US2538842A

US2538842A - Pump

Info

Publication number: US2538842A
Application number: US711383A
Authority: US
Inventors: Artie F Mcfarland
Original assignee: MCFARLAND Manufacturing CORP
Current assignee: MCFARLAND Manufacturing CORP
Priority date: 1946-11-21
Filing date: 1946-11-21
Publication date: 1951-01-23
Anticipated expiration: 1968-01-23

Description

A. F. MCFARLAND PUMP Jan. 23, 1951 5 Sheets-Sheet l Filed Nov. 21, 1946 @imma/25 3 sheets-Sheet 2 PUMP A. F. MCFARLAND Jan. 23, 1951 Filed Nov. 21, 194e losa los

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Fig 3 Jan. 23, 1951 A. F. MCFARLAND PUMP 3 Sheets-Sheet 5 Filed Nov. 21;( 1946 mw m Nm ww w mw l .um/ 5 5w Patented Jan. 23, 1951 PUMP Artie F. McFarland, Houston, Tex., assignor to McFarland Manufacturing Corporation, Houston, Tex., a corporation of Texas Application November 21, 1946, Serial No. 711,383

(Cl. 10S- 49) 21 Claims.

This invention relates to improvements in uid actuated pumps and refers more particularly to the arrangement of ports and passages for both the power iiuid and uid to be pumped and to means for increasing the discharge pressure of the pumped uid.

An object of this invention is to provide a pump in which the surging of fluid during the operation of the pump does not impart forces to ther4 pump body tending to produce lateral movement of the body on its mounting.

Another object is to provide a pump which may be used in numerous manners to pump iiuid at varying pressures.

A further object is to provide a pump having low pressure and high pressure booster sections, which is particularly adaptable for use in testing boilers, tanks, well heads, Christmas trees and the like, wherein the container to be tested may be filled by the high volume low pressure section and tested by the high pressure booster section.

Yet another object is to provide a pump having low pressure and high pressure booster sections communicating -With common inlet and discharge lines in which the sections may be selectively utilized by manipulation of a single Valve.

Yet a further object is to provide a pump having low pressure and high pressure booster sec- `tions wherein an automatic valve is operable to selectively actuate the sections individually in response to the pressure in the discharge line.

Other and further objects will appear from the following description: v

In the acco-mpanying drawings which form a part of the instant specification and are to be .r

read in conjunction therewith and wherein like numerals are used to indicate like parts in the various views:

Fig. 1 is a. vertical sectional view of a pump embodying this invention,

Fig. 2 is a fragmentary sectional view of the pump in Fig. 1 showing an auxiliary power attachment,

Fig. 3 is a view taken along the line 3-3 in Fig. 1 in the direction of the arrows,

Fig. 4 is a fragmentary view taken along the line 4-4 in Fig. 3 in the direction of the arrows,

Fig. 5 is a top plan view of the pump shown in Fig. 1, having a booster section mounted there- Fig. 6 is an enlarged horizontal section throug the booster section and a part of the low pressure section of the pump illustrated in Fig. 5, and

Fig. 7 is anenlarged sectional detail of the regulator shown in Fig.l 5. l

Referring to the drawings, the pump illustrated in Fig. 1 will be first described. The pump comprises a body I0 having a cylinder bore II therethrough. The body has an internal boss I2 formed in the cylinder bore intermediate its ends. The boss I2 carries an annular packing assembly I3. A double element piston with piston heads i4 and I5 connected by cylindrical member I6 extends through packing I3.

Packing I3 and the double element piston divide the cylinder bore into power cylinders I1 and I8 at the ends of the piston heads and intermediate pump chambers I9 and 20 for uid to be pumped. An end plate 2I is removably secured to the right end of the cylinder bore and carries an annular bumper 22 of resilient material such as synthetic rubber or the like to limit movement of the piston in one direction. The other end of the cylinder bore is closedby a removable cap 23, which also carries a bumper 22. The cap will be hereafter more fully described in connection with means for controlling the introduction of power fluid to the power chambers.

Ports and passages are provided in body I for introduction of power iiuid to the power cylinders and fluid to be pumped to the chambers I9 and 25. A port 24 communicates with cylinder I'I. This cylinder also communicates with passages 25, which extend longitudinally of body Il) to the right end of the cylinder and are closed by plate 2|. Preferably, two of these passages 25 are provided in the body. These passages are substantially of equal cross sectional area throughout their length. Two passages 21 are provided in body II) for supplying and exhausting power fluid to cylinder I8. Ports 28 and 29 in body I0 communicate with chambers I9 and 20, respectively.

Ports 24, 23 and 29 are arranged at the top of body I0 and are centered on a vertical plane including the cylinder bore axis. Each of the passages 25 and each of the passages 2'I are spaced equally from a vertical plane including the cylinder bore axis. This arrangement of ports and passages is such that the forces due to surging of fluid therethrough are counterbalanced and do not tend to move the pump body I0 laterally or rotate the pump body lll on its base supports 26. Preferably, the body I5 is a casting having ports 2B, 28 and 29 and passages 25 and 2'I formed therein at the time of the casting. 1 f

Referring now to the valves for the introduction of fluid to be pumped t0 chambers I5 4and 20, it is seen that reservoirs 30 and 3l are provided at the top of bodyvlll communicating with ports 28 and 29, respectively. These reservoirs pressure and are seated by excess discharge pre'ssure relative to the reservoir pressure.

With reference to the control of power uid to the power cylinders, a valve cage V36 is provided in cap H19 above divider plate 35. The cap has a power iiuid inlet connection iSa. The divider plate has three ports a, 35h and 35C. Port 35a communicates between cage 36 and passages 2.

Port 35C communicates between cage 3G and port 24. The middle port 35D communicates with eX- haust 3l. A slide valve 3S is mounted for recipyi'ocal sliding movement within cage 36 and has vra'rrecess which in one position of the valve makes connection between ports 35C and 35h whereby expended power fluid from cylinder l'i may be exhausted through port 3l. Slide valve 38 in its other extreme position places port 35a in communication with port 35h whereby expended power fluid from cylinder i8 may be discharged. Valve member 38 is shifted in response to the position of the double element piston within the cylinder bore. This is accomplished by means 'of a mechanical tripped valve which controls a fluid actuating mechanism for valve 38. Valve 38 is attached by stem 3S to piston 4Q. The piston is reciprocally mounted in cylinder 4 The cylinder aperture through which stem 39 extends has` :a stuffing box to prevent leakage of fluid from the cylinder. Power fluid may be introduced to cylinder 4l on opposite sides of piston 40 to shift the position of the piston and thereby shift slide valve 38.

Power fluid flow to cylinder 4| is controlled Yby the mechanically tripped valve housed within cap 23. Cap 23 has connections@ and 43 with cylinder 4I communicating on opposite sides of piston 40. The cap also has an inlet connection '4"4 for power fluid and a discharge connection 45.

vA valve member 45 is mounted within the cap 23 and controls the flow of power fluid and expended power fluid through connections 42 and 43. rThis Yvalve member 45 is cylindrical in shape with a longitudinally extending groove 46a in its periphery. This groove is engaged by aligning screw 4l and communicates with the inlet connection 44 whereby power fluid may flow past member 46 `to both ends of the valve member. Thus with the valve in the position shown in Fig. l the fluid passes from connection 44 through groove 46a and connection 42 to cylinder 4l, driving the piston 4i! to the position shown. Valve 4G has a recess 45h in its periphery. This recess makes communication between connection 43 and discharge v45 so that expended power uid in cylinder 4l is exhausted when piston moves to thev position shown in Fig. 1.

The arrangement of valve 4E is such that when shifted in the cylinder of cap 23 to the left end of the cylinder the recess 46h makes communication between connection 42 and discharge 45, and the connection 43 is exposed. Thus with the valve 46 in its shifted position power fluid'-is introduced through line 43 tothe left end of cylinder 4I to move piston 4i] to the right. During movement of' the piston expended power fluid is discharged through line 42, recess 4Gb and discharge line 45.

A connection is provided between valve and the double element piston whereby the valve is mechanically tripped by the travel of the power piston as it reaches predetermind positions (usually the ends of the cylinder bore) within the cylinder bore. This connection includes the rod 4S attached to valve 46 and extending into the well of member 49 of cylinder head I4. The rod carries a stopin at its end -within the well and a stop 48b intermediate its ends. Rod 48 extends f through apertured plug 50 threaded in the well of member 43. The aperture of plug 5Fl is smaller than the diameter of stops 48a and 43h whereby the plug engages these stops as the piston travels within the bore.

With the parts arranged as illustrated in Fig. 1, power fluid is introduced through passages 21 to cylinder t8 to drive the double element piston toward the left. As the piston continues to move tothe left, plug 50 will engage stop 48h, and cong tinued movement of the piston will move valve 45 to the left until recess 4519 covers the

connections

42 and 45. When this is accomplished power uid passes from cap 23 through connection 43 to cylinder 4i to drive piston 40 to the right. With piston 4S in its extreme right position, valve 3S has been shifted so that its recess covers ports 35a and 35D in the divider plate, and power fluid is then introduced to cylinder il, whereby thedouble element piston is driven to the right.

" As the movement of the piston to the right continues1 plug 5) engages stop 48a, to shift valve 46 to position shown in Fig. 1. rThis again reverses flow of power fluid to cylinder 4l to shift valve 38, whereby power -uid is again introduced to power cylinder i8, changing the direction of travel of the double element piston.

It will be understood that the area Yof each of the piston heads I4 and l5, which is exposedfto fluid to b e pumped, is small relative to theouter faces of the piston heads'exposed to the power fluid. For this reason the pressure of the'fluid to "be pumped is great relative to the kpressure of the power fluid. Obviously, the diameter of the cylinder connection l between the piston heads i4 and i5 may be varied to change the pressure ratio of the pumped fluid to' the power fluid. However, as the diameter of connection'Itl is increased to increase the 1pressure, the volume capacity of the pump is decreased vpropo'rtionately. Thereforeit is often desirable'to increase the pressure of the pumped uid without at vthe same time decreasing the volume capacity of the Dump.

The auxiliary power attachment sho-'wn in Fig. 2 is provided to increase the discharge'pr'essure of the pump. The attachment comprises` a cylinder housing 5| with an end-plate'52-- -A piston 53is mounted within the housing and is attached by rod 54 to piston head l5'. Thefrod'vllextends through a stuffingv box to prevent intermingling of iiuids. The housing 5| has passages 55corre sponding in number and communicating with pa'ssages 21 to supply power fluid tothe rightside of piston 53 at the same timepowerffluid is supplied to cylinder I8. Ports 56 communicate through passages formed in housing 5l with passages 25 of the body I0. Thus, power fluid is introduced to the left side of piston 573 through ports 24, passages 25 and ports 56. The expendedpoweriiuid is exhausted from either side of the piston through supplied. By this expedient, the pressure of the pumping fluid may be substantially doubled Without decreasing the volume capacity of the pump.

While the diameter of the bore of the cylinder housing 5| is substantially the same as the cylinder bore of body l0, it is contemplated that the diameter of the bore of the auxiliary housing may be varied to either increase or decrease the degree of pressure step-up.

Referring to the modification shown in Figs. 5 and 6, it will be seen that there is provided a high pressure booster section which may be utilized in conjunction with the relatively low pressure pump section shown in Fig. 1. The booster section is attached to body ||l by removing end plate 2| and securing in its place end plate 69 of the booster section.

The booster cylinder is made up of the cylindrical member 6| and the cylinder heads '62 and 63. Cylinder heads 62 and 63 are annular in shape and have large diameter bores 62a and 63a which receive the ends of member 6 I. O-rings or other sealing means are disposed between the ends of member 6| and the abutting shoulders of the cylinder heads to form a seal therebetween. The cylinder heads and cylinder member are held together as a unit by through bolts 64. These bolts also secure the booster unit to plate 60. The bumper Il@ surrounds the male portion of cylinder 62 and limits the stroke of the double element piston.

The cylinder heads have bores of reduced diameter which are of substantially the same diameter as the bore of member 6|. The bores of the cylinder heads and member 6| are coaxial with the cylinder bore of body Il). A booster rod 65 extends through the cylinder heads, and one end is secured to piston element l5 of the double element piston. The other end of rod 65 serves as a guide and is housed within dome l I. Each of the cylinder heads carries a packing gland surrounding rod 65. Rod 65 carries suitable packing 66, which serves as a piston'on plunger within the cylinder bore of member 6I.

Each of cylinder heads 62 and 63 has radial bores communicating with the reduced diameter bores. These radial bores serve as inlet and outlet ports for the booster cylinder. Check valves are provided for these ports. In the case of the inlet ports, the check valve balls 61 seat against shoulder 58 of fittings 69. The balls are urged against their seat by springs 10. In the outlet or discharge ports, the ball valves and springs are reversed whereby the springs urge the valves into seating position against the cylinder head port. The inlet ports communicate with the supply line 7| for uid to be pumped. Line 12 provides a connection with one of the inlet ports and line 1|. Line 13 forms a part of the connection for the outlet ports to the discharge line '14. A pressure gauge may be incorporated in the discharge from the booster.

A iluid to be pumped may be supplied to the low pressure section and the booster section by a common supply line 16 through branches 'Il and l1. A common discharge line 14 may also communicate with the exhaust of both sections. It is preferred to place a check valve 18 in the discharge line between the two sections.

In order that the low pressure section and high pressure booster section canbe selectively and interchangeably used, a pipe 'I9 is provided between the inlet and exhaust ttings 32 and 33. This pipe may be equipped with a manually .oper- 6 ated valve S, and preferably has disposed'therein a' combination valve and regulator 8|. The regulator 8| has a connection with the discharge line 'lli on the downstream side of check valve 7S through conduit 82.

The valve and regulator is detailed in Fig. 7 and comprises a cylindrical casing made up or" two

parts

83 and 83 having a threaded engagement. Part 84 has a bore 84a which slidingly receives the stern of valve member 85. Packing gland 85 retains packing material 8l in an enlarged diameter bore surrounding the valve stem. The stem of valve 85 extends into a chamber formed by an enlarged diameter bore Elib of part 86 and abuts shoe 88. Shoe 88 has a flange which engages one end of coil spring S9, the other end of the spring engaging a threaded plug 96. A second spring 9| is carried by the head oi" bolt 92 in the line of travel of shoe 88. Bolt 92 has a threaded engagement with plug 93 and may be advanced toward or retracted from shoe .33 te adjust the pressure exerted by the spring against valve 85.

Part 83 has an enlarged cylinder bore 93 in which fits seat ring 94. Packing material is disposed between ring Sil and shoulder 83a of part 83. A sleeve insert 95 holds seat ring Sil securely in position when parts S3 and Sl are assembled. Ports 83h and 83e are provided for connection in conduit 19.

Valve 85 is urged by spring 89 against seat94 to close the passage through the cylindrical casing. In order that the valve may be opened in response to pressure within the discharge line, a plunger stem 96 is secured to valve 85 and extends through the seat ring into the bore of tting 91. This tting in turn is connected to the discharge line 'M through the conduit 82. Thus the end of plunger 96 is exposed to pressure within the bore 0f fitting 97 equal to the discharge pressure. When this pressure is great enough to collapse spring 89, valve 83 is opened, and the intake and exhaust iittings 32 and 33, respectively, are placed in communications with each other. Spring 9| does not engage shoe 38 until Valve 83 has been unseated. This spring is` stiller than spring 89 and when it is engaged retards further movement of valve 85 until the discharge pressure is suicient to overcome the combined springs 8S and 9|. A second valve member 98 is carried by plunger rod 96 and seats against ring 94 when the discharge line pressure exceeds a certain value. By rotation of bolt 62, the upper pressure at which the valve is closed may be adjusted.

In operation of the low pressure and high pressure booster sections, the pump sections are assembled as illustrated in Fig. 5. The pump then may be used for any normal pumping purpose, but is especially adapted for use in testing appa.- ratus such as boilers, well heads, Christmas trees and the like. When a testing job is to be performed, it is usually preferable to use a hydraulic fluid as the test uid. The low pressure section is utilized as the pumping means until the container to be tested has been lled. This is desirable because of the greater capacity of the low pressure pump as compared with the booster. Spring 89 of regulator 8| is set so that valve 85 will open when the pressure within discharge line 14 approaches the pressure output of the low pressure section. With valve 85 open, inlet and outlet fittings 32 and 33, respectively, are placed in communication, and the low pressure section ceases to act as a pump because of the equalization of the pressures. With valve 85 seated, the

volumecapacity of the low pressure section is so great as compared with the volume capacity of the booster section that the booster section is substantially ineffectual. However, with valve B5 unseated, the low pressure section becomes ineffectual, and all the fluid pumped must pass through the booster section. Back pressure valve 18 is seated by the pressure developed by the booster section, and the pump continues in operation until the discharge pressure is great enough to move plunger 96 against the springs B9 and 9| to the point that valve member S8 seats against seat ring 94. When this occurs, conduit 19 is again closed, and the pump immediately locks and remains ineifective until the pressure in the discharge line has been released.

By this arrangement high volume pumping may be accomplished at pressures in the neighborhood of 200 pounds per square inch by utilizing the ordinary water pressure in most city mains, which is usually about 60 pounds per square inch. The area ratio between the double element piston and piston or plunger 56 of the booster section is such that pressures in the neighborhood of 12,000 pounds can be developed by the pump utilizing ordinary city water as the power source.

In the event additional pressure is desired from the booster section, it may be readily obtained by utilizing the pump chambers i9 and 2E as auxl iliary power cylinders. For this purpose corn duits |00 and ||J| are provided in communication with chambers |9- and 2B, respectively. Conduit |00 communicates with passages 2l through T connection |62 and conduits |03 and |54. valve |615 controls vfiow through these conduits. Conduit l communicates with passages 25 through conduits |06 and i6?, and iow is controlled through these conduits by valve |53. Ildy opening valves |05 and iBS, power fluid is introduced to and exhausted from chambers i9 and 20. The arrangement is such that chamber I9 is energized simultaneously with power cylinder I8` and chamber 2D' is energized simultaneously with power cylinder Il. Thus the active area of the doubllerelement piston which is exposed to power fluid at any one time is increased by the area of pistons I4 and E5 that are exposed to chambers I9 and 2li, respectively.

When the valves |65A and it@ opened, the pressure within reservoirs 3G and 3i is greater than the pressure in intake line l?, and the poppet intake valves are held seated by the pressure within the reservoirs. Pressure in dischargeline 'i4 down stream from check valve 18 is greater than the pressure with-in the exhaust fitting 33, and the check valve is seated by this pressure` It is then apparent that with valves 94 and m8 open the poppet intake and exhaust valves are held closed automatically and the chambers E9 and 253 become a part of the power system whereby the entire low pressure section is utilizedv asia motor for actuating the booster piston t6.

From the foregoing it will be seen that this invention is one -well adapted to attain all oi' the ends and objects' hereinabove set forth, together with other advantages which are obvious and which are inherent to the structure.

It will be understood that certain features and subcombi'nations are of utility and may be employed without reference to' other features and subcombinations. This is contemplated by and is within the scopeof the claims.

As many possible embodiments may be made of the invention without departing from the scope thereof, it is to be vunderstood that all matter herein set forth or shown in the accompanying drawings is to be interpreted as illustrative and not in a limiting sense.

Having described the invention, what is claimed l. In a fluid actuated pump having a body having a support and with a cylinder bore, means including a piston mounted within the bore dividing it into two power cylinders at the ends of the piston and intermediate chambers for fluid to be pumped, the capacities of the cylinders and chambers variable individually with reciprocation of the piston, the improvement which resides in the combination therewith of a valve cage adjacent one end of the body having inta-ke Yand exhaust connections for power uidand an even number of passages communicating between the powerfluid connection and the' power cylinder remote from the cage, said passages spaced equally from a plane normal to the support and including the longitudinal axis of the bore and of equal cross-sectional area and valve means simultaneously controlling flow through said passages, whereby surging effects of iluid passing through the passages are substantially counterbalanced.

2. A pump as in claim l wherein the intermediate pump chambers each have ports to establish communication between both the chambers and a source of huid to be pumped and a discharge for pumped. uid, said ports having equal areas similarly disposed on each side of a p-lane normal to the support and including the longitudinal axis of the bore, whereby the forces produced by surging of fluid through the ports does not tend to effect lateral movement or rotation of the pump.

3. A. pump as in claim 1 wherein the body is a casting with said-fluid passages formed therein.

e. In a fluid actuated pump having a cast body with a cylinder bore, means including a double element piston and packer within the bore dividing it into two power cylinders at the ends of the piston and intermediate chambers for fluid to be pumped, the capacities of the cylinders and chambers variable individually with reciprocation of the piston, the improvement which resides in the combination therewith of power iiuid passages formed in the body communicating with the ends of the cylinders, said passages extending through one end of the body and adapted to supply power fluid to the piston and to an auxiliary power attachment.

5. A fluid actuated pump comprising a cast body with a cylinder bore and a support, means including a double element p-iston and packer within the bore dividing into power cylinders the ends of the piston and intermediate' chambers for fluid to be pumped, the capacities of the cylinders and chambers variable individually with reoiprocation of the piston, an auxiliary cylinder housing removably mounted on one end of the body with a bore axially aligned with the bore of the body, a second piston reoipr-ocally mounted in the bore of the housing and rigidly interconnected with the iirst piston, and passages communicating with the cylinders for supplying and exhausting power iiuid to and from the cylinders on corresponding sides ofy the pistons simultaneously, the passages for supplying power iluid to the auxiliary cylinder being even in number and provided in the castbody spaced equally from a plane normal to the pump support and including the longitudinal axis of the bore, said passages each being of. equalcros's-s'ectional area.

6. The pump of claim 5 wherein the auxiliary cylinder housing is a casting and has passages for supplying power fluid thereto communicating with the passages for this uid formed in the body, the passages in the auxiliary cylinder housing also being spaced equally from a plane normal to the pump support and including the longitudinal axes of the body and auxiliary cylinder housing bores, and each being of equal cross-sectional area.

'7. A fluid actuated pump comprising a body with a cylinder bore therein, a double element piston operably mounted within the bore to provide power cylinders at each end or" the piston with pumping chambers therebetween, a pressure booster including a cylinder with a bore axially aligned with the body bore, a plunger within the booster bore rigidly interconnected with the piston, the active area of the plunger being small relative to that of the power faces of the piston,

means for selectively supplying iiuid to be pumped to the pumping chambers and the booster cylinder and operable discharge connections from said pump chambers and booster cylinder whereby the pump may be selectively operated as a high volume and a high pressure pump.

8. In a iiuid actuated pump having a cylinder with a piston operably mounted therein to provide power cylinders and chambers for fluid to be pumped, a pressure booster including a second cylinder co-axial with the first cylinder, a plunger reciprocally mounted within the second cylinder andrhaving a'rigid connection with the piston, valve controlled ports for the second cylinder providing for alternate intake and exhaust of fluid to and from the cylinder on both sides of the plunger dependent upon the direction of travel of the plunger, reservoirs for iluid to be pumped haring ports communicating with the chambers of the first cylinder, a common inlet connection and common exhaust connection for the reservoirs, a conduit for supplying fluid to be pumped to the intake connection and the intake ports of the second cylinder, and means for selectively placing the intake and exhaust connections for the reservoir in communication whereby the unit serves as a high volume pump with said intake and exhaust connections out of communication and as aV high pressure pump with said connections in communication. Y

9. A pump as in claim 8 wherein a discharge line communicates with the exhaust connection for the vrservoirs and the exhaust ports of the second cylinder and has a back pressure check valve therein intermediate said points of comf munication.

10. In a fluid actuated pump having a cylinder with a piston operably mounted therein to provide power cylinders and chambers for uid to be pumped, a pressure booster including a second cylinder co-axial with the rst cylinder, a plunger reciprocally mounted within the second cylinder and having a rigid connection with the piston, valve controlled ports for the second cylinder providing for alternate intake and exhaust of iiuid to and from the cylinder to supply fluid to the cylinder on the suction side of the plunger and to exhaust fluid from the cylinder on the compression side of the plunger, reservoirs for fluid to be pumped having ports communicating with the chambers of the rst cylinder, a common inlet connection and common exhaust connection for the reservoirs, a conduit for supplying uid to be pumped to the intake connection and the intakeports of the second cylinder, a

pipe communicating between the intake and ex-y haust connections for the reservoirs and a valve controlling iiow through said pipe whereby the unit serves as a high volume pump with said intake and exhaust connections out of communication and as a high pressure pump with said connections in communication.

11. In a fluid actuated pump having a cylinderv with a piston operably mounted therein to provide power cylinders and pump chambers, a pressure booster including a second cylinder co-axial with the first cylinder, a plunger reciprocally mounted within the second cylinder and having a power transmitting connection with the piston, valve f controlled ports for the second cylinder providtake connection and the intake ports of the second cylinder, a discharge line communicating with the exhaust connection and the exhaust ports with a back flow check valve between the exhaust connection and the exhaust ports, a connection between the intake and exhaust connections for the reservoirs, a valve in said connection and a regulator for said valve, said regulator responsive to the pressure of said discharge line and operative to close said valve in said pipe when the discharge pressure is less than a predetermined amount and higher than a greater predetermined amount and to open said valve when the discharge pressure is intermediate said predetermined amounts.

12. A fluid actuated pump comprising a low pressure section and a high pressure booster section, said low pressure section having a cylinder with a piston operably mounted therein to provide power cylinders at both ends of the piston with two intermediate pumping chambers and common intake and exhaust ttings for the pump chambers for separately and alternatively supplying fluid to be pumped thereto, said booster section including a cylinder with a piston therein, means for actuating the piston, said piston, cylinder and actuating means so proportioned as to be capable of developinga high pressure relative to that of the low pressure section, a supply line communicating with the intake fitting of the low pressure section and having an operable valve controlled connection with the booster. cylinder, a discharge line communicating with the exhaust fitting of the low pressure section and having an operable valve controlled connection with the booster cylinder, a back flow check valve in the discharge line between the sections,

Y.and means responsive to the pressure in the discharge line downstream from the check valve for placing the exhaust and intake fittings in communication with one another when the discharge line pressure downstream from the check valve exceeds a predetermined low pressure but is less than a greater predetermined pressure.

13. A combination as in claim 12 wherein the pressure responsive means includes a valve and a regulator in which the regulator is adjustable as to its maximum pressure for closing the valve.

14. A fluid actuated pump assembly comprising a low pressure section and a high pressure booster section; the low pressure section having pump chambers and intake and exhaust fittings, said fittings each having separate valve connections with each pump chamber; the booster section having low volume capacity relative to the low pressure section and valved intake and exhaust ports for fluid to be pumped; a common discharge line connected to the exhausts of both pump sections with a back pressure check valve in the discharge line intermediate its connections to the pump sections; a connection between the intake and exhaust iittings of the low pressure section and a valve for the connection, a regulator for the valve responsive to the pressure in the discharge line downstream from the check valve for closing the valve when the discharge pressure in below a predetermined low pressure and exceeds a predetermined high pressure and to open the valve when the discharge pressure is an intermediate amount.

15. A luid actuated pump comprising a low pressure section and a high pressure booster section, the low pressure section including a cylinder, a double element piston therein dividing it into power cylinders at the ends of the piston and intermediate pumping chambers, said booster section having a pump cylinder with a piston therein, a power transmitting connection between the pistons of both sections whereby actuation of the low pressure piston actuates the booster piston, means for selectively' supplying and discharging iiuid to be pumped to the pump chambers of both sections separately, and means for supplying and discharging power fluid to the power cylinders of the low pressure section to reciprocally drive the double element piston therein.

16. A iiuid actuated pump comprising a low pressure section and a high pressure booster section, the low pressure section including a cylinder, a double element piston therein dividing it into power cylinders at the ends of the piston and intermediate pumping chambers, said booster section having a pump cylinder with a piston therein, a power transmitting connection between the pistons of both sections whereby actuation of the low pressure piston actuates the booster piston, means for selectively supplying and discharging fluid to be pumped to the pump chambers of both sections separately, means for supplying and discharging power fluid to the power cylinder or the low pressure section to reciprocally drive the double element piston therein, and means toI selectively introduce and exhaust power fluid to the pump chambers alternately whreby corre-- sponding faces cf both elements of the piston of the low pressure section may be simultaneously exposed to power iluid to increase the pressure that may be developed in the booster section when fluid to be pumped is supplied to the booster section.

17. A fluid actuated pump comprising a pump section including a cylinder, a double element piston therein dividing it into power cylinders at the ends of the piston and intermediate pumping chambers, means for selectively supplying and discharging fluid to be pumped to the pump chambers, means for supplying and discharging power fluid to the power cylinder to reciprocally drive the piston and means to selectively introduce exhaust power uid to the pump chambers alternately whereby corresponding faces of both elements of the piston may be simultaneously exposed to power fluid whereby the section may be selectively used as a pump or a power unit.

18. A fluid actuated pump comprising cylinder' means with piston means therein to provide power cylinders and low pressure pump chambers, means for alternately supplying and exhausting power fiuid to the power cylinders to actuate the piston means, valve controlled inlet and outlet ports for supplying and discharging fluid to be pumped to the pump chambers, a pressure booster including another cylinder of substantially smaller diameter than the pump chambers, a plunger reciprocally mounted within the second cylinder and having a power transmitting connection with the piston means, inlet and discharge ports for the booster cylinder with check valves controlling them providing for pumping of fluid upon each half cycle of the plunger, a main discharge conduit, the sole connections between the conduit and the pump being connections with the discharge ports of the pump chambers and booster cylinder, and means in the conduit preventing backflow from the booster discharge to the pump cylinders.

19. A iluid actuated pump comprising cylinder means with piston means therein to provide power cylinders and low pressure pump chambers, means for alternately supplying and exhausting power fluid to the power cylinders to actuate the piston means, valve controlled inlet and outlet ports for supplying and discharging iiuid to be pumpd to the pump chambers, a pressure booster including another cylinder of small diameter relative to the pump chambers, a plunger reciprocally mounted within the second cylinder and havimr a power transmitting connection with the piston means, inlet and discharge ports for the booster cylinder with check valves controlling them providing for pumping of fluid upon each half cycle of the plunger, a main discharge conduit, the sole connections between the conduit and the pump bLing connections with the discharge ports ci the pump chambers and booster cylinder, means in the conduit preventing backlow from the booster discharge to the pump cyL- inders, and fittings connected between the inlet and discharge ports for the pump chambers to selectively place thcm in communication for circulating iiuid.

20. A iiuid actuated pump comprising cylinder means with piston means therein to provide power cylinders and low pressure pump chambers, connection means for alternately supplying and exhaustinCr power iiuid to the power cylinders to actuate the piston means, valve controlled inlet and outlet ports for supplying and discharging uid to be pumped to the pump chambers, a pressure booster including another cylinder of small diameter relative to the pump chambers, a plunger reciprocally mounted within the second cylinder and having a power transmitting connection with the piston means, inlet and discharge ports for the booster cylinder with check valves controlling them providing for pumping of fluid upon each half cycle of the plunger, a main discharge conduit, the sole connections between the conduit and the pump being connections with discharge ports of the pump chambers and booster cylinder, means in the conduit preventingflow from the booster discharge to the pump cylinders, and means for selectively establishing communication between the pump chambers whereby they may be selectively rendered ineffective as a pump.

2l. ln a pump, a fluid operated actuator, cylinder means with piston means therein providingV a pump chamber, said piston means having apower transmitting connection with the actuator,

13 inlet and outlet ports for supplying and discharging uid to be pumped to and from the chamber, a booster cylinder of smaller area than that of the pump chamber with plunger means therein providing a booster pump chamber therein, said plunger means having a power transmitting connection with the actuator, means for supplying and discharging fluid to be pumped to and from the booster chamber, a common main discharge conduit, the sole connections between the conduit and the pump being connections with the discharge ports of the pump chambers and booster cylinder, check valve means in the conduit preventing backow of uid from the booster discharge into the low pressure discharge and means for selectively establishing communication between the inlet and outlet ports of the first chamber to establish circulation through the chamber and said ports.

ARTIE F. McFARLAND.

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

Number 14 UNITED STATES PATENTS Name Date Faulkner Jan. 17, 1899 Tuma Sept. 24, 1912 Coyne Dec. 9, 1913 Nickol Nov. 23, 1915 Hoerbiger May 20, 1930 Glover May 17, 1932 Breese Oct. 30, 1934 Woods Mar. 5, 1935y Jordy Sept. 7, 1937 McMillan May 17, 1938 Mayer Aug. 27, 1940 Trautman June 1, 1943 Turner Oct. 26, 1943 Tucker et al Dec. 7, 1943 Nicol Jan. 16 1945