US2902884A - Multiple cylinder, elastic fluid counterbalanced pump jack - Google Patents

Description

Sept. 8, 1959 L. A. BLACKBURN MULTIPLE CYLINDER, ELASTIC FLUID COUNTERBALANCED PUMP JACK Filed June 22, 1956 2 Sheets-Sheet l 5. 9 a w MM2 ,F 5 ONMWM \||I\MN1\ nl l.. h o 2....... E U v|| a ll 2 a- .n .y ,um 6

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J5 895 Je 22 2a 22 JNVENTOR. EaZ/67 d. @Zcza 77a Sept- 8, 1959 l.. A. BLACKBURN 2,902,8 184 MULTIPLE CYLINDER, ELASTIC FLUID COUNTERBALANCED PUMP JACK 2 Sheets-Sheet 2 Filed June 22, 1956 MULTHLE CYLINDER, ELASTIC FLUID -COUNTERBALANCE-D PUMP lACK Luther A. Biaekbum, Los Angeles, Calif. Application .ame 22, 11956, serialNo. 593,151

s claims. l(ci. 'M -589) p This invent-ion relates to pressure balanced, walking beam type, oil well pumping jacks, and more specifically contemplates havingan air head exerting pressure against a lubricating foam which in turn exerts a .counter-balancing pressure on a group of pistons for reciprocation of a sucker rod string within a well; the rod vstring and uid pumped being partially counterbalanced to substantially equalize the weight lifted by the power unit on opposite strokesof the well pump. The load upon the jack changeswith each stroke, as on the vdown stroke of the sucker rod string, the we-ight of the rods chiey constitutes the load, while on -the up stroke, the weight ofthe column of iluid is raised also with the rod string. The present application is an improvement .and is a `continuation-in-part of my co-pending application S. N. 394,405, led November 25, 1953, now Patent No. 2,756,602 for lubricating foam balance Adeep oil well pumping unit.

The structure consisting essentially of .a walking beam having one end thereof pivotally supported by a Samson post and having a horsehead mounted on its opposite end having means for connection with a polish rod in a well pumping unit, and said beam being recipro'cated by a power means having connections with a gear ,reducer and a yoke intermediate the beams ends. Further, a counterbalancing pressure tank is pivoted to its forward end between the yoke and the horsehead, and contains a group of four cylinders and pistons mounted Within its lower end', which project into an inner tank having its lower end in open communication with the first mentioned tank which, in turn, is sealed from the atmosphere by the cylinder and piston mount. The pistons" rod ends are mounted upon a rocker base plate having Va' center rib resting in a grooved self-aligning swivel plate situated upon the forward cross memberbeam, `which rocker plate rocks in unison with the vertical swinging motion of the horsehead. An air head pressure is maintained within the upper part of the rst mentioned tank, exerting pressure upon a sub lubricating foam pressure covering the cylinders and piston heads in its lower part, the foam pressure on the piston heads serving to counterbalance the total weight of polish rod with its sucker rod string plus one-half the fluid weight within a tubing string in a well.

A principal object of this invention is to provide counter balance means which creates a cushioning effect upon the sucker rods during its reciprocating movements with resultant reduction of the breakage of sucker rods compared with the conventional type pumping jacks having United States Patent 2,902,884 Patented Sept. 8, 1959 revolving counterbalance weights, and also providing less -stress upon the ent-ire pumping jack during pumping operation. ,Y

Another object is to provide a ,pressure `counter balance mechanism comprising a group of small cylinders Aand ypistons adapted to minimize the large conventional size cylinder bore and .piston now in use and minimizing friction and leakage between the pistons and cylinder walls.

Another object is the ,provision of a pressure tankmain- Vtaining an air pressure in its .upper part and a grease pressure in its lower part having communication and maintaining an equal pressure in unison with a counterbalance tank, by means of a pipe line kconnecting the upper ends of both tanks, the `pipe line extending from :the upper part of the pressure tank, and up through the center of -the counterbalance tank into its upper .air ,Ahead chamber, and also a pipe line extending from the lower port of the pressure tank and up through the piston Vrods to a groove in the center of each piston, conveying rand maintaining a grease seal -under pressure between the cylinder walls and pistons, the pressure in each tank and piston groove being equal, provides a minimum possibility of foam pressure leakage past the piston from the counterbalance tank.

Another object is to provide a iluid tank containing a lubricating foam forming fluid, and having pipe connections between the pressure tank and the counterbalance tank, the pressure tank supplying pressure to the uid tank by means of an air compressor having pipe connections with the pressure tank. A shut oi valve .is closed in the main pipe line between the pressure tank and the counterbalance tank, and with the valves open vin a secondary pipe line between the iluid tank and-the counterbalance tank, and by the actuation of the vair compressor lubricating foam forming Huid is conveyed to the piston chamber in the counterbalance tank, where the foam forming fluid is transformed into a lubricating foam pressure by the reciprocating action of the counterbalance tank and the cylinders on the pistons, thereby lubricating the cylinder walls and acting as an additional seal around the upper part of the pistons, while providing a counterbalancing pressure between the air head .and the pistons within the counterbalance tank.

Another object is to provide an air compressor to maintain an equal pressure between the pressure tank, the counterbalance tank, and the center Vpiston grooves; the pressure being equal between the air head in the upper part of the counterbalance tank, and the lubricating foam in its lower piston chamber with an equal pressure between the lubricating foam on` the piston heads and the grease seal in the center piston grooves, all pressures being equal in the mechanism.

Another object is to provide a manual shut ott valve in each pipe line, a shut off valve in the pipe line connecting the air compressor and the upper end of the pressure tank, 'the pressure tank having air pressure in its upper part and a grease pressure component consisting of graphite grease invits lower port, and a shut ofr valve in the pipeline extending from the upper port of the pressure tank to the air head chamber in the upper inside center part of the counterbalance tank, the above valvesl remaining open during pumping operaton; `also a shut off valve in the pipe line extending from the upper part of the compression tank to the upper part of the fluid tank, and a shut oif valve in the pipe line extending from the lower part of the uid tank to the piston head chamber Within the lower part of the counterbalance tank.

Another object is to provide a rocking base plate for the piston rods to rest upon, each piston rod having a center pin extending from its lower end and into properly spaced loose fitting holes in a swivel base plate, allowing clearance for each rod and piston to align itself within the cylinder walls; the base plate having a V- shaped rib on its under side and resting in a loose iitting 'V-shaped groove in a swivel plate having a pin in its under side center and projecting downward through a hole in the center of an H beam cross member in the lower front part of the framework, providing self-alignment, and freedom of action between the walking beam and the pistons as they reciprocate with the vertical swingying motion of the horsehead, and the swaying motion of the counterbalance tank and cylinders.

Another object is to incorporate an air pressure regulator on the air compressor and a safety relief valve on theV pressure tank so as to maintain a correlative predetermined yair head and lubricating foam pressure upon the piston heads within the counterbalance tank. Y Still another object is to provide a frame for the support of the mechanism having large I beams spaced parallel to one another on each under side of the pumping jack mechanism, having two cross member I beams welded together and projecting cross-wise through square open spaces cut in the sides of the front and center sections of the large parallel I beams, so as to provide a means to secure the pumping jack to a concrete foundation by bolting it down to embedded bolts projecting from the concrete and up through each end of the small I beams.

Y Other objects, advantages and salient features of my invention, such as for example, the provision of lubricating foam counterbalance pistons having holes bored from the center groove to each triple ring groove, conveying an equal grease pressure behind an endless double flanged rubber band which is seated behind each set of triple rings in each piston ring groove, thereby maintaining under pressure a rm seating of the piston rings against the cylinderwalls, the grease pressure being conveyed from the pressure tank which contains a graphite grease in the lower part thereof, and conveying the grease pressurethrough the lower end of the pistons to each ring groove, further minimizing foam pressure leakage between the pistons and cylinder walls, which comprises an integral part of the pump jack, as well as simplicity of construction, relative economy of manufacture, assembly and operation, to meet specific requirements, will be apparent from the following description read in the light of the accompanying drawings, in which:

Fig. l is a` perspective view of the entire air-head foam balance Vpumping jack embodying the invention assembled as in use, showing the piston rods resting upon the rocking base plate and the position of the air compressor and the air-grease pressure tank, as well as the small I beams protruding from the sides of the parallel H beam frame, With bolts securing the jack to the foundation,

Fig. la is a reduced scale top plan view of the base constructionof the pump jack,

Fig. 2 is a sectional view in elevation, with cut away sections of both tanks depicting the principal air headfoam V'balance mechanism, which is enclosed within a cylinder `shaped counterbalance tank; portions being broken away to show the inner tank, and the group cylinder section with the pistons having circumferential grooves around their center sections for the purpose of providing a grease seal between the pistons and cylinder walls. Also three pipe lines are shown, as follows: The

pressure line that carries the `grease seal with its outlets terminating in each piston groove, and the air head line that maintains the air head pressure with its outlet terminating above the inner tank and foam level, and the line that carries the foam fluid with its outlet terminating above one of the pistons. The forward end of the framework of the framework is also shown, showing the position of the piston supporting rods resting upon a rocking base plate having a rocker rib on its under side which rests Within an enlarged groove in a self-aligning swivel plate. j

Fig. 3 is a cross-sectional view of the air head lubricating foam counterbalance tank taken on the line 3 3 of Fig. 2, showing the `air head pipe line cylinder in the center, surrounded by the main cylinder group arrangement within the inner and outer tank components,

Fig. 4 is a detailed sectional and fragmental elevational view taken on the line 4-4 of Fig. 3 showing the construction of the cylinders and pistons as well as the support of the pistons by their piston rod cornponents. The gure also shows the -use of a grease seal in a circumferential groove in each piston as well as the grease pressure biasing of the piston ring combinations comprising an outer metal ring backed by a flanged rubber band,

Fig. 5 is a sectional view taken generally on the line 5 5 of Fig. 3 showing the lower end of the counterbalance tank assembly and the support therefor on the rocker base plate and certain portions being broken away for clearness of illustration,

Fig. 6 is a perspective top plan view of the rocker base plate which supports the pistons and piston rods; one end being broken away to show the rib seating. Also shown are the holes for the piston rod pins, and a center hole which provides a seating position for the air pipe line rod, and

Fig. 7 is a perspective view of the air compressor having pipe connections with a compression tank containing air in its upper part and grease in its lower part, resting upon the parallel I beam frame, and a foam fluid tank resting in a horizontal position between the I beams. A cut-away section is shown in each tank showing the grease level in the pressure tank, and the foam uid level in the foam iiuid tank. A pipe line is shown extending from the compressor to the pressure tank having a shut off valve, and a pipe line extending from the pressure tank to the fluid tank having a shut-off valve, and tgwo other sectional pipes, with shut off valves, one extending from the upper air chamber section of the pressure tank to the air-head chamber of the counterbalance tank in Fig. 3 and 4, and the other pipe extending from the grease chamber in the lower part of the pressure tank to the piston grooves as shown in Fig. 3 and 4.

Referring to the drawings, the numerals of which indicate similar parts throughout the several views, =15 designates generally the foundation of the pumping jack, comprising two I beams spaced parallel to one another, having short I beam curved sections 16 welded to each outer side of the said parallel I beams 15 frame work for the support of each Samson post section 17, with brace supports 17a welded between the forward end of the said I beam 15 frame, and the said Samson posts 17. Further, a short I beam section 18 with one end curved and welded to the rear side of one of the I beams 15 serves as an additional support for the engine 19.

In order to secure the said I beam 15 framework to its concrete foundation 15a, double H beams Ztl are provided, welded together in pairs to form a ilanged box section and which protrude transversely through the said I beams 15 through square holes 21 cut in their sides with the said H beams 20 protruding from both sides of the said I beam 15 framework and which are secured by bolts 22 to the said foundation.

Further, spacer H beams 23 are welded at proper intervals between the said parallel I beams 15 for the rigidity of the framework together with a spacer beam 23u between one ofthe beams 15 andthe end of the beam 18.

A cylinder shaped counterbalance tank 30 having four cylinders 31 engaging pistons 28 mounted in said cylinders is interposed between a walking beam 31a and the front H beam 23 and has its upper end pivoted by a bearing 90 to the said walking beam 31a. The pistons 28 are icarried by the upper ends of piston rods 29 the lower ends of which are mounted upon a rocker base plate 24, which has a transverse rocker rib 25 on its under side resting in its groove 25a in a cradle base 26 and which base has a center pin 27 projecting from its under side through a hole 27ain the top center of the transverse H beam 23 and which loosely secured therein by a nut 27b giving the said base 26 capacity to swivel for proper self-alignment of the rods 29 and pistons 28 in the cylinders 31 when the air foam counterbalance tank 30 with its cylinders 31 reciprocate.

Each piston rod 29 is provided with an anchoring pin 32 Fig. 5, which projects from the center of its lower end into one each of the equi-spaced holes 33 in the base 24, Fig. 6, holding the said piston rods 29 in place thereon. Each hole 33 is slightly larger than the pins 32 so as to permit the pistons 28 to center themselves in the cylinders 31. Preferably the cylinders 31 are welded in equi-spaced holes cut in a round steel plate 34, the plate 34 being bolted around the edges to a circumferential flange 35 in the lower end of the counterbalance tank 30. The inner flange 35 rests upon a gasket 36 between it and plate 34 which electively seals the counterbalance bottom Hange` 35 to the icylinder base plate 34.

A small bore cylinder 38 is also welded in a hole 37 cut in the center of plate 34 and carries an inner tank 40 mounted upon its upper end and secured on a ange 39 therein by a nut 41. The function of the said cylinder 38 is to permit and direct the passage of air runder pressure from the air compressor 63 and compression tank 42 to the air head chamber 43 within the counterbalance tank 30. The air is conveyed from the upper part of the pressure tank 42 by means of a pipe line 44 which has a manual shut off valve at a point in the said line with the pipe 44 extending to the lower end of a hollow rod 46 slidingly engaging the cylinder 38 and conveying air pressure through the rod 46 and cylinder 38 to the air head chamber 43.

The lower end of the said rod 46 is anchored to the center of the rocker plate 24 by means of a pin 48 projecting from its lower end, and through the center hole 49 of the said plate and a set of piston rings 47 on its upper end engages the interior of the cylinder 38 while packing box screwed to the lower end of its cylinder 3S serves to complete the sealing pressure within the chamber 43, while the Icounterbalance tank 30 with its cylinders 31 and 38 are reciprocated in union by the action of the walking beam. The power means includes the engine 19 ywhich drives the gear reducer 89 secured to the frame by bolts 89a; said reducer having crank arms 91 driving pitman rods 92 connected to an equalizer yoke 93 pivoted by a bearing 94 to the walking beam 31a and thus reciprocating a sucker rod string in a well 61a through a polish `rod 61 connected to the horsehead hanger 32 by means of a cable sling 62 and a clamp 62m.

A counterbalancing air pressure 43 in the upper part of the said tank 30 is maintained upon a lubricating foam 52 in the lower part of the vsaid counterbalance tank 3l) and in the cylinders 31 and on the piston heads 28 and in the inner tank 40, with both the air and foam being in open communication with one another through the lower open end of the said inner tank 40', thereby maintaining a lubricating `counterbalancing foam contacting the piston heads 28. The foam 52 may, for example, be like that disclosed in my said prior application and may be supplied to the inner tank from air pressure conveyed 'from the upper part of the pressure tank 42 through a pipe 53 having a manual shut-ofi valve 54 and connected to the upper part of a fluid tank 55 containing a foam forming fluid 56. The fluid tank being subjected to air pressure conveys the uid 56 through a pipe line 57 having a manual shut ofr valve 58 and the pipe 57 extending to and up through one of the cylinders 31 and through the side of one of the pistons 28 With its outlet above the piston head 59. A drain ycock valve 6i) is also provided in the said pipe line 57 in order to occasionally test the consistency of the said foam during pumping operation when valve 58 is closed. However, normally valves 54 and 58 remain open with valve 45 closed when conveying the said fluid to the lower part of the counter balance tank 30; drain cock valve 58a in pipe line 44 being provided to partially release the air pressure from compartment 43 in tank 30 to the atmosphere so that the foam forming fluid may flow freely under the pressure of the pressure tank 42 forcing the foam forming fluid from the fluid tank 55 to the inner tank 48, whereby with the initial air in tank 30, the reciprocation of the cylinders 31 and inner tank 40 over the pistons 28 transforms the foam forming fluid into a lubricating foam by the agitation thereof. Then with valves 54, 58 and 58a closed, and with valves 45 and 65 remaining open, actuation of the air compressor 63 maintained a predetermined air pressure in tank 30 upon the lubricating foam suicient to counterbalance the Weight of the polish rod 61 with its sucker rod string and one-half the fluid weight in a well.

It will be observed that the air head pressure 43 in the upper part of tank 38 and the foam pressure 52 in the lower part Iof tank 30 is built up simultaneously against one another in uniformity of pressure. The air is conveyed to the upper part of tank 30 from pressure tank 42 through pipe line 44, and as the foam forming fluid is forced into the lower p-art of tank 30 through pipe line 57, a jet of compressed air is released into the said pipe line 57 through a partially open valve 97 in pipe 96 mixing with the said uid and causing the said fluid to be transformed into foam as it jets into the lower part of tank 30. Y

The lubricating foam forming fluid may be the s-ame formula as my said co-pending application for lubricating foam balance deep oil well pumping unit, using a soap detergent with a mixture of ammonia, oil and water as follows:

Percent Powdered soap detergent 10 Distilled water 50 Ammonia 3 Refined petroleum oil 37 A satisfactory soap detergent composition may be formed from the following formula:

Percent Soap powder 921/2 Ammonium carbonate 11/2 Sodium carbonate l Saponin 2 Soap bark 3 A quantity of the soap detergent and ammonia combined with the water and oil transforms completely into a lubricating foam element sufficient to fill the lower part of tank 30 to level 72. Without limiting myself to any particular composition of the liquid, the above formula is illustrative of a composition which proves effective for the purpose described.

The air pressure is created and maintained by the act-nation of an air compressor 63 which through a regulator 66 maintains predetermined pressure range in the pressure tank 42 and consequently also in the counterbalance tank '30 by means of a pipe line 64 connection` between the said compressor 63 and, the said pressure tank 42 and a pipe line 44 connection between the said pressure tank 42 and the counterbalance tank 30 with their respective valve 65 and 45 remaining open during pumping operation.

For safety measures the pressure tank 42 is equipped with a relief valve 68 and a pressure gauge 69, designed to Work in unison with the air pressure regulator 66 so that proper adjustment can be maintained in the said regulator during pumping operation. i

A graphite grease 70 is provided in the lower part of the pressure tank 42 which is supplied from time to time through plug 71 lling the tank 42 to level 72, and is subjected under air pressure equal to the pressure in lEhe counterbalance tank 30, and is conveyed through a pipe line 73 and its open valve 74 to a hollow steel block 75, havingy a T connection 76 at each end of the said block connecting all four piston rods 29 at a point designated 77 conveying the said grease under constant pressure up through a bore 78 in each piston rod 29 and through a hole 79 in each piston 28 to a center circumferential groove 80 in each piston 28, the pressure on the grease in the grooves being equal to the pressure in the counterbalance tank 30 and in the pressure tank 42 acts as an added seal between the pistons 28 and cylinder walls 31 to prevent the foam from leaking past the pistons.

In order to further insure the seal between the pistons and the cylinder walls, a hole 81 is bored from each center piston groove 80 to each piston ring groove 82. The grooves 82 each have a group of three piston rings with a double flanged rubber circumferential seal situated behind each set of triple rings with the rubber flanges resting inwardly in a groove cut within the ring groove 82, grease under the imposed pressure and conveyed from tank 42 is imposed upon the back side of the circumferential rubber seal 83 thus causing the piston rings to exert a constant pressure against the cylinder walls.

Without limiting myself to any particular composition of the graphite grease seal the following formula is illustrative of a composition which proves effective for the purpose described.

Percent Powdered graphite High pressure petroleum grease 95 The operation of the pumping jack is initiated by starting of the engine 19, with the V belts 84 temporarily disengaged from the engine pulley 85 and with the V belt 86 temporarily disengaged from the compressor pulley 87, the compressor 63 is actuated by a temporary V belt extending from the engine pulley 85 to the compressor pulley 87 as shown by dotted lines 88 and with the pump jack gear reducer 89 being disengaged from the engine 19 only during the initial pumping up of the entire pressure system, and with the proper amount of foam forming fluid having been injected into the lower part of the counterbalance tanks 30 and 40, and with V belts 84 and 86 replaced and with V belt 88 disconnected, and as the entire mechanism is put into operation, the fluid is raised in foam volume to its proper level 51 by its transformation to foam upon agitation by reciprocation of the unit. The predetermined air pressure is imposed upon the lubricating foam which in turn is imposed upon the pistons to an extent equal to the weighttof the sucker rod string and one-half the lluid weight in the tubing string is attained. It will be understood that in the cycle of each stroke it is not possible to counterbalance the total amount of the iluid weight in the tubing string, since on alternating strokes the iluid weight is transferred from the pump barrel plunger to the tubing string at its lower end. Sufficient power, therefore, must be delivered by the engine 19 to raise the unbalanced load on its upstroke, and to overcome the counterbalancing pressure on its down stroke. t

" The single embodiment of my invention shown in the drawings hereof and described above, is only illustrative of numerous modications which may vary from the specic form depicted in number, shape, size, design and proportion of the -various parts, and that any changes that `fall -within the denitions of the claims appended hereto are included within the scope of the appended claims.

I claim:

l. In an oil well pumping jack actuating a sucker rod in a well tubing string, the combination of a frame, a Samson post and a walking beam having one end pivoted to the said Samson post and having a horsehead hanger hinged to its opposite end; said walking beam carrying an equalizer yoke pivoted to said walking beam intermediate its ends and having said ends connected with the crank arms of a gear reducer and a power means, a pressure counter balance tank having its upper end pivoted to the lforward end of said beam between said yoke and horsehead with its lower end having a group of cylinders mounted therein reciprocating in unison on a like group `of pistons with each `stroke of the pumping jack; said tank having a counterbalancing air head in its upper part with a corresponding lubricating foam in its lower part working in conjunction with one another to counterbalance a load in a Well and constituting the primary counterbalancing medium for the pump jack.

2. In an oil well pumping jack actuating a sucker rod in a well tubing string, the combination of a frame, a Samson post, and a walking beam having one end pivoted to the said Samson post and having a horsehead hanger at its opposite end; said walking beam carrying an equalizer yoke pivoted'intermediate its ends and said ends connected with the crank arms of a gear reducer and a power means, a pressure counterbalance tank having its upper end pivoted to the forward end of the said beam between the said yoke and horsehead and having a group of cylinders mounted therein; said cylinders reciprocating on pistons supported by rods having their ends anchored upon a rocker base having a rocking motion on said frame keeping the said rods and pistons in alignment within said cylinders during each vertical stroke of the said beam and swaying motion therewith of the said tank, an air head in the upper part of the said tank exerting a counterbalancing pressure upwardly against the said beam and downwardly against a lubricating foam in its lower part exerting pressure upon the said pistons thrusting the said tank and beam upwardly counterbalancing a load in a well, an air compressor maintaining a predetermined pressure in the said tank by means of a regulator in connection with the said air compressor,

' eective to counterbalance the weight of the sucker rods plus one-half the weight of the fluid in an oil well being pumped by said jack.

3. An air sub-foam counterbalanced oil well pumping jack for actuating a sucker rod in a well tubing stringy comprising the combination of a frame, a Samson post, and a walking beam having one end pivoted to the said Samson post having a horsehead hanger hinged to its opposite end; said walking beam carrying an equalizer yoke pivoted intermediate its ends and said ends being connected to the crank arms of a gear reducer and a power means driving said gear reducer, `an air `and foam containing counterbalance tank subjected to pressure having its upper end pivoted to the forward end of the said walking beam in a vertical position between said yoke and horsehead and having a group of cylinders, pistons mounted in said cylinders and supported by piston rods; with the lower ends of said piston rods being mounted upon a rockable base, said base having a rib disposed ina groove in a cradle and having capacity for swivel movement for alignment; the said air counterbalance tank having connections with a compression tank, the compression tank having direct connections with an air compressor controlled by a pressure regulator to maintain a predetermined air pressure in the upper part of 'the 'said Icompression tank av quantity of grease inthe lower part of said compression tank, a pipe line having a manual shut off valve and a drain cock -valve at a point in the said line and extending ,from the upper part of the said compression .tank to the upper center of the said counterbalance tank and maintaining an equal air head pressure in both tanks, a second pipe line having a manual shut off valve -at a point in the said 'line and extending yfrom the lower part of the said compression tank conveying .grease 4under pressure to a center circumferential groove in each of the said pistons forming a seal between the said cylinders and pistons to prevent foam from leaking past the said pistons, a third pipe line having a shut off valve at a point in the said line extending from the said compression tank to a foam iiuid containing tank having a pipe line with a shut olf valve and a drain cock valve at a point in the line extending up through the side of one of the said pistons conveying a quanti-ty of a lubricating foam forming iluid up through the side of one of the said pistons effective to supply the lower part of the said counterbalance tank with a lubricating foam sucient to cover the said cylinders and pistons in response to actuation of the said air compressor; the reciprocating action of the said counterbalance tank and cylinders on the said pistons and the air head in the upper part of the said counterbalance tank exerting suicient pressure against the said foam and pistons to counterbalance the polish and sucker rod string weight plus one-half the weight of the fluid in a Well on the up stroke of said string.

4. An air and foam counterbalanced oil Well pumping jack comprising a walking beam with one end pivoted to a Samson post and a horsehead hanger at its opposite end; said walking beam carrying an equalizer yoke intermediate its ends and said ends having connections with the crank arms of a gear reducer and a power means for actuating the sucker rod stri-ng in a well, an air and foam pressure counterbalance tank pivoted to the forward end of the said beam and having a group of cylinders mounted in the said tank reciprocating on a group of pistons with each stroke of the said walking beam, said pistons -being carried by piston rods and said piston rods at their lower ends being mounted upon a rocker base, said tank having .a lubricating foam level above said pistons in the lower part of the said tank with an air pressure head in the upper part of the said tank, and means to maintain a predetermined pressure comprising an air compression tank, an .air compressor, and a regulator to actuate said air compressor whenever the pressure within the said air foam tank falls below a predetermined level.

5. In an air and lfoam pressure counterbalanced oil well pumping jack, a Walking beam having its rear end pivoted to a Samson post, and means at its forward end affording connection to a sucker rod string, and an equalizer yoke carried by the said walking beam .and connected by pitman the arms of a gear reducer, a power means driving said reducer, an air and foam pressure counterbalance tank pivoted in an upright position near said Iforward end of said walking beam and carrying a group of cylinders engaging a group of pistons mounted within the said tank and sealing the air and foam therein, and an inner tank with its lower end open within the said balance tank and coniining the lubricating foam to the piston area.

6. In an air `foam counterbalanced oil well pumping jack, a frame, a walking beam pivoted at one end to a Samson post and having a horsehead means at its opposite end affording connection with a sucker rod string, driving means comprising an equalizer yoke pivoted intermediate its ends to walking beams and having connections with the arms of a gear reducer, a power means driving said reducer; the movement of said walking beam reciprocating an air and foam containing counterbalance tank connected to said walking beam, a group of cylinders carried by said tank, a group of pistons engaging said cylinders,

a group of piston rods supporting said pistons mounted and anchored upon a rocking base carried by said frame, said counterbalance pressure tank being pivoted to the forward end of the said beam, said tank having an inner tank mounted therein with its lower end open, said counter balance tank having a counterbalancing air pressure in its upper part exerting pressure on a lubricating foam in its lower part, said foam being confined to the lower part of the said counterbalance tank and to the said cylinders and piston .area within the said inner tank and 'in open communication with the said air pressure, and an air compressor with a regulator having connections Ywith a compression tank, with the upper part of the said tank containing air pressure and the lower part of the said tank containing grease, said tank having a pipe line conveying the said grease to a circumferential groove in each of said pistons sealing the foam within the said air foam counterbalance tank from leaking past said pistons, and a pipe line conveying air pressure simultaneously from said compression tank to the upper part of said air and foam containing counterbalance pressure tank, said pressures being equal within both said pressure tank and counterbalance tank, and the said grease pressure within the said piston grooves being equal to the said tank pressures, said air compressor being actuated by the said regulator to maintain the said pressures above a predetermined minimum level sufiicient to counterbalance the weight of the polish rod and sucker rod string and onehalff the duid weight in a well tubing string on the up stroke of the pump.

7. An air and foam counterbalanced oil well pumping jack comprising a walking beam with one end pivoted to a Samson post and means to connect .a sucker rod string to its opposite end, an equalizer yoke pivoted thereto intermediate its ends and having driving connections with an actuating gear reducer, a power means driving said reducer; said beam having a reciprocating counterbalance tank pivoted to its forward end, said tank having an air pressure confined to its upper part and a lubricating foam. coniined to its llower part, said tank having an inner tank mounted over and enclosing a group of cylinders and pistons and confining the said lubricating foam to the piston heads, said lubricating foam being in open communication with said air head and said air head pressure imposing a pressure by said foam upon the heads of said pistons sulicient to counterbalance the load of the rod string in a well, an air compressor and a pressure regulator having connection with a compression tank having air pressure in its upper part and grease in its lower part, a pipe line extending from the said compression tank to the said counter balance pressure tank, said pipe extending up into a cylinder arrangement in the center of the said group of cylinders, thereby conveying air pressure to the said conned air head in the upper part of the said counterbalance tank, and a second pipe line conveying grease under pressure from the said compression tank to circumferential grooves in each of the said pistons effective to seal the pressure within the said counterbalance tank; all said pressures being maintained equal in the said tanks and piston grooves.

8. In a oil well pumping jack for actuating a sucker rod string in a well tubing string, the combination of a frame, a Samson post, a walking beam having one end pivoted to the said Samson post, means for connecting a Sucker rod string to its opposite end, a yoke pivoted to said walking beam intermediate its ends having said ends connected to a gear reducer, a power means driving said reducer, a cylinder shaped counterbalance tank pivoted to said forward end of said walking beam and having a group of cylinders mounted therein, a piston in each of said cylinder; said pistons being supported by piston rods resting upon a rocker and cradle base carried by said frame, and a counterbalancing pressure means in said tank comprising air pressure exerting pressure upon a lubricating foam contacting the said piston vheads sucient to counterbalance the load Yof the rod string in a well, a compression tank carried by said frame comprising a connterbalancing air pressure in its upper part and a'grease component in its lower part, the said compression tank simultaneously conveying su'cient air under pressure to the upper part of the said counterbalance tank and grease under equal pressure to circumferential grooves in the said pistons and simultaneously behind a set of triple piston rings carried by each piston, each of said rings comprising a double anged circumferential rubber `seal against the back side of each 0f the said piston rings, causing the rings to expand and exert con- 412 tinuous ring pressure against said cylinder walls equal to the said air and foam pressure within the said counterbalance tank.

References Cited in the le of this patent UNITED STATES PATENTS 2,162,125

Saxe June 13, 1939 2,293,915 Patterson Aug. 25, 1942 2,514,310 Busse et al. July 4, 1950 `2,664,764 Blackburn Jan. 5, 1954 2,745,660 Delahay May 15, 1956 2,758,969

Perri et al. Aug. 14, 1956

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