US1909493A

US1909493A - Rodless pump

Info

Publication number: US1909493A
Application number: US559363A
Authority: US
Inventors: Granville S Knox
Original assignee: Individual
Current assignee: Individual
Priority date: 1931-08-26
Filing date: 1931-08-26
Publication date: 1933-05-16
Anticipated expiration: 1950-05-16

Description

G. S. KNOX RODLESS PUMP May 16, 1933.

Filed Aug. 26, 1931 7 Sheets-Sheet l Inventor dllameys G. S. KNOX RODLESS PUMP May 16, 1933.

Filed Aug. 26, 1951 7 Sheets-Sheet 2 G. S. KNOX ROBLES S PUMP May 16, 1933.

7 Sheets-Sheet 3 Filed Aug. 26, 1931 G. S. KNOX RODLESS PUMP May 16, 1933.

Filed Aug. 26, 19 1 7 Sheets-Sheet 4 May 16, 1933. G s KNOX 1,909,493

RODLES S PUMP Filed Aug. 28, 1931 7 Sheets-Sheet 5 Attorney.

7 Sheets-Sheet 6 Inventor May 16, 1933.

G. s. KNOX I RODLESS PUMP Filed Aug. 26, 1931 7 Sheets-Sheet 7 I72 ventor AlforneyS Patented May 16, 1933 PATENT OFFICE GBAfiVILLE S. KNOX, F LQS-ANGELES, CALIFORNIA RonLEss 'PUMP Application filed at ustzs, 1931. Serial No. 558,363.

This invention relates to well pumps and, more particularly, to an oil well pump adapted 'to' be positioned in the bottom of an'oil well and actuated by a hydraulic motor unitary therewith, which is operated by fluid transmitted thereto under high pressure through an inner pipe or tube extendingdown through the-well casingfrom the surface,

Fluid operated,or' rodless, pumps of this type are advantageous in that they eliminate the'necessity of mechanically operating the pump plunger from theIsurface' by sucker rods extending down through 1 the casing. Pumps employing sucker rods have serious defects, one of which is that they are entirely impracticable in extremely deep wells because of the weight of the rods,:and many attempts have been made to design satisfactory rodless flpump's employing a fluidoperated motor positioned in the bottom of the well, and numerous patents have issued on such devices.

Heretofore, to the best of my knowledge, none ofthese prior patented pumps have been 5 entirely satisfactory, some of them failing because of unsound mechanical design, others soon wearing out due to their design permitting the entry of sand from the pumped oil into the motor mechanism, and others becom- 0 ing jammed or locked while in the well due to the presence of gas or sand in the oil.

A broad object of this invenion is to provide a fluid-operated pump that is operative under all conditions under which it may be used, that is mechanically strong and rugged, and that will not soon be rendered inoperative by natural and unavoidable wear occasioned by sand in the pumped fluid.

This invention is an improvement on the 40 pump disclosed in United States Patent No. 1,562,688, issued to R. R. Crum on November 24th, 1925. It resembles the Crum pump in bet it comprises a pump and a motor positioned one above the other. with the piston 5 of the pump connected to the piston of the motor by a piston rod having associated therewith a valve mechanism. In both my pump and that of Crum. the piston assembly is reciprocated up and down by alternately admitting high pressure fluid to the upper and the lower sideof the motor piston, the admission of this fluid being controlled hya'valve mechanism which is operable into tjwo positions. The valve itself 'isrii'oved into-the respective positions by high pressure fluid applied to opposite facesthereon under th'e cone trolo'f an auxiliary valve incorporated in the piston rod.-' Thfusfin'both pumpsfiwhenthe motor piston isi'n its'low er' position, the "auxiliary valve. mechanism admits high pressure fluid to a face on the main 'v'alvetomove the latter into such positionas to admit high pressure fluid into the lowerend' bf the cylinder; thereupon the piston moves up. I As it reaches its uppermost position it actuates the auxilia'ry valvefto admit high pressure fluid to the opposite side o f thelma'in-va'lve', thereby moving the latter into its opposite position whereby it admits high'p'ressure fluid to the upper end-of the cylinder, whereupon the piston moves down and-completes a cycle of operation. 1 f

It is characteristic ofboth my..p'ump and that of Crum that the mainvalve is moved and held in its various positions solely by hydraulic pressure'acting against the ends thereof. In the .Crumpump, the maintenance of this hydraulic pressure is dependent upon a tight seal between the valve and its containing walls, since, if fluid can leak past the valve, the latter may, due to the action of gravity or other cause, move away from the position in which it admits'high pressure fluid to the motor, thereby permitting the motor piston to stop before completing its stroke, under which condition it may be permanently stalled. An important featureof my invention is a valve design that, first, permits the valve to move a considerable distance away from its end position without cutting 01f the flow of high pressure fluid to the motor cylinder, and, second, that reduces the possibility of high pressure fluid leaking past the sealing surfaces of the valve to or from the operating faces thereof, by interposing low pressure chambers between the high pressure chamber and the operating faces of the valve.

Another disadvantage of the Crum pump is that the piston and auxiliary valve asso- 10.

.. of the motor.

ciated therewith may commence to move on the reverse stroke before the main valve has fully uncovered the valve ports to said piston. This would cause fluid to flow to the motor piston very slowly, and should the valve drop ack any appreciable amount, the flow to said piston would be entirely shut oil, thereby preventing thelatter from ever completing its stroke and thereby stalling the pump. In

accordance with the present invention, by an ingenious application of the pressure fluid to the main valve, and to the motor piston, I insure that the valve will complete its stroke before the piston travels an appreciable distance thereby fully uncovering the valve ports and thus eliminating possibility of stalling.

In the Crum pump, the pump cylinder is mounted below the motor cylinder. I have found that by inverting the pump cylinder and mounting it above the motor cylinder, I can reducethe possibility of the pump becoming inoperative due to gas-lock, a condition oftenencountered with pumps used in wells carrying a high percentage of gas in the oil. Furthermore, this form of construction confines the well fluid, which ordinarily contains abrasive material, to the upper end of the pump and away from the fluid-actuated motorjf The design of my pump allows the well fluidto flow into my pump on both strokes of the pump piston. This is desirable as it'reduces the maximum velocity with which the well oil flows into the pump and aids in keeping free gas out of the pump, as the said gas will have a tendency to rise upward past the entrance port to the pump case when the oil is flowing into the pump cylinder at reduced speeds. Free gas in the well fluid isfurther prevented from entering the pump cylinder by causingthe well fluid to flow downwardly vbefore entering the cylinder. The gas, being lighter than the oil, will, therefore, rise to the top and return to the well, while the oil settles to the bottom and enters the pump cylinder.

In the Crum patent, the main valve has no mechanical connection with the moving parts The operation of the valve is entirel dependent upon the fluid pressure applie thereto. In my pump, I mount the main valve mechanism concentrically about and in contact with the piston rod and cause the valve and piston rod to move in the same direction on each stroke, the valve moving first to its extreme up or down position and the piston rod following in the same direction immediately thereaftor. l/Vith this arrangement, the unavoidable friction between the piston rod and the valve mechanism always tends to move the valve mechanism in the proper direction to maintain it in its desired position.

Other novel and advantageous features of this invention will be apparent from the following description, which refers to the drawings, in which Fig. 1 is an elevational view, partly in section, showing my pump in entirety in a well casing;

Figs. 2, 3, 4., 5 and 6 are enlarged detail sectional elevational views of the pump showing its construction, Fig. 2 showing the upper end of the pump, and Figs. 3, 4, 5 and 6 showing consecutively lower portions thereof;

Fig. 7 is a sectional elevational view of a portion of the pump taken in the plane VIIVII of Fig. 3;

Fig. 8 is a. sectional elevational view of the same longitudinal portion of the pump disclosed in'Fig. 4, but in a plane at right angles to the plane of Fig. 4;

Fig. 9 is a sectional elevational view in the plane IXIX of Fig. 5;

Figs. 10, 11 and 12 are horizontal, sectional views taken in the planes XX, XIXI, and XIIXII, respectively, of Fig.- 2;

Figs. 13 and 14 are horizontal sectional views .in the planes XIII-XIII and XIVXIV, of Fig. 3;

Figs. 15 and 16 are horizontal sectional views taken in the planes XVXV and XVIXVI, of Fig. 4:;

Figs. 17 and 18 are horizontal sectional views taken in the planes XVII-XVII and XVIII-XVIII, of Fig. 5;

Fig. 19 is a horizontal sectional view taken in the plane XIXXIX, of Fig. 6;

Figs. 20, 21, 22, 23, 24 and 25 are schematic diagrams illustrating the operation of my pump.

A complete understanding of my invention can be most readily obtained by first following through its operation with reference to the schematic diagrams of Figs. 20 to inclusive, and thereafter explaining the actual construction of the pump as disclosed in Figs. 1 to 19, inclusive.

Referring to Fig. 20, I have shown a section of well casing 1. Positioned within the well casing and substantially at the bottom of the well, is my pump which comprises an outer shell or frame 2 attached to the lower end of a pipe 3 which extends up through the casing to the top of the well and serves as the passage for pumped oil and for exhaust oil from the hydraulic motor which constitutes the prime mover for the pump. Attached to the frame 2 by joining members 4 is a cylinder block 5, which has formed in its upper end a pump cylinder 6 and in its lower end a motor cylinder 7 A pump piston 8 in the pump cylinder 6, and a motor piston 9 in'the motor cylinder 7, are rigidly connected together by a piston rod 10 which is slidingly mounted in the cylinder block 5 at a point 11 immediately below the pump cylinder 6 and at a point 12 immediately above the motor cylinder 7. The cylinder block 5 is provided with an enlarged passage 13, surrounding the piston rod 10, positioned substantially midway between the pump cyl- 5 inder 6 and the motor cylinder 7, and a sliding valve 14, is mounted in this passage con: centrically about the piston rod 10. Various ports are provided for the flow 'of fluid to and from the valve chamber 13, the pump cylinder 6 and the motor cylinder 7 the functions of these various passages will be made clear in the explanation of the operation of the device.

A pipe 15 is positioned concentrically within the exhaust pipe 3 and like the latter pipe extends to the surface where it is connected to a pump for supplying a continuous flow of operating fluid (preferably clean oil) for the operation of the pump motor.

0 Assume that, as shown in Fig. 20, the motor piston 9 and the main valve 14 are in their lowermost positions, that the space between the pump 2 and the casing 1 is filled with well oil, and that operating oil is being continu- 5 ously forced down through the inner pipe 15.

Oil from pipe 15 must pass down through a passage 16 and througha port 17 into that portion of the valve chamber 13 between valve shoulders 19 and 20. There is an open- 3 ing from this portion of the valve chamber through a port 22 and a pipe 23 into the upper end of motor cylinder 7. However, since the motor piston 9 is at the bottom of its stroke it can move no further and no additional oil can flow into cylinder 7. Therefore, the oil being forced into the valve chamber through port 17 must pass through a port 24 into a passage 25 within the piston rod 10 and out through a port 26 into that portion of the valve chamber 9 below the main valve 14. Since oil is continuously flowing down through pipe 15, the pressure of'this oil exerted against the lower face of the valve 14 forces that valve upward to the position shown in Fig. 21. As the 5 valve 14 moves up, oil in the valve chamber above the top of the valve is exhausted through a port 30 in the piston rod, thespace between the

shoulders

18 and 19 on the valve and a port 31, through a pipe 32 into a cham- 3 her 33, and thence up into the exhaust pipe 3 to the top of the well.

High pressure oil passing from passage 16 through port 17 still enters the valve chamber 13 between the

shoulders

19 and 26 on 3 valve 14. However, in the new position of the valve, (referring now to Fig. 21), port 22 is cut off from port 17 by valve shoulder 20 and a new port 27 has been uncovered by the upward movement of shoulder 19. The oil 3 being continuously'forced through port 17 being no longer able to escape through the passage 25 in the piston rod, for the reason that the valve 14 has reached the upper end of its stroke, must flow through port 27, a

5 passage 28, and a port 29 into the lower end of cylinder 7. It thereupon forces the piston 9 upward. As the piston 9 moves upward,

ton 9, it must move upward therewith, and

the oil in the pump cylinder above pump piston 8 is therefore forced out past a check valve 35 into chamber 33 and thence up through pipe 3. As the pump piston 8 moves up, it tends to create a vacuum in the space therebelow and oil flows in from the well through a port 36 to occupy this space.

Referring now to Fig. 22, the motor piston and pump plunger have reached their uppermost posit-ions, and the space below the motor piston 9 is filled with high pressure oil from pipe 28. Oil, of course, is continuously flowing down through passage 16 into that portion of the valve chamber shoulders 19 and 20. This oil can no longer escape through port 27 and passage 28 because the motor piston 9 has reached the upper limit of its stroke. However, the upper movement of the piston rod has brought the lower end of passage 25 above valve shoulder 20 so that the oil flowing in through port 17 can now escape through passage 25 into the end of the valve chamber above the valve 14. This pressure forces valve 14 down to its lowermost position, the oil in-the valve chamber below the valve being exhausted through a port 37 into the exhaust pipe 32. The pump is now in the condition shown in Fig. 23.

Referring now to Fig. 23, the valve 14, being in its original position as shown in Fig. 20, the-fluid entering port 17, being unable any longer to escape through passage 25 to the space above the valve .14, escapes through port 22 and pipe 23 into the top of cylinder 7, where it acts against the top of motor piston 9 and forces the latter down to its lowermost position. As the piston moves down, the oil in the cylinder below it, is exhausted through pipe 28, port 27, the space in the valve chamber between valve shoulders 18 and 19 to the port 31 into the exhaust pipe 32. As the pump piston 8 moves downward with the motor piston 9, the well fluid passes through the port 36 and past check valve 38 in the pump piston to fill the space in the pump cylinder above the pump piston. Of course during this down stroke of the pump piston the outlet check valve is maintained in closed position by the pressure of the exhaust oil in chamber 33. The pump is now in the condition shown in Fig. 20, and a cycle of operation has been completed.

The above description outlines in a general manner the operation of my pump. To give a full understanding as to just why the pump must always operate as set forth above,

further explanation must be made of some of the operations that take place.

In discussing the operation of the pump from the initial condition shown in Fig. 20,

' it was stated that valve 14 completed its upward stroke before, the motor piston 9 began its upward stroke. However, unless special provision was made to prevent such action, the motor piston 9 would begin to move upward as soon as the lower edge of valve shoulder 19 cleared the lower edge of port 27. Thus, referring to Fig. 24, the valve is shown arrested in its upper movement,

with the lower edge of valve shoulder 19 above the lower edge of port 27. Thus there is an open passage for operating fluid to flow from the passage 16'through port 17 up through the valve chamber and below the f0 1" the reason that more pressure is required to lift the motor piston than is required to lift the valve 14 and the pressure of the operating fluid in passage 28 and below motor piston 9 cannot rise above the pressure required to move valve 14 until the latter has reached the upper limit of its stroke.

That a greater pressure is required to move the pistons than to move the valve, Will be apparent from an analysis of the forces acting on the valve and the motor piston, respectively:

Considering, first, the valve 14, it will be noted that pressures exerted on the valve by the fluid admitted to the spaces between the

shoulders

18, 19, 20 and 21, may be disregarded because any pressure applied at these points must exert equal and opposite forces on the valve. Therefore, the only forces tending to move the valve are the forces acting on the lower and upper ends, respectively, of the valve. With the valve in the position shown in Fig. 24, the high pressure fluid admitted through port 17 and passage 25 acts directly against the lower face of the valve. At the same time, the upper end of the valve is exposed to the pressure of the oil in the exhaust pipe 32 through the port 30 in the piston rod. Since the upper and lower ends of the valve are of equal area, the pressure of the operating fluid flowing in through passage 16 will move the valve upward if the pressure of the operating fluid is sufliciently greater than the pressure of the exhaust fluid in pipe 32 to overcome the weight of the valve and its friction against the wall of the valve chamber and against the piston rod.

Summarizing, the operating and exhaustfluids operate against faces of equal areas on the opposite ends. of the valve 14 and the valve will move as soon as the difference between the pressures of the operating and exhaust valves is of sufiicient magnitude to overcome the weight and friction of the valve.

Analyzing the pressures exerted on the piston assembly, I find that the lower end of the motor piston is exposed to the pressure of the operating fluid and that the upper end of the pump piston, which is of substantially the same area, is exposed to the pressure of the exhaust fluid. If these were the only pressures acting on the piston assembly, the latter,- like the valve 14, would move upward as soon as the difference between the pressures of the operating and the exhaust fluid was of suflicient magnitude to overcome the weightand the friction of the pistons. However, in addition to the pressures acting onthe lower face of the motor piston and the upper face of the pump piston, there is the pressure of the exhaust fluid acting upon the upper face of the motor piston.- Thus, in Fig. 24, the exhaust fluid in pipe 32 is connected through port 34, through that portion of the valve chamber between valve shoulders 20 and 21, and through port 22 and pipe 23 to the upper end of the motor cylinder 7.

It should be noted that'pressure of the exhaust fluid acting on the upper side of motor piston 9 is not counter-balanced by the pressure of the well fluid acting on the lower side of pump piston 8 because the static head of the well fluid is alwaysless, and generally very much less, than the static head of the exhaust fluid. It is obvious that this condition must exist, as otherwise the well would flow naturally and would not need to; be pum d.

It will be seen from the foregoing facts that although the operating and exhaust fluids exert pressure in opposite directions on equal areas of' the valve 14, the operating fluid is acting on a smaller area of the piston assembly than is the exhaust fluid, since the operating fluid acts only on one face of the motor piston, whereas the exhaust fluid is actin on the other face of the motor piston and a so on the upper face of the pump piston. It follows that the operating fluid must have a definitely higher pressure to move the piston assembly than to move the valve 14, and since operating fluid is flowing at 311111- form rate through passage 16, ports 17 and passage 25, its pressure cannot rise above that necessary to move the valve 14 untilfthe.

The samecondition outlined above prevails'on the down strokeof the valve. Thus,

and the passage 25 to the upper end of the valve chamber, whereas the only. force acting upward on the valve isth'at due to the exhaust fluid below the valve which is connected through ports, 37 in the piston rod, that portion of the valve chamber between

shoulders

20 and 21, and the'port 34, to the exhaust pipe 32.

While the valve 14 is"moving down, but has not yet quite completed its stroke, the only force acting downward on the pistons is the pressure of the operating fluid entering through port 17, the portion of the valve chamber between valve shoulders 19 and 20, port 22, and pipe 23 to the upper end of the cylinder '7, whereas the forces acting upward on the piston are those exerted by the pressure Qf'the exhaust fluid in pipe 32 which is connected through port 31, the portion of the valve chamber between valve shoulders 18 and 19, port 27, passage 28 to the lower end of cylinder 7, where it. is impressed on the lower face of motor piston 9.

It will be noted that during the down stroke the exhaust fluid exerts no pressure on the lower side of the pump piston 8 because the check valve 38 is free to open and prevent the pressure on the lower side of the pump piston from rising above that in the space above the piston. However, the area of the upper side of the motor piston 9 is less than that of the lower side because of the presence of the piston rod 10. Therefore,

, the pressure of the operating fluid must be considerably greater than that of the exhaust fluid before the piston will move, because the operating fluid is acting on a smaller area of the piston than is the exhaust fluid. Therefore, until the valve 14: has completed its stroke, the pressure of the operating fluid will be insuflicient to exert suflicient force on the upper side of the motor piston 9 to overcome the pressure exerted by the exhaus. fluid on the larger lower face of the motor piston.

Any tendency of the valve 18 to move away from its end position during a piston stroke is also resisted by friction between the piston rod 10 and the valve, since the piston rod, when in motion, always moves in the same direction in which the valve has last moved.

Since, as outlined above, the valve 14 will ordinarily complete its stroke regardless of the fact that the high pressure fluid may be simultaneously applied to move the piston,

.it is possible to so dimension the

ports

27 and 22 that they open to admit high pressure fluid to one end or the other of the piston some time before the valve 14 reaches the end of its stroke. This is advantageous in that it is possible for the valve to drop back a considerable distance from its end osition without shutting off the flow of flui to the motor piston.

Referring, now, to Fig. 21, with the valve 14 in its uppermost position, operating fluid is supplied through passage 16, port 17, port 27 and passage 28 to the lower end of cylinder 7. Therefore fluid flowing into the bottom of cylinder 7 will raise the piston 9. As the piston moves upward there will be a period during which the space below the valve 14: will be disconnected from the high pressure chamber between

shoulders

19 and 20 on the valve, and the space above the Valve will be disconnected from the exhaust passage 31. During this interval the maintenance of the valve in its proper position is dependent upon a proper seal between the

shoulders

18 and 21 on the valve and the cylinder walls. If this seal is imperfect as the result of wear there may be a leakage of fluid therepast which will permit the valve to settle away from its end position. The possibility of the valve settling back would be increased if there were any opportunity for high pressure fluid from the port 17 to leak past the valve shoulders 19 and 18 to the upper end of the valve. With my construction, however, there is no possibility of high pressure fluid flowing from the central valve chamber bounded by

shoulders

19 and 20 to either end of the valve through the valve clearances, because the chambers bounded by

shoulders

18 and 19 and by 20 and 21, respectively, are always connected directly to the exhaust passage 32. Therefore, the pressure below the shoulders 18 and above shoulder 21 can never exceed the pressure of the exhaust fluid in exhaust passage 32. Any leakage of high pressure fluid

past shoulders

19 or 20 will pass out as exhaust fluid through port 31 or port at. g

It is a characteristic of some rodless pumps, notably the pump disclosed in the aforementioned Crum Patent, 1,562,688, that fluid to actuate the main valve is admitted to the valve face through cooperating ports in the piston rod and the stationary guide surrounding the rod. With this construction, fluid to shift the main valve is only supplied while the pump piston is in one end position, for the reason that as soon as the pump piston moves away from its end position the port in the piston rod moves away from its cooperating port in the stationary framework, thus closing the passage supplying operating fluid to the valve.

This feature is objectionable because if, for any reason, the pump piston moves away from its end position before the main valve has completed its stroke, the main valve will be stalled before reaching its end position, in which the ports supplying fluid to the motor piston are fully opened. In accordance with my invention, I overcome the above difliculty by supplying fiuid to shift the mam valve throug ports in the piston rod WhlCll reglster with chambers in the main valve. Thus, referring to Fig. 24, assume that the main valve. is moving upward but has not yet reached the upper limit of its stroke. Operating fluid to move the valve is of course being supplied through port 17, the valve chamber between

shoulders

19 and 20, port 24, passage 25 and port 26 in the piston rod to the lower face of the valve. It will be readily seen that since fluid is being supplied to the passage 25 in the piston rod through port 24, which opens into the valve chamber between

shoulders

19 and 20, the piston rod 10 can move up a considerable distance without closing the port 24 because of the fact that it receives fluid from the moving valve chamber instead of from a port in the stationary structure of the pump. The same action occurs with respect to the discharge port 30 in the piston rod since it exhausts oil from above the main valve into the valve chamber behas been encountered in pumping wells carrying very large amounts of gas. My pump is particularly well adapted to handle oil containing gas, and the particular structural features which make it workable with gas will now be described.

Referring'to Fig. 20, it will be observed that the passage 36, leading from the well into the lower end of the pump cylinder 6, is inclined downwardly from its outer opening into the cylinder'block. Since gas is lighther than oil this vertically extending passage encourages oil to flow into the pump while retarding the flow of gas therein. Assume, however, that some gas enters passage 36 and the lower end of the pump cylinder 6, on the up stroke of the piston 8. On the next down stroke of the piston this gas will be exhausted past the check valve 38 into the cylinder space above the piston so that at the beginning of the next up stroke of the piston the cylinder 6 is partially filled with gas. Since this gas is at the pressure of the well fluid in the casing 1, it will be at a substantially lower pressure than that of the exhaust fluid in chamber 33 which is exposed to the static head i of the fluid in pipe 3 extending to" the surface. Therefore the downward pressure exerted on the pump piston 8 may be substantially less than that of the exhaust fluid in space33, and the downward force exerted on the pump piston, together with the downward force exerted on the top of the motor piston 9, may be less than the force exerted fluid on the under side of piston 9. Under these conditions, it'is possible that less pressure of operating fluid will be re uired to lift the pistons than is required to 11ft the valve 14, under which conditions the piston would tend to begin its upward movement as soon as the valve lifted sufliciently for shoulder 19 to clear the lower edge of port 27. It is conceivable that the rush of fluid through port into the motor cylinder 7 might be rapid enou h to reduce the ressure o the operating uid to a value lnsuflicient to continue lifting the valve 14. The rising piston rod 10 then might carry port 26 above the lower shoulder 21 of the valve, thus cutting off the flow of operating fluid thereto and preventing the valve from ever reaching the upper end of its stroke. To reduce the possibility of such an occurrence, the lower portion of the port 27 is made of reduced area, as indicated at 39 in Fig. 20. This reduces the area of the passage to the motor cylinder when the valve first opens and sufliciently restricts the flow of operating fluid therethrough to pre-, vent the pressure of the operating fluid falling below that necessary to continue lifting the valve to its position of full opening.

However, this restricted port area 39 supplies fluid slowly to cylinder 7 and insures that the motor piston 9 will be carried to the upper limit of its stroke should the main valve 14 settle back from its upper end position so as to close themain part of port 27.

The possibility of my pump becoming inoperative because of gas-lock is further reduced because of the fact that the pump is po- Sitioned above the motor with the piston rod extending below the piston instead of above. It has been customary in the past in designing rodless pumps to position the pump-below the motor. In order to understand how the construction of my pump reduces the possibility of gas-lock, it will be necessary to discuss the operation of the usual type of pump in which the pump is ositioned below the motor and the pump fluid is exhausted from the pump cylinder on the down stroke of the piston.

It is the general practice in oil well pumps to form the pump piston from a tubular piece which is ground to fit the pump cylinder with a clearance of from .002 to .004 of an inch.

In the ordinary pump the piston on its down the operating."

ton moles upward on the next stroke, the pressur below the piston is reduced while the gas directly above the piston will be at a very high pressure due to the hydrostatic pressure of the column of fluid in the exhaust tubing extending tothe surface. In deep wells, this pressure may be 2,000 pounds or more per square inch. It is practically impossible to maintain a sufficiently tight seal between the pump piston and cylinder to restrain this high gas pressure and consequently the gas rushes through the clearance between the piston and cylinder wall into the cylinder below the piston where it expands and prevents theadmission of well oil (which is at relatively low pressure) into the cylinder. At the next down stroke the as in the cylinder is compressed between t e check valve at the lower end of the cylinder and the pump piston, but it may not be compressed sufliciently to reach the pressure existing above the piston and to open the check valve in the piston. Therefore the piston may continue to work against this gas cushion without pumping any oil and the pump is said to be gas-locked...

Inmy pump, the oil is exhausted from the cylinder on the up stroke of the piston, passing through the check valve in the cylinder head, and on the down stroke oil from the well is admitted to the 'pump cylinder through the check valve in the hollow piston. Therefore, the upper side of the piston is not at all times exposed to the full pressure of the column of fluid in the exhaust tubing leading to the surface and there is less opportunity for gas to be forced past the piston through the clearance between the piston and cylinder wall. The design of my pump also permits practically all of the space within the pump cylinder to be exhausted, thereby reducing the possibility of accumulating suflicient gas in the cylinder at the end of the up stroke of the piston to prevent the opening of the check valve in the piston on the subsequent down stroke.

Under normal conditions, the pump will operate continuously as has been outlined, since means is provided for causing the valve to positively complete its stroke before the piston assembly completes its stroke and although the valve may settle back slightly from its end position while the piston is completing its stroke, such settling back will not 7 cut off the flow of fluid to the piston.

However, it is conceivable that while the pump is being installed the valve and pistons may be iolted into a position in which operating fluid would not be admitted to move either the valve or the piston. In other words, the pump would be on dead center.

In Fig. 25, the motor piston and valve are shown in a dead center position. Thus the valve and motor piston are so positioned that portion of the valve chamber between valve shoulders 19 and 20, cannot escape therefrom, theports 24 and 26 in the piston rod being above and below

shoulders

19 and 20 and the

ports

27 and 22 in the cylinder block being closed by the valve shoulders 19 and 20. It will be seen that if either the valve or the motor piston is moved any appreciable distance a port will be brought into registration with the portion of the valve chamber between

shoulders

19 and 20 and the pump Wi I be restored to operating position. To make it possible to move the motor piston in such an emergency, I provide a passage 40 between the passage 16 and the passage 28 extending to the lower end of cylinder 7 with a check valve 41 therein and passage 42 containing a check valve 43 between exhaust passages 32 and the upper end of motor cylinder 7. No fluid is normally transmitted through these passages because the pressure of the operating fluid in, passage 16 is always equal to or greater than the pressure of the fluid in passage 28, thereby maintaining the check valve 41 closed and the pressure in the motor cylinder 7 above the motor piston 9 is always equal to, or greater than, the pressure in the exhaust passage 32, thereby maintaining the check valve 43 closed.

If and when. the pump becomes stopped on dead center, as shown in Fig. 25, it is restored to operative condition by reversing the flow of fluid in

pipes

3 and 15, that is, by reducing the pressure at the top of the well on the fluid in 'pipe 15 and increasing the pressure on the exhaust fluid in pipe 3., This over that in the operating fluid passage 16,

which pressure opensthe check valve 43 in passage 42 and the check valve 41 in passage 40, thus permitting a flow of fluid from passage 32 through passage 42 into the upper end of the motor cylinder 7 and a flow of fluid out of the lower end of motor cylinder 7 through

passages

28 and 40 into the passage 16. The pressure created in the upper end of cylinder 7, being greater than the pressure in the lower end of the cylinder, the piston 9 is carried downward, thus moving it off dead center and permitting it to function thereafter in the usual manner when pressure is againapplied to the fluid in pipe 15 and the pressure released on the fluid in the exhaust pipe 3. I

As there is usually more or less sand or other gritty substances mixed with petroleum as it occurs in the earth, a certain amount of such substances are present in the well oil and it is important that this material be kept out of contact with the moving parts of the pump. Of course it is impossible to keep sand or grit present in the well oil out of the pump cylinder. However, with my design operating fluid entering port 17, and that I am able to prevent the well oil, and any 139 gritty substances in suspension therein, from contacting with the moving parts of the motor and valve assembly.

Thus, referring to Fig. 20, the only portions of my unit in contact with well oil are 13 and the motor cylinder 7 and then out through the exhaust passage 32 into the chamber 33 where it mixes with the gritty well oil and passes to the surface therewith through pipe 3. Since there is a constant flow of-clean oil upward through exhaust passage 32, there is little or no possibility of gritty particles finding their way from the well oil in chamber 33 down through passage 32 and into the motor cylinder or the valve mechanism. The only other possible point of entry of gritting oil into the valve mechanism and cylinder is from the lower end of pump cylinder 6 down around the piston rod 10. The possibility of oil flowing in this direction is very slight for the reason that the pressure of the clean operating oil in the upper end of the valve chamber 13 is always equal to, or greater than, the pressure of well fluid in the lower end of pump cylinder 6. This is apparent because the oil in the upper end of the valve chamber is always either that of the operating fluid in passage 16, or of the exhaust fluidin passage 32, and the pressure of these fluids'is always greater than the pressure of the well fluid because of the static head produced in the

pipes

15 and 3 leading to the top of the well. In this connectionit should be noted that the port 30 inthe piston rod 10 is shown as passing above the lower end of the pump cylinder 6 in Figs. 22 and 23, when the 'pis-.

tons are in uppermost positions. This condition exists in the schematic diagrams constituting Figs. 20 to 25, because it was neces sary to shorten the pumpin these views to.

show the pump in entirety in a single view.

In the actual construction of the pump which will be described later with reference to Figs. 1 to 19, inclusive, the distance between the top of the valve chamber 13 and the bottom of the pump cylinder 6 is sufficiently great to prevent the ports 30 ever rising into the pump cylinder.

In order to reduce the possibility of well oil containing abrasive matter from passing through exhaust passage 32 and check valve 43 into the motor cylinder 7, when the pressure is reversed to move the pump off dead inder closing center, the reverse action is continued for only a short period of time. As pointed out, it is only necessary to move the motor piston a short distance to get it ofli dead center.

Although Figs. 20 to 25, inclusive, disclose accurately the operation of my pump, an actual pump designed exactly as shown would be impracticable because of the excessive space occupied by the pipes used to form the

passages

16, 28, 23 and 32, since these pumps are designed to be used in deep wells when the well casings are of restricted diameter and-in many cases may be less than five inches in diameter. An actual pump ,would, therefore, have to have an overall diameter sufficiently small to pass within a well casing. Under these conditions, unless the diameters of the motor and pump cylinders are reduced to extremely small dimensions, the passages for the-fluid outside of the cylinders must be so designed as to occupy very little radial'space.

A preferred design of pump, in which the limited radial space within the outer casing or frame 2 is used to best advantage, will now be described with reference to Figs. 1 to 19.

,Thus, referring to Fig. 2, the upper end of the outer shell of my pump comprises a 'tubular cap member 50 having inside screw threads 51 whereby it may be secured to the lower end of a string of pipe 3 serving as the thelatter extending substantially to the lower end of the pump where it screws onto a threaded block 56. A lower cap 57 is threaded onto the-lower ends of block 56. The wall of the pump cylinder is formed by a plurality of liners '58 which are maintained in alignment'by being clamped between an upper cylinder closing member 59 and a lower cylmember 60.- The member 59, which-contains a pair of check valves 35, is restrained againstupward movement with respect to the outer jacket, by a block 61 which rests against the upper end of cylinder closingmem'ber 59, and by a shoulder 62 on. the cap member 50. The lower cylinder closing member 60 forms the guide for the piston rod 10a and is also bul "1 several sections extending down to and abutting against the top end of the wall of the motor cylinder 7, which wall is composed of several sectional liners 66, the lower one of which abuts against block 56 which is screwed onto the lower jacket member 55.

The upper cap member 50, in addition to being threaded at its upper end for connection with the pipe 3, has an inner portion 68 threaded to receive the operating fluid pipe 15; The passages "leading from the two threaded

openings

51 and 68 in upper cap 50 to the various operating chambers of the pump will be followed through in detail later.

The pump piston represented as a solid structure in Figs. 20 to 25, is made up in the actual working model shown in Figs. 1 to 19, of a hollow sleeve 69 having an enlarged inner bore at the upper end thereof in which the check valve assembly 70 is mounted, the latter being secured in the end of the piston by a bushing 71 screwed into the end of the piston sleeve 69. The lower end of the sleeve 69 is secured to the upper end of the pump piston rod 10a by a bushing 72 screwed into the lower end of sleeve 69 which clamps a ainst a shoulder on the upper end of the piston rod 1001.

That portion of the piston rod containing the passage 25, comprises a hollow tubular section 105 which is screwed onto the lower end of the pump piston rod and onto the upper end of the motor piston rod 100. The motor piston comprises a hollow sleeve 73 which issecured at its upper end to the lower end of the piston rod 100 by a bushing 74 threaded into the top of the piston sleeve 73 which bears against a shoulder member 7 5 threaded onto the lower end of the piston rod 100, the lower end of the piston sleeve 73 being closed by a plug 76 which is threaded therein. i

The passages-leading from the inlet and

outlet pipes

15 and 3, respectively, comprise passages in the block 61, the upper cylinder closing member 59, the pump cylinder lining 58, the pump piston guide 60, the valve chamber lining 63, the motor piston rod guide 64, the lower motor piston rod guide section 65, the motor cylinder liner 66, and the spaces between the pump cylinder lining 58 and the outer shell 53 and the space between the motor piston rod guide 64 and the outer shell 55 or the space between the shell 66a surrounding the motor cylinder liner 66 and the outer shell 55.

Thus tracing the flow of operating fluid from the chamber 77, connecting with pipe, 15, there is a passage 78 formed in the upper pump cylinder closing member 61 which communicates with a passage 79 in the member As shown in Fig. 11, passage 78 is areuate in shape. Passage 79, formed in the upper cylinder closing member 59, which connects with passage 78, is of similar cross sectional shape and opens at its lower end into a passage 80 in the cylinder liner 58. This passage continues down through the cylinder liner 58 and the pump piston guide 60, and the valve cylinder lining 63 to port 17 shown in Fig. 4, opening into the valve chamber 13. The passage 28 of Fig. 20 connecting port 27 in the valve chamber with the lower end of the motor cylinder 7, may be traced in the actual pump structure as followsi Referring to Fig. 8, port 27 comprises two opposite openings in the valve chamber wall 63 which lead into a pair of

vertical passages

84 and 85 in the valve chamber wall 63. The cross sectional sha e of these passages is shown in Fig. 17, w ich cross section is taken in the plane XVII-XVII of Fig. 5, and Fig. 9, immediately below the coupling member 54, at which point pasages 86 and 87 connect them with the annular passage 88 formed between the spaced valve chamber liner 63 and the outer shell 55. Annular passage 88 is sealed at its upper end by the coupling member immediately thereabove, but it extends downward around the motor piston rod guide 64 to the motor cylinder liner 66 and thence I liner 66a and the outer shell 55, to the bottom of the cylinder where it connects with the interior of the cylinder through ports 89,

The connection between passage 40, containing check valve 41 and connecting

passages

16 and 28 in Fig. 20, may be traced in the actual design as follows: Referring to Fig. 4, passage 80 connects at plane XV-XV with a circumferentially directed passage 90 (referring to Fig. 15) which, (referring now to Fig. 8), connects with the upper slde of check valve 41 through passages 90a and 90b. The lower side of check valve 41 connects directly with passage 85 which is extended above the ports 27.

Passage 23, connecting port 22 with the upper end of the motor cylinder 7, is shown in Fig. 5, as comprising a assage extending vertically from port 22 dbwn through the valve chamber lining 63 to the motor piston rod guide 64 into the upper end of cylinder 7.

The passage 36, leading from the exterior of the pump into the lower end of the pump cylinder 6, comprises a concentric passage 36:; between the pump cylinder'liner 58 and the outer shell 53. Numerous openings 36?; are

provided in the outer shell 53 to permit well fluid to flow therethrough into passage 36a and a port 360 is provided in the pump cylinder lining 58 substantially at the bottom of the cylinder to permit the entrance of well fluid from the concentric passage 36a into the pump cylinder. Two opposite ports 360 are commonly employed to give a total opening of suflicient area. It will be noted that the ports 36b, in the outer lining 53, are positioned above the ports 360 in the pump cylinder lining to permit the separation of gas from the oil in the space 36a, as hereinbefore described in connection with Figs. 20 to 25.

The connection between the exhaust pipe 3 and the exhaust passage 32 may be traced as follows: I

Referring to Fig. 2,- the space w1th 1n upper cap member 50 and the inner operating fluid pipe 3, is connected through a plurality of vertical passages 93 (referring to P 1g. 10) to a passage 94 which connects through a vertical passage 95 in block 61 (the cross sectional shape of which is shown in Fig. 11) to chamber 33 immediately above the check valve 35. A passage 96 extends downward from chamber 33 through the upper pump cyl nder closing member 59 and the pump cyhnder liner 58, the pump piston rod guide 60, the valve chamber lining 63 to port 31 (shown in Fig. 4).

The port 34 connects directly to passage 96 as shown in Fig. 5.

The passage 42, containing check valve 43, may be traced as follows:

The passage 96 extends below port 34 through the motor piston rod guide 64 (referring to Fig. 5), Where it connects with the upper end of check valve 43. The opemng from the lower end of check valve 43 into the upper end of the motor cylinder 7, comprises two passages 97, in the lower piston rod guide section 63. These passages are shown clearly'in Fig. 18.

The passage 25 in the piston rod is formed in the hollow mid-section 10b of the piston rod, the

ports

24 and 26 being shown in Figs. 4 and 5, respectively.

The port 27, having its lower portion 39 of reduced area, is disclosed in Fig. 4. Thus the main portion of the port 27 is substantially oval in shape and of appreciable width, whereas the lower portion 39 is of substantially the same vertical dimension as the portion 27 but is of limited lateral dimension.

From the above description, it is evident that the working model of the actual pump illustrated in Figs. 1 to 19, inclusive, corresponds in so far as its operative features are concerned, exactly with the explanatory diagrams of Figs. 20 to 25, inclusive, the only difference being that Figs. 20 to 25 are drawn disproportionately wide compared to their length in order to simplify the reading of the drawings, and the passages for conducting the fluid to and from the different cylinders and chambers in the pump are shown as pipes outside of the pump proper instead of being formed in the walls'of the pump.

Summarizing, my pump is believed to be particularly effective and eflicient under the conditions encountered in oil well operation because of the following features:

1. The design whereby the main valve moves in response to. operating fluid at a low er pressure than that required to move the p stons whereby movement of the valve is not halted at the time it uncovers a port feeding operating fluid to the motor cylinder;

2. The positioning of the portsmade possible by the aforementioned.featurewhereby the valve supplies fluid through the motor cylinder considerably before the valve reaches the end of its stroke, thus eliminating the cutting off of fluid to the motor cylinder should the valve settle back from its end position; 9

3. The adjacent positioning of the main valve to the piston rod whereby friction therebetween tends to maintain the valve in its proper end position;

4. The interpositioning of exhaust chambers between the high pressure chamber of the valve and the valve faces whereby leakage of fluid from the high pressure chamber to the valve faces is prevented; such leakage might cause false movement of the valve;

5. The design whereby the ports in the piston rod, instead of opening into immovable ports to supply operating fluid to movethe main valve, open into movable chambers in the valve itself, thus permitting admission of pressure fluid to the valve face to move the valve to its desired end position even after the piston rod has commenced its stroke, thus reducing any possibility of the valve being stalled in mid-stroke position by premature movement of the piston;

6. The shaping of the port communicating with the main valve chamber for supplying high pressure fluid to the motor cylinder whereby a small area of the port is initially uncovered, thereby preventing fluid from flowing through the motor cylinder in suflicient volume to reduce its pressure below that necessary to complete the movement of the valve to its desired end position. As has been indicated, this feature is advantageous when abnormal gas conditions exist in the well being pumped;

7. The placing of the pump above the motor, the reverse of the usual practice, whereby the pump piston sucks in well fluid on the up stroke instead of the down stroke, and the upper side of the piston is not continuously exposed to the high static pressure of the column of exhaust fluid in the exhaust pipes extending to the surface.

I claim: 7

1. In a fluid actuated pump comprising a working piston element and a valve piston tion on the sequential movement of said valve piston element, and said working piston element, the method of securing sequential movement of said elements that comprises designing one of said elements to move in response to fluid at a lower pressure than that required to move the other, and supplying fluid simultaneously to both said elements through a common passage at a substantially constant rate of flow, whereby the fluid pressure acting upon both elements at any instant a working piston element and a valve piston the method of operation that comprises adcri element and dependent for its proper opera tion on thesequential movement of said valve piston element and said working piston ele-' ment, the method of securing sequential movement of said elements that comprises supplying fluid simultaneously to both said elements from a common passage at a substantially constant rate of flow, whereby the pressure of said fluid acting upon both said elements at any instant is determined by the reactive force exerted by either of said elements, initially opposing the movement of that element which it is desired to move first with a reactive force less than that applied to the other element, and subsequently at the completion of movement, increasing the reactive force applied to thefirst element above that applied to the other element.

3. In means of the class described comprisin a piston assembly movable into two positlons and having a plurality of faces, a source of operating fluid, an exhaust passage filled with fluid under substantially constant pressure, and a valve movable into two positions and having a pair of opposed faces;

m-itting operating fluid to one face of said valve to move it to its opposed position, subsequently admitting operating fluid through said valve to one of said piston faces when said valve has partially completed its stroke, and preventing movement of said piston before said valve has completed its stroke by impressing said exhaust fluid on faces of said pistonand said valve opposed to said faces exposed to said operating fluid, the ratio of the opposed areas on said motor piston exposed to operating fluid and exhaust fluid respectively being less than the ratio of the opposed areas on said valve exposed to operating fluid and exhaust fluid respectively.

4. In means of the class described, a body member comprising an exhaust passage filled with exhaust fluid under pressure, a source of constant flow of operating fluid, the pressure of said operating fluid being determined by the resistance it encounters, a. pump and motor having pistons connected'together, a piston valve for said motor operable through a stroke between two end positions to admit fluid from said source to said motor piston dunn a substantial portion of each stroke of sai valve, auxiliary valve means to deliver fluid from said source to one end-of said piston valve whereby operating fluid is supplied simultaneously to the piston of sa d motor and to said piston valve during a portion of the stroke of the latter, said valves also operating to expose the opposite surfaces of said piston valve and motor piston to the pressureof said exhaust fluid, and said motor piston and piston valve being characterized in that the ratio of the opposed areas on said motor piston exposed to operating fluid and exhaust fluid respectively is less than the ratio of the opposed areas on said valve exposed to operating fluid and exhaust fluid respectively.

5. In means of the class described, a body member containing an exhaust passage filled with exhaust fluid under pressure, a source of constant flow of operating fluid, a pump comprising a cylinder and piston, a motor comprising a cylinder and a piston therein having a lower acting surface of greater area than its upper acting surface and rigidly connected to the piston of said pump, a piston valve for said motor, said piston valve being operable through a stroke between two end positions to admit fluid from said source to said motor cylinder during a substantial portion of each stroke of said valve, auxiliary valve means to deliver fluid from said source to one end of said piston valve, whereby oper-' ating fluid is supplied simultaneously to the lower face of the piston of said motor and to the lower end of said piston valve during a portion of the stroke of the latter, said valves also operating to expose the upper surface of said piston valve and motor piston to the pressure of said exhaust fluid, and means for applying pressure of exhaust fluid to the upper face of the pump piston during the upward stroke of the latter, the ratio of the combined upper surface of said pump piston and motor piston to the area of the lower surface of the motor piston being substantially greater than theratio of the area of the upper surface of said piston valve to the area of the lower surface of the piston valve.

6. In means of the class described, a body member containing an exhaust passage containing exhaust fluid under pressure, asource of constant flow of operating fluid, a pump and a motor having pistons connected to gether, a piston valve for said motor, said piston valve being operable through astroke between two end positions to admit fluid from said source to said piston during a substantial portion of the stroke of said valve, auxiliary valve means to admit fluid from said source to one end of said piston valve whereby operating fluid is supplied simultaneously to the piston of said motor and to said piston valve during at least a portion of the stroke of the latter, said valves also operating to expose the opposite surfaces of said piston valve and motor piston, respectively, to the pressure of said exhaust fluid, and said motor piston and piston valve being characterized in that the ratio of the areas on said piston valve exposed to operating fluid and to exhaust fluid respectively is greater than the ratio of the areas on said motor piston exstantial portion of the downward stroke of h pressure fluid connected to the bottom of said pump cylinder, a motor comprising a cylinder and a piston therein having a lower act ing surface area substantially greater than its upper acting surface area, means rigidly connecting said motor and pump pistons together whereby they move in the same direction simultaneously, a piston valve for said motor having substantially egual upper and lower surfaces, said piston va ve being operable through a stroke between two end positions to admit fluid from said source to the upper side of said motor piston during a subsaid piston valve, auxiliary valve means to deliver fluid from said source to the upper end of said piston valve wherebyoperating fluid is supplied simultaneously to the upper surface of the motor piston and to the upper surface of said piston valve during a portion at least of the downward stroke of the. latter,

said valvesalso operating to expose the lower surfaces of said piston valve and the lower surface of said pump piston to the pressure of said exhaust fluid whereby the differential pressure between the operating fluid and said exhaust fluid required to move the motor piston downward is greater than that required to move said piston valve downward.

tor cylinder,- a piston in said cylinder, a valve cylinder, a piston valve in said cylinder having chambers therein, a port in said valve cylinder supplying operating fluid to one of said chambers in all positions of said piston valve, an auxiliary valve for supplying fluid from said chamber to move said piston valve, a port opening in said valve cylinder for supplying a limited flow of operating fluid from said chamber to one end of said motor cylinder before said piston valve .hasreached its end position and-another port opening of larger area for supplying a. larger flow of operating fluid to said end of the motor cylinder when said piston valve has reached its end position, whereby the flow of fluid from said chamber to one end of said motor before said piston valve reaches its end said chambers being in constant communication with said exhaust passage and the third chamber being in constant communication with said source .of operating fluid, ports communicating with the upper and lower ends respectively of said cylinder and each registering alternately with one of said first two chambers and said third chamber, in the two positions of said valve, and auxiliary valve means movable with said piston and registering alternately with the opposite ends of said first valve to apply fluid from said source to move said valve during a substantial portion of the stroke of said auxiliary valve.

' 10. In means of the class described, a fluid operated motor comprising a cylinder, a piston in the cylinder, a piston rod, a housing surrounding a portion of the piston rod and concentric therewith, a fluid operated valve member positioned concentrically about said piston rod and sealing with the walls of said ousing, said valve also sealing with said piston rod, a source of operating fluid, an

exhaust passage, a chamber in said valve for,

of its stroke, for admitting pressure fluid to the end of said valve, to move it.

, 11. In means of the character described, a

oto c lind t 'd l" 8. In a device of the type described, a mom r y a pm on m Sm Cy mder a movable in a path parallel to the path of movement of said main valve, and containing a passage registerable with the chamber in said main valve, whereby the admittance of operating fluid to move said main valve is dependent only upon the relative positions of the main valve and auxiliary valve, thus admitting fluid to move said main valve during a substantial portion of the stroke of said auxiliary valve member.

12. In means of the class described, a motor cylinder and a motor piston therein, a source of operating fluid, an exhaust passage, an elongated valve chamber, a valve member movable longitudinally between two end positions in said chamber, a port in the wall of said valve chamber connected to said source of operating fluid, a pocket in said valve mg lac istering with said port in all positions, a second port in said chamber, below said first port, connecting with the upper end of said cylinder and registering with said first pocket in said valve when said valve is in its lower position, a third port in said chamber, above said first port, connecting with the lower end of said cylinder and registering with said first pocket when the valve is in its uppermost position, a fourth port in the wall of said fifth port in the wall of said chamber connecting with said exhaust passage and registering with a third pocket in the valve in all 9 positions, said third pocket in said valve registering with said third port when said valve is in its lowermost position, a piston rodtfor said motor piston having a surface in sliding engagement with said valve, a passage in said piston rod and ports leading from said passage to the contact surface of said piston rod and being so positioned as to deliver pressure fluid from said first pocket in said valve to one end of said valve when the piston is in one end position and to the other end of said valve whenthe piston is in its opposite position, a pair of ports positioned in said piston rod above and below said passage, respectively, one of said ports registering with the lower end of said valve and the second pocket in said valve when said piston is in its lowermost position and the other port registering with the upper end of said valve and said third pocket when the piston is in its uppermost position.

13. In means of the class described, a motor cylinder and a motor piston therein, a source of operating fluid, exhaust passage, a valve movable between two end positions, pressure faces on the ends thereof, and having three chambers therein, two of said chambers being adjacent the respective pressure faces of said valve and being in communication with said exhaust passage and the third chamber being positioned between said first and second chambers and being in constant communication with said source of operating fluid, ports communicating with the upper and lower ends respectively of said cylinder and each registering alternately with one of said first two chambers and said third chamber in the two positions of said valve, an auxiliary valve means movable with said piston and registering alternately with the opposite ends of said first valve to apply fluid from said source to move said valve, the positioning of said first and second chambers in said valve between the third chamber and the pressure faces of the valve preventing leakage from said third chamber to the pressure faces of the valve.

14. In means of the class described, a fluid operated motor comprising a cylinder, a piston in the cylinder, a piston rod, a housing enclosing a portion of the piston rod, a fluid operated valve member positioned in said housing in frictional contact with said piston rod and movable between two end positions in said housing, said valve when in one end position admitting operating fluid to such end of said cylinder as to move said piston and piston rod in such a direction that friction between the piston rod and the valve tends to maintain the valve in its end position throughout the stroke of the piston.

15. In means of the class described, a fluid operated motor comprising a cylinder and a piston in the cylinder, a piston rod, a housing concentrically surrounding said rod and spaced therefrom, a fluid operated valve member positioned in said space concentrically about said piston rod, said valve member when in an end position serving to admit, and exhaust, pressure fluid and exhaust fluid, respectively, to and from such ends of said cylinder as to move said piston in such a direction that friction between the piston rod and the valve member tends to maintain the valve in its end position.

16. In a device of the class described, a piston rod, a pump piston attached to the upper end of said piston rod, said pump piston being provided with a port therein and a check valve in said port for permitting fluid to flow upward therethrough, a pump cylinder in which said pump piston operates, a-passage opening from the lower end of said pump cylinder and extending upwardly to the exterior of the pump, and a passage in the upper end of said pump cylinder containing a check valve for permitting fluid to pass upward therethrough.

17. In means of the class described, a fluid actuated piston motor, a valve for said fluid motor, a passage for conveying operating fluid under pressure to said valve, said valve acting to distribute said pressure fluid alternately to opposite ends of said motor piston whereby the latter is reciprocated, means associated with said piston to admit high pressure fluid alternately to opposite ends of said valve when said piston is in its end positions, a passage leading directly-from said source of operating fluid to one end of said motor piston, and a check valve in said passage for preventing flow of fluid through said passage to the piston but permitting an opposite flow of fluid, an exhaust reservoir, connections between said reservoir and said valve whereby exhaust fluid from said fluid motor may be removed, and a passage connecting said exhaust reservoir to the other end of said piston, and a check valve in said passage for preventing flow of fluid therethrough from said piston but permitting a flow of fluid to said piston.