-12-19 | Jesse C Johnson | Hydraulic transmission |
US2447348A (en) * | 1943-05-21 | 1948-08-17 | Bendix Aviat Corp | Hydraulic drive |
US2447707A (en) * | 1945-07-31 | 1948-08-24 | Westinghouse Air Brake Co | Control apparatus for a plurality of motors |
US2522890A (en) * | 1945-08-22 | 1950-09-19 | Adolphe C Peterson | Fuel metering, distribution, and control means |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4467604A (en) * | 1979-12-24 | 1984-08-28 | Linde Aktiengesellschaft | Hydrostatic drive system for an excavator |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
US2778317A (en) | Rotary fluid pressure pumps and motors of the eccentric vane type | |
US3516769A (en) | Rotary vane hydraulic motor | |
JP4342647B2 (en) | Back pressure groove structure of variable displacement vane pump | |
US4091717A (en) | Ring dampener for rotary fluid pressure device | |
US4518069A (en) | Adjustable speed drive utilizing radially movable hollow pistons which act on a cam surface | |
US2612115A (en) | Vane pump and vane therefor | |
US2132813A (en) | Rotary engine | |
US1819689A (en) | Hydraulic pump | |
US4008018A (en) | Rotary fluid displacement device having improved porting | |
US3495539A (en) | Rotary pump | |
US2612873A (en) | Fluid power conversion apparatus | |
US4347047A (en) | Hydraulic pump for power steering | |
US3303749A (en) | Hydraulic motors | |
US5032069A (en) | Rotary position displacement pump or motor | |
US3813189A (en) | Low fluid fluid motor | |
US2728297A (en) | Variable capacity pump | |
NO123820B (en) | ||
JPH04237675A (en) | Power steering system | |
US2557427A (en) | Rotary pump or hydraulic turbine | |
JPS59711B2 (en) | multiple pump | |
GB511298A (en) | Improvements in or relating to liquid pressure control systems | |
GB596902A (en) | Improvements in or relating to rotary pumps and rotary fluid-pressure motors | |
US3563679A (en) | Pressure-compensated gear-rotor hydraulic motor or pump | |
US2679306A (en) | Hydraulic coupling | |
US4331421A (en) | Reversible unidirectional flow pump with axial frictionally engaged recessed valve plate |