US2139101A

US2139101A - Hydraulic pumping jack

Info

Publication number: US2139101A
Application number: US101729A
Authority: US
Inventors: Spencer Lloyd
Original assignee: Lane Wells Co
Current assignee: Lane Wells Co
Priority date: 1936-09-21
Filing date: 1936-09-21
Publication date: 1938-12-06
Anticipated expiration: 1955-12-06

Description

DMZ, 6, 1938. 1 SPENCER HYDRAULIC PUMPING JACK Filed Sept. 21, 1936 5 Sheets-Sheet 1 w a r? I HHI I "M v I lira! Dec. 6, 1938. 1.. SPENCER 2,139,101

HYDRAULIC PUMPING JACK Filed Sept. 21, 1936 5 Sheets-Sheet 2 M Wow No /o5 4, .l H 55 5 a a a a 9 z 5 9 m a i I N. figs 9 I l 7. 9 a? 5- e 7 6 7 75 542 w a MW 5 E L M w Y i 5 7 Z 8 I 9 98 a I 3 5 7 8. w

Dec. 611938,

1.. SPENCER HYDRAULIC PUMPING JACK L. SPENCER Dec. 6,1938.

HYDRAULIC PUMPING JACK 1 Fild Sept. 21, 1936 5 Sheets-Sheet 4 f? w 11 1 F q i 5 mllll r25 7K 4 6 I: 5 a w 5, M4 4 1v m- I 1 a M m 1 km; 1 m H I 7 a Iv- 65 'l m 5 1 6 I 5 I Z 55 a M w Dec. 6, 1938. L, SPENCER 2,139,101

HYDRAULIC PUMPING JACK v 1 Filed Sept. 21 1956 5 Sheets-Sheet 5 H Il m 7////////1 w EA I .2

| I 3 a m 1 4 a 5 w, i w 5 I Patented Dec. 6, 1938 UNITED STATES PATENT OFFICZE HYDRAULIC PUMPING JACK Lloyd Spencer, Alhambra, CaliL, assignor to Lane-Wells Company, Los Angeles, Calif., a corporation of Delaware Application September 21, 1936, Serial No. 101,729

20 Claims.

My invention relates to hydraulic pumping jacks, and among the objects of my invention are:

First, to provide a hydraulic pumping jack which is adapted to pump relatively shallow wells capable of being pumped efliciently without or with only partial counterbalancing.

Second, to provide a hydraulic pumping jack which is particularly designed for stripper wells; that is, wells in the last stages of production.

Third, to provide a hydraulic pumphig jack wherein the preponderance of the pumping cycle may be occupied by the working stroke and which incorporates means whereby the duration of the return stroke, and consequently the duration of the entire pumping cycle, may be readily and quickly varied.

Fourth, to provide a hydraulic pumping jack which minimizes the plunge velocity of the well pump during its working stroke and tends to offset any lost efllciency due to the uncounterbalanced weight of the sucker rods.

Fifth, to provide a pumping jack which imparts during both the working and return strokes a substantially constant velocity to the sucker rods.

Sixth, to provide a hydraulic pumping jack which incorporates a special control valve so ar-: ranged as to eliminate any mechanical connec- 30 tion between the valve and moving parts of the pumping jack.

Seventh, to provide a hydraulic pumping jack wherein only the jack cylinder and piston need be located over the well mouth; the remaining ele-' ments thereof comprising a fluid pressure source, control valve, and reservoir arranged in a compact unit located arbitrarily with respect to the jack cylinder and connected therewith by a single pipe line, thereby providing a hydraulic pumping jack which is particularly easy to install and service even on wells having no surface equipment.

mghth, to provide a novel control valve fora hr, draulic pumping jack piston and. cylinder, which valve disconnects the cylinder from a pressure source when the pressure in the cylinder exceeds a predetermined value and reconnects the cylinder with the pressure source when the pressure in said cylinder falls below a predetermined value.

Ninth, to provide a hydraulic pumping jack having cylinder and piston means which incorporate a cushioning device operable at the lower end of its pumping stroke, and a piston retarding means operable at the upper end of the pumping stroke to create pressure conditions in said cylinder below and above apredetermined range in order to affect a control valve associated therewith.

Tenth, to provide a hydraulic pumping jack which, should the pressure within the jack cylinder exceed a predetermined value, automatically reverses movement regardless of the amount of stroke completed; thus providing asafety feature which minimizes the possibility of pulling the sucker rods in two or exerting an excessive strain thereon.

Eleventh, to provide a hydraulic pumping jack which tends automatically to work the well pump free of deleterious matter such as sand or the like without theattendance of an operator; said hydraulic jack limiting its working stroke upon binding of the well pump until such deleterious matter is worked free and then resuming its full working stroke.

Twelfth, to provide a hydraulic pumping jackwhich incorporates a readily accessible, manually operable means for increasing the pressure required to effect reversal in movement on completion of the working stroke, so that when starting the pumping jack after idle periods, or for other reasons, the pumping jack may be caused to exert temporarily an additional pull on the sucker rods; said manually adjustable means in no way aiieqting the normal adjustment of the pumping jack.

With the above and other objects in view as may appear hereinafter, reference is made to the accompanying drawings, in which:

Fig. 1 is a partially elevational, partially sectional view illustrating one form of my pumping jack.

Fig. 2 is an enlarged, fragmentary, sectional view taken through 2-2 of Fig. 1 showing particularly the dashpot arrangement for cushioning downward movement of the jack piston. Fig. 3 is a transverse sectional view through 3-3 of Fig. 2.

Fig. 4 is anenlarged sectional view of the conv trol valve taken substantially through 4-4 of Fig. 1 showing the parts of thevalve in the position assumed when the pumping jack is at rest at the bottom of its stroke or during its working stroke.

Fig. 5 is a similar sectional view showing the parts of the vlave in the position assumed immediately upon reversal prior to the starting of the down or return stroke.

Fig. 6 is a sectional view through 66 of Fig. 1

showing particularly the choke valve for controlling the rate of the return stroke.

Fig. 7 is a sectional view through thecontrol valve at right angles to Figs. 4 and 5 and taken through 1-1 of Fig. 1.

Fig. 8 is a sectional view through lt-ll of Fi 4.

Fig. 9 is a fragmentary sectional view similar to Figs. 4 and 5 illustrating a modified form of pilot valve which incorporates an auxiliary control.

Fig. 10 is an enlarged, fragmentary, sectional view of a modified form of pumping jack and cylinder with the control valve incorporated therein, and including further a hydraulic valve operating device operable independently of the pressure within the jack cylinder.

Fig. 11 is a fragmentary, longitudinal, sectional view through l|--H of Fig. 10 showing particularly the control valve.

Fig. 12 is a transverse sectional view through l2-|2 of Fig. 10.

Fig. 13 illustrates a further modified form of pumping jack cylinder with parts thereof shown in section.

Fig. 14 is a fragmentary elevational view taken at right angles to Fig. 13 and showing the control valve with portions thereof in. section.

Fig. 15 is a transverse sectional view through l5l5 of Fig. 13.

Fig. 16 is a graph illustrating the cycle obtainable with my hydraulic pumping jack.

In the construction shown in Fig. 1, a reciprocator, indicated generally by l, is mounted over the production string 2 of a well and is connected by a single pipe 3 to a control valve 4 which, in turn, is connected to a pump 5 and to a reservoir tank 6.

The production string is provided with a conventional T 1 having a lateral flow line 8 extending therefrom. A conventional polish rod 9 extends upwardly through the T and through the reciprocator l.

The upper end of the T receives a suitable union ll having a special threaded stem l2 adapted to screw into the lower end of a cylinder base l3. At the upper end of the stem l2 there is provided a packing gland follower 14 which is adapted to bear against a packing gland 15 formed within the cylinder base l3. A locknut l6 secures the stem 12 in any adjusted position. Bleeder ports l1 are provided in the follower I4 and base l3 so that any leakage past the gland may be visible.

Above the packing gland l5, the cylinder base i3 is provided with a sleeve bearing I8, and above said bearing the cylinder base is enlarged to form a dashpot cavity I9. Above the dashpot cavity, the cylinder base is further enlarged to receive the lower end of a cylinder 20. Between the cylinder 20 and dashpot cavity 19, the cylinder base is provided with a lateral port 2|.-

The cylinder 20 is provided with a piston 22 having a bore therethrough. for the polish rod 9. The upper end of the piston 22 is threaded to receive a polish rod sleeve 23.

A cylinder head 24 is secured to the upper end of the cylinder 20 and is provided with a sleeve bearing 25 and a packing gland 25 through which extends the polish rod sleeve 23 as well as the polish rod 9. At the protruding upper end of the polish rod sleeve there is provided a packing gland 21, and above the packing gland 21 the polish rod is equipped with a clamp 28. The packing gland 26 need serve only to keep the protruding end of the sleeve free of dirt and thereby protect the bearing 25, for the cylinder head 24 is provided with breather ports 29 which may or may not be protected by filters depending on the location and conditions under which the pumping jack is installed.

A dashpot plunger 3! is secured to the piston 22 and depends therefrom; said plunger comprises a plunger body 32 having a bore 33 therethrough which is substantially larger than the polish rod so as to form a passage. Lugs 34 may be provided to center the lower end of the plunger body with respect to the polish rod. The upper portion of the plunger body is counterbored to receive an annular or cylinder valve 35 having a valve face 36 at its upper end. The plunger body is 'further counterbored and internally threaded, and is provided with a valve body 31 having an annular channel 38 in its lower end flanked by valve seats engageable by the valve face 36 of the cylinder valve 35. Passages 39 communicate between the channel 38 and the upper end of the dashpot plunger 3i. A weak spring Ml tends to hold the cylinder valve 35 against its seat.

The purpose of the valve incorporated in the dashpot plunger is to permit a dashpot action during downward movement of the dashpot plunger in the cavity l9 but admit fluid freely to the dashpot during upward movement of the plunger. The plunger is preferably tapered, or the walls of the cavity may be tapered in order that the dashpot effect may be increased as the plunger moves into cavity.

A stop cylinder 4| fits the sleeve 23 above the piston 22, and is provided at its lowerend with a flange 42 adapted to support a buffer spring 43 which normally extends above the stop and is adapted to engage the cylinder head 24 as the piston reachesthe upper end of its stroke; thus tending to increase the pressure of liquid introduced under the piston. I

Liquid is alternately introduced and withdrawn through the port 2| to efiect reciprocation of the piston; discharge of liquid from under the piston being effected by the weight of the sucker rods.

Movement of the reciprocator is effected by the control valve 4 which may be positioned at any point with respect 'to the reciprocator. The control valve 4 is encased in a housing 5|. housing 5| is provided with a main valve bore which receives a cylindrical liner 52. The bore intersects one,: end of the housing and is here threaded to receive a sleeve 53 which retains the liner 52 in place. Beginning adjacent but beyond its threaded end, the bore intersects first an exhaust port channel 54, an intake port channel 55, a jack cylinder port channel 56, 'and a choke valve channel 51; the several channels being separated one from the other, and the liner being perforated opposite these channels for communication therewith.

The exhaust port channel. 54 merges into a large downwardly directed exhaust port 59 which is adapted to communicate with an exhaust line 59 extending to the reservoir tank 6. The intake port channel 55 intersects a laterally extending intakeport 60 which is connected through a line 6| to the discharge side of the pump 5; the intake side of which is connected through a line 62 to said reservoir tank 5. The jack cylinder channel 56 is connected to a jack cylinder port 62 connected with the line 3. The intake and

jack cylinder ports

60 and 63 are preferably in alignment and extend in opposite directions at right angles to the exhaust port 58.

The choke valve channel 51 merges into a downwardly extending passage 64 which turns The - horizontally past the side of the exhaust port 58 I ing end 1i.

and forms a choke valve port 55. The choke valve port 55 is connected by a Lateral passage 55 with the exhaust port 58. The housing 5! is provided .with an internally threaded bore 51 in horizontal alignment with the choke valve port 65. Y

The choke valve port 55 is preferably conical and is controlled by .a correspondingly shaped choke valve head 58 which is connected by a stem 59 to a threaded traveler 19 mounted in the bore 51 and provided with an outer tool receiv- A locking ring follower I2 also fits the threaded bore 51 to secure the traveler in any adjusted position. The bore 51 is closed by a sealing cap 13 which may be removed for adjusting the choke valve; inasmuch as this valve is in the return line and pressure is nominal, leakage is inconsequential during adjustment operations.

A spool valve 14 is slidably mounted in the liner 52; said spool valve. comprises axially .spaced sealing

flanges

15 and 15. Flange 15 separates the jackcylinder channel 55 from either intake channel 55 or choke channel 51, while sealing flange 15 seals or permits flow between the intake channel 55 and exhaust channel 54. The

two positions of the spool valve are shown bestin Figs. 4 and 5. In Fig. 4, communication is had between the intake port 58 and the jack cylinder port 53; there being no flow through the other ports. In Fig. 5, the flow occurs simultaneously between the intake port 55 and the exhaust port 58, as well as between the jack.

cylinder port 53 through the choke valve port 55 into exhaust port 58. The reason for such flow will be brought out in more detail hereinafter.

The sleeve 53 is provided with a spring 11 which bears against the spool valve 14 and is backed by a traveler 18 so as to urge the spool into the position shown in Fig. 4. The sleeve 53 is threaded for said traveler, and also receives a locking ring 19 so that the traveler may be secured in any'position in order to adjust the tension of the spring 11. A sealing cap 88 covers the outer end of the sleeve 53 except when adjustment is being made. Inasmuch as the interior of the sleeve 53 is exposed only to the nominal pressure in the exhaust line, the leakage during such adjustment is inconsequential.

The end of the spool valve opposite from the spring." is provided with a plunger III which fits into a socket 82 continuing from the main bore of the housing. The end of the housing 5| beyond the socket 52 is provided with a lateral bore' 83 which communicates with the socket 82 through a small passage 84, and also with the choke valve channel 51 through a passage 85; these passages being arranged side by side. The end of the bore 83 towards the'jack cylinder port 53 is in communication therewith through a pas-. sage 85. A liner 81 fits the bore 83 and is provided withexternal channels 88 registering with 1 the

passages

54 and 85. The liner 81 is provided with a bore 89 therethrough which is in communication with the channels 98 by ports 90. Between the ports 90, the bore is provided with a valve seat 9| facing towards the ports communicating with passage 84. The inner end of the liner 81 receives a plug 92 having a passage 93 communicating between the bore 89 and passage 85, and having a valve seat facing said bore 89.

A valve 94 fits the bore 89 and is provided with a head 95 having on one side a conical valve element 95 engageable with the valve plug 92, and

a beveled valve element on the other side engageable with valve seat 9|. The head does not itself seal the bore in which itrides, but permits slight leakage therearound; sealing being dependent upon engagement with either the valve plug 92 or seat 9|.

A stem 91 extends from the valve head .95 through the bore 89, and is guided by a traveler 98. Between the traveler 98 and valve head is 'mounted a stiff spring 99. The bore 89 is threadnient.

Operation of my pumping jack as disclosed in,

Figs. 1 through 8 1s as iollows:

The control valve as shown in Fig. .4 and the reciprocator as shown in Fig. l are at rest ready to start an up or working stroke- Upon operation of the pump 5, liquid under pressure is intherefrom to the jack cylinder port 53 into the cylinder base l3 to lift thepiston 22. The spring 11 holds the spool valve 14 during such flow of liquid for the reason that the pressure areas at 15 are equal, and the pressures against their outer sides are likewise equalbecause the choke valve channel 51 communicates with the exhaust port channel 54 and the head of plunger 8| is exposed through passages 94. and 85 to the exhaust port pressure.

Should the pressure in the jack cylinder port 53, jack cylinder line 3, and cylinder base I3. exceed a predetermined pressure determined by the tension of spring 99, the valve 95 will open and be forced until the valve head engages seat 9|. This does two things. First, communication is established from jack cylinder port 53 through passages 95, 93, and 94 to the head of the plunger Ill. The tension of spring 11 is such that this pressure overcomes the force thereof and urges the spool valve 14 from the position shown in oulder may be provided near .25 troduced through the intake port 55 and passes- .50 the adjacent sides of the sealing flanges 15 and Fig. 4 to that .shown in Fig. 5. As soon as communication is established between jack cylinder port 53 and choke valve channel 51, the pressure in said choke valve channel exerted against the spool valve is suihcient to maintain the valve in the position shown in Fig. 5 during the down stroke.

58 that a pressure difierential exists between the choke valve channel 51 and the exhaust port channel 54 sufficient to overbalance the spring 11.

It should be borne in mind that the piston 22 is urged downwardly by the entire weight of the .sucker rod string which may amount to several hundred pounds. The pilot valve 94 remains open; that is, in the position shown in Fig. 5,

comes supported by the fluid in the dashpot. The

speed of the piston 22 is lowered so that the volume of liquid passing through the jack cylinder port 58 drops until the the opening for which the choke valve port is set can no longer maintain a This is due to the fact that the choke valve port 55 is so restricted by the choke valve pressure difierential between choke valve channel 51 and exhaust channel 54. When this differential drops to the point where it no longer overbalances spring ill, the spool valve is urged to its original position reestablishing communication between the pump 5 and reciprocator.

While liquid is discharging from the pump 5 into the exhaust port 58 during the return stroke of the reciprocator, it should be noted that the capacity of the exhaust port channel 54 and exhaust port itself is sufliciently large to prevent any building up of pressure in opposition to that existing in the choke valve channel 5?.

Normally, the pressure rise in the jack cylinder sufiicient to reverse the control valve occurs when movement of the piston 22 is restrained by the spring 43. However, should the well pump bind or tend. to sand up, orirom any other cause materially increase the load on the polish rod 9, the pressure may rise sufliciently to reverse the valve before the reciprocator completes its working stroke. This operates as a safety feature in at least two ways. First, it is impossible to apply more than a predetermined load on the sucker rods, so that they cannot be pulled in two; and

second, if the trouble is due to sanding up of the well pump, reversal in movement of the well pump when it begins to bind tends to work the sand (which may be only a small amount) through the pump, whereupon, as soon as the pump is free of such obstruction, the jack automatically resumes its full working stroke.

It is intended with devices of this kind that they should operate for long periods of time without attention. However, there are times when it is desirable to exert more than the normal tension on the sucker rods, and at such times an operator is in attendance. For example, after the pump has been idle for a period of time, sand or the like in suspension in the oil may be settled around the well pump so that additional force is required to break it loose. This condition is temporary, and in order to permit this function, a modified pilot valve as shown in Fig. 9 may be substituted for the pilot valve described hereinbefore.

In this construction, the housing SI is substantially the same except that bore 83 may be larger in diameter to accommodate the additional p'arts required. Fitted in this bore is a liner III.

- Similar to the liner 83, the liner III is provided with channels I I2 which register with

passages

84 and 85, and which are provided with ports II3 which communicate with the bore II4 of the liner. Opposite the ports'communicating with the passage 88, the bore I I4 is constricted as indicated by Hi, and inwardly of this constriction forms a check valve chamber H8. The Inner end 01' the liner is threaded to receive a valve plug II'I having a bore II8 therein and a valve seat facing the chamber I I8 which is adapted to be engaged by a ball valve H8. The constriction H5 is also provided with a valve seat facing the .valve chamber II 8 so that the ball valve may engage either valve seat.,

The bore H4 is enlarged outwardly from the constriction I I5, and mounted therein is the head I20 of a valve tappet from which extends a stem I2I fitting the constriction IIB but fluted to insure free communication between the ports II3 therein and the valve chamber H6. The extended end 01 the stem I2I is adapted to bear against the ball valve I I9;

A spring I22 bears against the head I20 of the tappet; being urged thereagainst by a traveler l23 threadedly engaging the outer portion of the bore i M, and adapted to be locked by a follower I23. The spring I22 regulates the tension on the ball valve and, therefore, the pressure required in passage 85 to open the same. As in the first described structure, the ball valve so fits the valve chamber that upon once being opened, is urged outwardly against the seat of the constriction M5 to seal communication between the passages 84 and I355.

The outer end of the liner is covered by a cap I25 having a threaded boss in its outer end which receives an adjusting screw I26. The adjusting screw I26 is secured in a sleeve I 2'! which slidab-ly but non-rotatably receives a pin I 28 having a head I29 in proximity to the head I 20 of the valve tappet. A spring I30 is interposed between the head I29 and the sleeve I21. At the outer end of the sleeve I21, there is provided a sealing washer I3i adapted to seat when the adjusting screw I26 is screwed outwardly as shown in Fig. '9.

Normally, the adjusting screw occupies the outer position shown in Fig. 9 in which position the head I29 clears the head I28 so that the only tension against the check valve is that of spring I22. If, however, it is desired to increase this tension, set screw I26 is turned inwardly until the head I29 bears against head I20 so that both springs I30 and I22 function tohold the check valve H9 seated. The tension of the two springs are so determined that the pressure within the jack cylinder cannot rise to dangerous limits, so that should the operator fail to back off the adjusting screw I26, no damage will occur. As soon as the temporary condition requiring the extra pressure in the jack cylinder has been alleviated, the adjusting screw I26 is returned to its normal position. It should be noted that operation of the adjusting screw in no manner interferes with the adjustment of spring I22.

In both of the pilot valves illustrated, it should be borne in mind that a slight clearance is provided around the check valve, so that should the seat between the check valve and valve plug 92 or III leak slightly, no pressure is built up in the passage 84 but is bled out passage 85.

Reference is now directed to Figs. 10, 11, and 12 in which is illustrated a modified form of my pumping jack. In this construction, the control valveis incorporated integrally with the reciprocator. This is accomplished by adding an integral collar I4I to-the side of housing BIA intersected by the Jack cylinder port 63, so that said port now discharges directly into the collar I4I (housing SIA being identical to the housing 5| except for the changes herein noted). The cylinder base I3 in this arrangement screws into the bottom of the collar I, while the cylinder 20 screws into the top thereof. In place of socket 82, passages 84, B5, and 86, as well as the bore 83, there is substituted in the housing 5IA a constricted bore I42 continuing coaxially with the main bore having the liner 52 therein.

The bore I42 is provided with a sleeve I43 enlarged at its upper end and threaded to receive a bellows shell I44. The shell I44 is cylindrical and supports by'its upper end 9. depending bellows I45 preferably of the sylphon" type. Attached to the free lower end of the bellows I46 is a bar H6. The bar I46 is adapted to engage the spool valve 14 which, in this construction, is

without the plunger 8|.

The sleeve I48 is provided near its inner end port 58. The bar. I46 and sleeve I43, of course,

fit as snugly as possible so that leakage through the passage I49 is nominal. 1

Substituted for the cylinder head 24 is a modified cylinder head I 50, into the lower end of which is screwed the cylinder 20. The cylinder head I is in most respects similar to the head 24 except that above the cylinder 28 thereis mounted a ring I5I held in place by set screws I52 extending through the side walls of the cylinder head. Depending from the ring I5I is an annular bellows I53 having an outer corrugated wall I54 and an inner corrugated wall I b oth sealed to the ring I5I and connected together at their lower extremities by an annulus I56. The annulus I56 is adapted to be engaged by a buffer spring I51 carried by the piston 22 in the manner of the spring 43; said bufier spring I51, however, being lighter in construction.

The ring I5I is provided with an annular channel I58 therein which is intersected by a laterally extending pipe I59. The pipe I59l is adapted to extend outwardly through a boss I68 provided in the head I50, which boss is equipped with a packing gland I6I. The pipe I59 is connected by a tube I62 to the bellows I45. The interiors of the bellows I45 and I53 are filled with liquid so that collapsing of bellows I53 expands bellows I45.

In addition to the packing bland I 6|, the boss I68 may be provided with a laterally directed port I63 which may serve as a breather port and to which may be attached suitable air strainer means, not shown. Operation of this form of my pumping jack is as follows:

The spring 11 normally holds the valve 14 in its upper position; in which case, introduction of pressure tends to raise the piston 22 and continues to raise the piston until the spring I51 engages the bellows I53 forcing the liquid therein outwardly through pipe I59 and tube I62 so as to extend the bellows I45 and urge the bar I46 downwardly against the spool valve 14. As soon as the spool valve has been urged to its lower position, the pressure under the piston 22 is available, as in the first described structure, to maintain the spool valve in its lower position.

Attention is now directed to Figs. 13, 14, and 15. In this construction also, the control valve is in most respects identical to that of the first de-; scribed structure and is designated 5IB. The valve housing 5IB is joined to a collar I4I similar to the valve 5IA but preferably with the exhaust port 58 directed upwardly. The exhaust port 58 is connected through a 1' HI to a return line I12 and a riser pipe I13. The riser pipe I13 communicates with a cylinder head I14 so that liquid may be introduced on top of the piston 22. The piston 22 is provided with an upwardly extending dashpot cylinder I15 which is adapted to receive a dashpot plunger I16 depending from the head I14 and loosely. surrounding the sleeve 23.

In the present arrangement of the control valve, the plunger III of the spool valve and its socket 82' are retained, but in place of the pilot valve structure there is substituted a lateral port I11 which is connected by a tube I18 to a port I19 in the cylinder head I14, which port communicates withthe annular space between the dashpot'plunger I16 and sleeve 23. Operation of this form of my pumping jack is as follows:

The cylinder 20 both aboi and below the piston 22 is filled with liquid. During the upstroke, the liquid above the piston discharges out the riser I13 and into the line I12. Inasmuch as this is the only fluid flowing in the return line, there is practically no back pressure on the piston. When, however, the plunger I16 receives the dashpot cylinder I15, pressure in the line I18 is raised,

building the pressure up in the socket 82 sufll-' ciently to overpower the spring 11 and permit the down stroke of. the piston 22. During such down stroke, both the fluid from the pressure source and that discharging from under the piston is delivered to the exhaust port 58. Part of this flows into the top of the cylinder 28 while the remainder returns to the storage tank. Although air may get into the system, liquid amply suflicient to flll theidashpot cylinder I15 is discharged from the riser I13 above the piston 22, thereby insuring proper action of this dashpot.

It is preferred to operate my pumping jack in such a manner as to have a comparatively long and slow up stroke and a comparatively rapid down stroke, as shown in Fig. 16. By adjusting the choke valve 68, it is possible to vary the length of the down stroke, as indicated by the dotted lines in Fig. 16. By adjusting the tension of spring 11, the dashpot action at the lower end of the stroke may be readily varied. For example, the less tension exerted by spring 11, the lower must be the pressure in line 3 in order to permit upward movement of the spool valve. This means that the dashpot plunger 3| must enter deeper into the dashpot I9 and olIer greater retarding effect tomovement of the piston. On the other hand, the greater the tension of spring 11, the less pressure drop required in line 3, thereby requiring a lesser dashpot action. I

With reference to the first described structure, there is no pressure surge at the beginning of the up stroke, and this is due to the fact that the entire effective area of the piston 22 is available during the initial up stroke by reason of the check valve arrangement incorporated in the dashpot plunger 3|. Further, even in relatively shallow wells there are several inches of stretch in the sucker rods; consequently, the piston moves an appreciable distance before the 'entire weight of the sucker rods and well liquid is carried thereby. Therefore, unless the well pump should bind from deleterious matter, no'pressure surge occurs until the piston reaches the up end of its stroke.

By reason-of the fact that the polish rod 9 extends entirely through the reciprocator, it is readily adjustable up or down withoutrcmoving the reciprocator. If, however, it is desired to move this apparatus, only the polish rod clamp 28, the line 3, and the union I I need be disconnected. Upon this being done, the apparatus may be lifted vertically from the polish rod. Also, to adjust the packing gland I5, it is merely necwsary to loosen the union II and locknut I6, then rotate thefollower I2.

Though I have shown and described particular embodiments of my invention, I do not wish to be limited thereto, but .desire to include in the scope of my invention the constructions, combinations, and arrangements embraced in the appended claims.

I claim:

1. In a hydraulic pumping jack: a hydraulic reciprocator having a return stroke under urge of an unbalanced load, and a working stroke in opposition thereto; a fluid supply means; a valve having a primary position connecting said fluid supply means with said reciprocator for ingress of fluid thereto, and a secondary position for permitting discharge of fluid from said reciprocator; a device operatively associated with said reciprocator for shifting'said valve from its primary to its secondary position; means operatively associated with said valve in its secondary position for maintaining a back pressure in said reciprocator during its return stroke; and an instrumentality responsive to a back pressure drop below a predetermined value for urging said valve to its primary position.

.2. In a hydraulic pumping jack: a hydraulic reciprocator having a return stroke under urge of an unbalanced load, and a working stroke in opposition thereto; a fluid supply means; a valve having a primary position connecting said fluid supply means with said reciprocator for ingress of fluid thereto, and a secondary position for permitting discharge of fluid from said reciprocator; a pressure responsive device operatively associated with said reciprocator for shifting said valve from its primary to its secondary position; a discharge regulator for said reciprocator operatively associated with said valve in its secondary position to determine the duration of return stroke, said regulator tending to maintain a back pressure in said regulator and against said valve to hold the same in its secondary position; and an instrumentality responsive to a back pressure drop below a predetermined value for urging said valve to its primary position.

3. In a hydraulic pumping jack: a hydraulic reciprocator having a return stroke under urgeof an unbalanced load, and a working stroke in opposition thereto; a fluid supply means; a valve having a primary position connecting said fluid supply means with said reciprocator for ingress of fluid thereto, and a secondary position for permitting discharge of fluid from said reciprocator; a device responsive to pressures in said reciprocator above a predetermined value for shifting said valve from its primary to its secondary position; and an instrumentality responsive to a pressure drop in said reciprocator below a predetermined value for shifting said valve from its secondary to its primary position.

4. In a hydraulic pumping-jack: a hydraulic reciprocator having a return stroke under urge of an unbalanced load, and a working stroke in opposition thereto; a fluid supply means; a valve having a primary position connecting said fluid supply means with said reciprocator for ingress of fluid thereto, and a secondary position for permitting discharge of fluid from said reciprocator; a pressure responsive device potentially operative during the entire working stroke of said reciprocator to shift said control valve from its primary to its secondary position and reverse movement of said reciprocator should the pressure therein exceed a predetermined value, whereby said reciprocator automatically terminates its working stroke; and an instrumentality responsive to a pressure drop in said reciprocator below a predetermined value for shifting said valve from its secondary to its primary position.

5. The combination with a wellpump and a sucker rod string extending to the well mouth, of a hydraulic pumping jack comprising: a reciprocator including a cylinder adapted to be mounted over a well mouth, a piston. therein, and a polish rod attached to said sucker rod string and adjustably connectible to said piston, said piston having a return stroke under urge of said sucker rod string, and a working stroke in opposition thereto; a fluid supply means; a valve having a primary position for connecting said supply means with said chamber and a secondary position permitting discharge of fluid from said chamber; a device operatively associated with said reciprocator for shifting said valve from its primary to its secondary position to cause a return stroke of said piston; means operatively associated with said valve in its secondary position for maintaining a back pressure in said chamber during the return stroke of its piston, said valve'having a pressure area exposed to such back pressure tending to maintain said valve in its secondary position; and an instrumentality responsiveto drop in said back pressure below a predetermined value for urging said valve to its primary position.

6. The combination with a well pump and a sucker rod string extending to the well mouth, of a hydraulic pumping jack comprising: a reciprocator including a cylinder adapted to be mounted over a well mouth, a piston therein, and a polish rod attached to said sucker rod string and adjustably connectible to said piston, said piston having a return stroke under urge of said sucker rod string, and a working stroke in opposition thereto; a fluid supply means; a valve having a primary position for connecting said supply means with said chamber and a secondary position permitting discharge of fluid from said chamber; a device responsive to pressures in said chamber above a predetermined value for shifting said valve from its primary to its secondary position; and an instrumentality responsive to a pressure drop in said chamber below a predetermined value for shifting said valve from its secondary to its primary position..

'7. The combination with a well pump and a sucker rod string extending to the well mouth, of a hydraulic pumping jack comprising: a reciprocator including a cylinder adapted to be mounted over a well mouth, a piston therein, and a polish rod attached to said sucker rod string and adjustably connectible to said piston, said piston having a return stroke under urge of said sucker rod string, and a working stroke in opposition thereto; a fluid supply means; a valve having a primary position for connecting said supply means. with said chamber and a secondary position permitting discharge of fluid from said chamber; a pressure responsive device potentially operative during the working stroke of said piston to shift said control valve from its primary to its secondary position thereby to reverse movement of said piston should the sucker rod load exceed a predetermined value; and an instrumentality potentially responsive during the entire return stroke of said piston to shift said valve from its secondary to its primary position upon drop of pressure in said chamber below a predetermined value, thereby to cause a working stroke of said piston.

8. In a hydraulic pumping jack: a hydraulic reciprocator having a fluid discharging return stroke under urge of an unbalanced load, and a fluid intaking working stroke in opposition thereto; a control valve having a primary position connecting said reciprocator with a fluid supply, and a secondary position for permitting discharge of fluid from said reciprocator; yieldable means urging said valve from its secondary to its primary position; a device operatively associated with said reciprocator for shifting said control valve in Opposition to said yieldable means to tersaid reciprocator applicable on said valve for,

holding said valve in its secondary position; and a cushion means operative at the end of the return stroke of said reciprocator to diminish discharge of fluid therefrom and render said regulator ineffective whereby said yieldable means returns said valve to its primary position.

9. In a hydraulic pumping jack: a hydraulic reciprocator having a fluid discharging return stroke under urge of an unbalanced load, and a fluid intaking working stroke in opposition thereto, said reciprocator including a pressure augmenting means operative at the end of its working stroke in conjunction with said load to create a peak pressure in said reciprocator, and a cushion means operative at the end of the return stroke of said reciprocator to create a pressure drop therein; a fluid supply; a discharge line; a back pressure regulator in said'discharge line; a control valve having a primary position connecting said fluid supply with said regulator, and a secondary position connecting said reciprocator through said regulator with said discharge line; a device responsive to said pressure peak for shifting said valve to. its secondary position; and an instrumentality responsive to said pressure drop for shifting said valve to its primary position.

10. In a hydraulic jack: a hydraulic reciprocator having a common fluid supply and discharge line, and incorporating means tending -to create a pressure peak insaid-line when said reciprocator reaches one end of its stroke, and a means tending to create a pressure drop in said line as said reciprocator reaches the other end of its stroke; a fluid supply; a discharge line; a back pressure regulator in said, discharge line;

a control valve having a primary position con- 7 necting said fluid supply with said regulator, and

a secondary position connecting said reciprocator through said'regulator with said discharge line; a device responsive to said pressure peak for shifting said valve to its secondary position; and an instrumentality responsive to said pressure drop for shifting said valve to its primary position. 11. In a hydraulic jack: a hydraulic reciprocator having a common fluid supply and discharge line, and incorporating meanstending to create a pressure peak in said line when 'said reciprocator reaches one end of its stroke, and

means tending to create a pressure drop in said .line as said reciprocator reaches the other end v of its stroke; a fluid reservoir; a pump having an intake from said reservoir; and a control valve structure interposed between said pump and reciprocator and having a discharge port to said reservoir, said valve structure including amain valve having a primaryposition connecting said pump with said reciprocator line and a second position connecting both said reciprocator line and pump with said discharge port, yieldable means urging said main valve from its secondary to its primary position, a pilot valve responsive to a pressure peak in said reciprocator line for urging said main valve to its secondary position in opposition to said yieldable means, a meter valve interposed between said port and main valve tending to maintain a back pressure in said reciprocator line applicable to hold said main valve in its secondary position, and means for rendering said meter valve ineffective to permit operation of said yieldable means.

12. In a hydraulic pumping jack: a hydraulic reciprocatorhaving a return stroke under urge of an unbalanced load, and a working stroke in Obiosition thereto; a fluid supply means; a valve a. primary position connecting said fluid supply means with said reciprocator for ingress of fluid thereto, and a secondary position for permitting discharge of fluid from said reciprocator; a, pressure responsive device potentially operative during the entire working stroke of said reciprocator to shift said control valve from its primary to its secondary position and reverse movement of said reciprocator should the pressure therein exceed a predetermined value, whereby said reciprocator automatically terminates its working stroke; a main regulating element for said device to determine the normal pressure at which said device responds; and an auxiliary regulating element for said device determining an augmented pressure at which said device responds.

13. The combination with a fluid motor, a pressure fluid supply means, and a reservoir, of a control valve comprising: a main \valve having a primary position connecting said supply means and motor; and a secondary position connecting both said supply mea ns and motor with said reservoir; yieldable means constantly urging said main valve to its primary position; a pilot valve responsive to pressures, in said motor above a predetermined value for urging said main valve to its secondary position; a meter valve interposed between said main valve and reservoir tending to maintain a back pressure in said motor operable to retain said main valve in its secondary position, said yieldable means adapted upon drop in said back pressure below a predetermined value to return said main valve 'toits primary position.

14. A control valve comprising: a valve body having a press e fluid intake port, a surge port, and an exhaus port; a main valve'incorporated .in said valve body and having a primary position connecting said intake port with said surge port, and a secondary prisition connecting both said surge and intakeports with said discharge port; I

'a pilot valve responsive to pressure in said surge port above a predetermined value to admit fluid against said main valve urgingthe same .to its .secondary position; a meter valve interposed be tween said main valve and discharge port tending to maintain aback pressure in said surge port main valve being held by said back pressure in its secondary position; and yieldable means conduring flow therefrom to said discharge port, said position connecting said reciprocator with'said reservoir; means continuously urging said valve into its primary position; a device periodically operable in opposition to said means for urging said valve into its secondary position; and a back pressure regulator for controlling discharge from said reciprocator, said valve including a pressure area exposed to said back pressure when said valve is in its secondary position, thereby maintaining said valve in such position in opposition to said means, whereby upon falling oil of the back pressure, said valve tends to return to its primary position.

16. In a hydraulic pumping jack: a hydraulic reciprocator having a return stroke under urge of an unbalanced load and a working stroke in opposition thereto; a valve structure for controlling ingress and egress of fluid to and from said reciprocator, said valve comprising a mu]- tiple-ported valve body defining fluid paths communicating with said reciprocator; a valve element in said valve body moveable between a primary and a secondary position to control said fluid paths; means continuously urging 'said valve element into its primary position; a device periodically operable to urge said valve element into its secondary position; and a regulator for one of the fluid paths established when the valve element is in its secondary position tending to maintain a back pressure therein while the fluid velocity therethrough exceeds a predetermined value, said valve element incorporating a pressure area responsive to said back pressure in op-' position to said means, whereby when the velocity falls below said predetermined value said means returns the valve element to its primary position.

1'7. A valve structure comprising: a multipleported valve body; a valve element therein moveable between a primary and secondary position to control fluid paths through said valve body; means continuously urging said valve element into its primary position; a device periodically operable to urge said valve element into its secondary position; a regulator for one of the fluid paths established when the valve element is in its secondary position, said regulator tending to maintain a back pressure therein while the fluid velocity therethrough exceeds a predetermined value.

18. A control valve comprising: a valve body having a pressure fluid intake port, a surge port and an exhaust port; a main valve incorporated in said valve body and having a primary position connecting said intake port with said surge port, and a secondary position connecting both; said surge and intake ports with said discharge port;

means continuously urging said valve element into its primary position; a device periodically operable to urge said valve element into its secondary position; and a regulator for the fluid path from said surge port to said exhaust port tending to maintain a back/pressure at said surge port when the velocity therethrough exceeds a predetermined value, said valve element incorporating a pressure area responsive to said back pressure in opposition to said means, whereby when the fluid velocity through said surge port falls below said predetermined value, said means returns the valve element to its primary position.

19. In a hydraulic pumping jack: 9. reciprocator including a piston and cylinder means defining a working chamber and an idler chamber, said piston having a return stroke under urge of an unbalanced load and a working stroke in opposition thereto; a pressure liquid supply means; a reservoir; a control valve in communication with both of said working and idler chambers, said supply means, and said reservoir, the control valve having a primary position connecting said supply means with said reservoir and a secondary position connecting both of said chambers and said supply means with said reservoir whereby said idler chamber tends to maintain a charge of liquid therein; means tending to cause a pressure rise in said idler chamber when the piston approaches the end of its working stroke; means for transmitting such pressure to said control valve to shift the same from its primary to its secondary position; and an instrumentality operable at the end of the return stroke of said piston to return said control valve to its primary position.

20. In a hydraulic pumping jack: 9. reciprocator including a piston and cylinder means, the piston having a return stroke under urge oi. an unbalanced load and a working stroke in opposition thereto; a pressure fluid supply means; a control valve having a primary position connecting said supply means with said reciprocator to urge the piston through a working stroke, and a secondary position permitting discharge of fluid from said reciprocator during the return stroke of said piston; an auxiliary pressure fluid system including a pressure-exerting element operatively associated with said piston at the end of its working stroke, a pressure transmitting line, and a pressure responsive device associated with rsaid control valve adapted when actuated to shift control valve from its primary to its secondary position; and an instrumentality operable at the end of the return stroke of said piston to return said control to its primary position.

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