US3222940A

US3222940A - Counterbalance means

Info

Publication number: US3222940A
Application number: US151723A
Authority: US
Inventors: Chastain Joe
Original assignee: Individual
Current assignee: Individual
Priority date: 1961-11-13
Filing date: 1961-11-13
Publication date: 1965-12-14
Anticipated expiration: 1982-12-14

Description

Dec. 14, 1965 J. CHASTAIN 3,222,940

COUNTERBALANCE MEANS Filed Nov. 13, 1961 2 Sheets-Sheet I LOAD L851 INVENTOR Joe Chustoin ATTORNEYS Dec. 14, 1965 J. CHASTAIN COUNTERBALANCE MEANS 2 Sheets-Sheet 2 Filed NOV. 13, 1961 Fig.6

INVENTOR Fig.9

Fig. 8 4 Joe Chostom Mi I BY W W ATTORNEYS United States Patent ()fiFice 3,222,940 Patented Dec. 14, 1965 3,222,940 COUNTERBALANCE MEANS Joe Chastain, PO. Box 4035, Midland, Tex. Filed Nov. 13, 1961, Ser. No. 151,723 7 Claims. (CI. 74-41) This invention relates to counterbalance means for balancing unequal loads which are moved in alternate reciprocal movements and, more particularly, to counterbalance means for reducing the peak torques on the drive shaft of a power unit which is adapted to move the unequal reciprocating loads.

One object of this invention is to provide a new and improved counterbalance means for unequal reciprocating loads which are moved in reciprocation whereby the peaking of torque on the drive shaft of the power unit moving such loads is reduced.

Another object of the invention is to provide a new and improved counterbalance means adapted for application to reciprocating movement pumps and to provide load equalizing means whereby the variations in the load on the motor driving the pump are minimized during each cycle of operation of the pump.

Still another object is to provide a new and improved pump, of the reciprocating movement type, having a counterbalance means which automatically varies in accordance with the reciprocating movement of the pull or lift rods of the pump to minimize the variations in the load on the motor during each cycle of operation of the pump.

A further object is to provide a reciprocating movement type pump including a pump jack and a mechanical linkage for translating the rotary motion of a drive shaft to oscillating movement of the pump jack lever wherein the driving means directly connected to the pump jack lever for oscillating the same forms one side of a parallelogram linkage which maintains the angle between the driving means and pump jack lever at approximately ninety degrees and wherein the line of force applied to one end of the pump jack lever by said driving means is parallel to the line of force applied by the opposite end of said pump jack lever to the pull or lift rods of the pump throughout the upstroke and downstroke movements of the pump jack lever, thereby effecting an efficient transfer of energy between the drive shaft and pump lift rods.

A still further object is to provide a new and improved counterbalance means adapted for application to reciprocating movement pumps wherein the effective force of a counterbalance mass or weight is varied during each cycle of operation of the pump to provide for a uniform distribution of torque on the drive shaft of the motor driving the pump.

A still further object is to provide a new and improved counterbalance means adapted for application to reciprocating movement pumps which varies automatically in accordance with the reciprocating movement of the pull or lift rods of the pump to minimize variations in the load on the motor driving the pump and to provide for a uniform distribution of torque on the motor drive shaft during a cycle of operation of the pump without any pronounced peaking.

Additional objects and advantages of the invention will be readily apparent from the reading of the following description of a device constructed in accordance with the invention, and reference to the accompanying drawings thereof, wherein:

FIGURE 1 is a schematic fragmentary side view of a pump mechanism including a pump jack and counterbalance means therefor and showing the parts thereof in the positions they assume during the downstroke of the pump;

FIGURE 2 is a schematic fragmentary side view of the mechanism of FIGURE 1 showing the parts thereof in the positions they assume during the upstroke of the pump;

FIGURE 3 is a fragmentary end view of the pump mechanism of FIGURE 1;

FIGURE 4 is a graphic comparison of the load capacitor with a constant input torque of a unit with the counterbalance means of this invention and a unit with a conventional counterbalance means;

FIGURE 5 is a schematic fragmentary side view of a pump mechanism including a pump jack and having a modified form of counterbalance means therefor and showing the parts thereof in the positions they assume during the downstroke of the pump;

FIGURE 6 is a schematic fragmentary side view of the mechanism of FIGURE 5 showing the parts thereof in the positions they assume during the upstroke of the P p;

FIGURE 7 is a fragmentary end view of the pump mechanism of FIGURE 5;

FIGURE 8 is a graphic illustration of the torque imposed on the pump motor drive shaft by a conventional counterbalance means;

FIGURE 9 is a graphic illustration of the torque imposed on the pump motor drive shaft by the counterbalance means illustrated in FIGURES 5, 6 and 7;

FIGURE 10 is a fragmentary side elevation of a modification of the mechanism of FIGURE 1; and

FIGURE 11 is a fragmentry side elevation of a modified form of crank arm and counterweight which may be used with either pump jack mechanism. 2

Referring now particularly to FIGURES l to 3 of the drawings, a reciprocating movement pump jack mechanism 10 is shown mounted on a flat base or support 11. The pump, itself, may be of a type suitable for pumping wells, such as oil wells, whereby a piston (not shown) may be attached in the usual manner to the pull or lift rods 13 of the pump and slidably mounted in a well flow conductor or casing which communicates with a pool or reservoir of liquid to be pumped. The piston may be provided with a conventional by-pass valve or gasket which will permit flow of liquid in the conductor past the piston during the downward stroke of the lift rods and piston and which will prevent flow of liquid past the piston during the upstroke of the lift rods and piston, thereby causing the liquid to be lifted out of the reservoir during the upstrokes of the lift rods and piston.

The lift rods are attached to an arcuate support or horsehead 14 at the end of the pump jack lever or walking beam 15 from which they are suspended substantially vertically. A bracket. 17 attached to the underside of the pump jack lever intermediate its ends is provided with a sleeve, saddle bearing or the like, for connection with a horizontally disposed pivot bar or shaft 18 mounted in the upper ends of a support frame 19. The support frame may include a substantially vertical Samson post 20 and an angular brace 20a. The pivot bar 18 thus provides a fulcrum for the reciprocating oscillatory movements of the pump jack lever.

The end of the pump jack lever remote from the lift rods has a bracket 21 attached to its underside providing a tail-bearing connection with a horizontal pivot pin 21a which is connected at its ends to a pair of pitman rods 22 by means of suitable bearing couplings 23. The pitman rods extend downwardly parallel to each other and are pivotally connected at their lower ends to a drive crank or arms 24 by means of pitman bearing couplings 25. Each of the couplings 25 receives a horizontally disposed crank pin or pivot 27 carried by its associated drive crank or arm at a point intermediate its ends. The drive cranks are mounted parallel to one another on opposite ends of a transmission driven shaft 28 of a speed reducer 29. The shaft 28 is driven by a drive shaft 30 of the speed reducer, being connected to the drive shaft by a drive chain 32, or other suitable means, such as a gear train, which operatively connects a driven sprocket 33 on the transmission driven shaft with a drive sprocket 34 on the drive shaft. The drive shaft 30 is journalled in a. pair of upright bearing supports 35 and 36 on the base 11. The gears and chain of the speed reducer 29 are enclosed within a housing or gear box case 37 having at its lower end a hollow bearing sleeve (not shown) which is journalled on the drive shaft 30 so that the speed reducer housing may pivot about the drive shaft. The drive shaft 30 has a pulley 39 rigidly secured thereon so that the drive shaft may be rotated by a suitable belt (not shown) driven by a motor (not shown), in the usual manner.

A pair of auxiliary beams or levers 40 are each attached at one end to a coupling 40a rotatably disposed on the crank pins Or pivots 27. At its other end each auxiliary beam is pivotally connected to the Samson post 20 by a pivot pin 41 mounted in a bearing bracket 42 secured to the Samson post preferably substantially vertically below the pivot bar 18 for the pump jack lever. As shown in FIGURES 1 and 2, the auxiliary beams 44) are disposed parallel with the walking beam or pump jack lever 15. The pitman rods 22, which are parallel to one another, are also disposed substantially parallel to the plane between the fulcrum pivot 18 and the pivots 41 on the Samson post 20 and to. the pump lift rods 13, thus describing a parallelogram linkage or framework wherein the auxiliary beams 40 constitute one side of the parallelogram and together with the pump jack lever 15 comprise a first pair of opposite sides, while the pitman rods 22 which are connected to the pump jack and auxiliary beams also form one side of the linkage and are maintained substantially parallel to the plane through the

pivots

18 and 41 at the other side of the linkage. It will also particularly be seen that the pitman rods 22 are at all times maintained substantially parallel to the pump lift rods 13 by virtue of their connection with the pump jack lever 15 and the auxiliary beams 40 of the parallelogram linkage which swing from the stationary support 19 to maintain the pitman rods in a vertical position parallel to such lift rods during the swinging reciprocating movement of the pump jack lever. The lift rods 13 move in a vertical line because of their flexible connection with the horsehead 14. g

It will thus be apparent that the cranks 24, which are driven simultaneously in a rotary movement about the transmission shaft 28 of the speed reducer, cause the pitman rods 22 and the end of the pump jack lever 15 which the pitman rods are secured to move downwardly relative to the shaft 28 as the cranks are moved downwardly in a counter-clockwise direction as shown in FIGURE 2. Further, it will be seen that the pitman rods and the end of the pump jack lever to which they are secured move upwardly relative to the shaft 28 as the cranks move upwardly in a counter-clockwise direction as shown in FIGURE 1. However, because of the provision of the auxiliary beams 40 which hold the lower ends of the pitman rods, the gear box is forced to oscillate in a limited arc of pivotal movement about the shaft 30 as the cranks are rotated by the shaft 28. The speed reducer gear box is pivoted to the right, as shown in FIGURE 2, when the cranks move downwardly; and to the left, as shown in FIGURE 1, when the cranks move upwardly. The ar-cuate distance of pivotal movement of the speed reducer gear box is preferably substantially equal to the vertical stroke of the pumping unit lift rods.

Like the pump jack lever 15, the auxiliary beams 40 which hold the lower ends of the pitmans are also subjected to a limited pivotal movement about their respective pivots 41 by the rotation of the cranks. Thus, the pitmans are moved laterally toward and away from the Samson posts 20 during each cycle of rotation of the cranks, the amount of such lateral movement being very small, since the arcs described by the pivoted ends of the pump jack lever and the auxiliary beams are small as compared to the length of the lever arms forced thereby. Consequently, the pitman rods 22 remain substantially vertical at all times and the force applied thereto is substantially longitudinal thereof at all times, and is parallel to the force applied on the horsehead end of the crank jack by the load acting on the pump lift rods.

It will be apparent that the torque on the drive shaft or power shaft caused by the weight of the lift rods and piston, and the column of fluid supported on the piston, will change during each cycle of operation of the pump. The peak torque load during the upstroke of the rods will have a large positive value because of the weight of the lift rods and the fluid supported on the piston, whereas during the downstroke the weight of the lift rods and such fluid as remains on the piston will act to produce a negative torque on the shaft. Thus, it Wlll be noted that the greater the weight of the column of fluid lifted, the greater will be the peak torque on the driving shaft during the downstroke and upstroke in each cycle of operation of the pump, and the greater will be the loads imposed on the speed reducer and the motor.

To reduce these torque peaks, a counterbalance weight W is mounted on each crank arm 24 at the end thereof which is remote from the driven shaft 28 of the speed reducer, the mass of the weights and the distances from the driven shaft 28 when the same are secured to the crank arms determining the effective force exerted by such weights. It will be noted that during the upstroke or lifting movement of the pump 10, as illustrated in FIGURE 2, the crank 24 and counterweights W apply or exert a downward force on the pitman rods and therefore on the end of the walking beam of the pump jack which is remote from the lift rods. Thus, during the upstroke movement of the lift rods, the counterweights W assist the power shaft of the prime mover in lifting the lift rods 13 and the column of fluid above the piston. During the downstroke movement of the elements, as illustrated in FIGURE 1, it will be noted that the counterweights W exert their force in opposition to the swinging movement of the crank arm and resist upward movement of the pitman rods and the end of the pump jack remote from the lift rods. It will also be noted that when the counterbalance weights W are positioned as shown in FIGURE 2, during the upstroke of the pump jack, the counterweights act in conjunction with the force applied to the pitman rods by the crank arm and thus produce a larger downward force acting on the pitman rods and on the pitman rod end of the pump jack lever to provide for the application of a greater lifting force to the lift rods 13. This arrangement therefore produces a greater effective downward force applied to the pitman end of the pump jack lever during the lifting or upstroke of the pump lift rods and a lesser or smaller effective force on the pitman rod end of the pump lift rods, whereby the force applied to the pitman rod end of the pump jack lever by the gear reducer, crank arms and counterweights varies in accordance with the load applied to the horsehead end of the pump jack lever during the up and down strokes of the lift rods. It is believed obvious that the rotation of the crank arm may be in either direction, though it has been described as counter-clockwise, and that rotation in either direction would produce the same effective force applied to the pitman rod end of the pump jack lever. The mass of the gear box always imposes a slight torque acting downwardly on the pitman rods except when it is in vertical alignment with such rods.

It is also to be noted that the pitmans 22 remain or are held in a position substantially parallel to the lift rods 13 throughout the rotary movement of the cranks and the pivotal movements of the pump jack lever and the auxiliary beams. Thus, the angle between the pitmans and the pump jack lever changes but slightly throughout the up and down strokes of the pump, and never varies greatly from ninety degrees. Consequently the force exerted on the pump jack lever approaches the eificiency obtainable with an ideal infinite length pitman. Of course, the counterbalance weights do not impose any torque on the pitman rods 22 when the crank arm 24 is in vertical alignment with the pitmans 22.

It will also be seen that the torque or force applied to or imposed on the pivots 27 at the lower end of the pitman rods and the outer end of the auxiliary beams by the gear reducer and counterweights during each cycle of operation of the pump will always be opposite to the torque on such pivots resulting from the weight of the lift rods and piston and the column of fluid supported on the pump piston. The graphic illustration in FIGURE 4 provides a comparison of the loads which can be lifted by a conventional pumping unit with the loads which can be lifted by a pumping unit having the parallelogram auxiliary beam construction of this invention. In each case a constant torque is applied from the gear reducer 23 and a given counterbalance W is mounted on the crank arm. Curve A illustrates the maximum load capacity which can be lifted on the upstroke by the unit of this invention having the parallelogram auxiliary beam construction, and curve B illustrates the minimum load capacities which can be lifted on the downstroke of the same structure. The maximum load capacity which can be lifted by a conventional unit is illustrated in curve C showing the maximum load capacity for the upstroke of the unit. Curve D shows minimum load capacity for the downstroke. If loads are greater on the upstroke or less on the downstroke than the values indicated in the curves, then torque over load would result, with a torque applied to the gear reducer in excess of the capacity of the gear reducer. It will particularly be noted that the load capacity available applied during the major portion of the movement of the crank arm and of the pump jack unit of this invention is substantially level and gives space for a rectangular substantially horizontal dynamometer card without overloading the pumping unit for the parallelogram structure of this invention, as compared with the necessarily angularly disposed dynamometer card required for the standard counterbalance structure.

Referring now particularly to FIGURES 5 through 9 of the drawings, which illustrate a preferred form of the pump jack mechanism, the pump jack 110 comprises an upright support 111 which is mounted at one end of a. base 112. The support includes a pair of substantially A-shaped side frames 111a and 11112. An elongate walking beam or pump jack lever 113 is pivotally supported intermediate its ends on the top of the support 111 by a saddle bearing connection or bracket 114 afiixed to the lower surface of the pump jack lever which receives the horizontal pivot pin 115 mounted on and extending between the side frames 111a and 11111. One end of the beam is provided with a horsehead 116 to which pump pull or lift rods 117 are attached and depend therefrom. The lift rods are adapted to be attached to a load (not shown) whereby the load may be moved reciprocally upon oscillatory movement of the pump jack lever 113. For instance, a piston may be attached to the lift rods and moved within a well flow conductor or well casing for lifting fluid from an underground reservoir. The piston may be provided with a valve of conventional type which permits passage of fluid past the piston during a downstroke thereof but prevents passage of fluid past the piston during the upstroke thereby thus causing the lifting or pumping of fluid from the reservoir upon oscillation of the pump jack lever 113.

The drive mechanism for oscillating the beam comprises a power or drive unit M, which may include a motor and a gear reducer or chain drive, supported at one end of the base 112 on a pedestal and is provided with a drive shaft 131. A crank arm 132 at one side of the power unit has one end rigidly secured to one end of the drive shaft and a similar crank arm 133 at the other side of the power unit has one end rigidly secured to the other end of the drive shaft, the two arms being disposed in aligned parallel relationship to one another.

A pair of

auxiliary beams

135 and 136 are pivotally connected at one end to the support 111 by

suitable pins

137 and 138, respectively, and journalled in axial alignment in the auxiliary beams. The

auxiliary beams

135 and 136 are connected to the crank

arms

132 and 133, re-

spectively, by

pins

140 and 141 rigidly secured to the v crank arms and extending laterally outwardly into elongate slots 142 of the auxiliary beams. Roller sleeves 141a may be rotatably mounted on the pins and extend into the slots to reduce the friction between the pins and the parallel bearing surfaces 143 and 144 on opposite longitudinal sides of the slots, on which the roller sleeves ride.

It will be apparent that as the drive shaft of the motor rotates and rotates the crank arms, the

pins

140 and 141 will cause the

auxiliary beams

135 and 136 to oscillate about the auxiliary beam pivot pins 137 and 138, respectively, due to their engagement with the bearing surfaces or shoulders defining the slots as the pins move longitudinally of the slots.

The auxiliary beams are also disposed parallel to the pump jack lever 113 and connected thereto by a pair of

pitman rods

146 and 147 and a bracket bar 148. Oscillatory pivotal movement of the auxiliary beams caused by the rotation of the crank arms also causes the oscillating pivotal reciprocating movement of the pump jack lever 113.

The bracket bar 148 is secured to the underside of the pump jack lever 113 at the end thereof which is remote from the horsehead, and is provided at its ends with horizontally disposed pivot pins 150 and 151 which are journalled in spaced pairs of lugs 152 and in the upper ends of the

pitman rods

146 and 147, respectively. The

pitman rods

146 and 147 are connected at their lower ends to the

auxiliary beams

135 and 136, respectively, by pivot pins 153 which are journalled in the lower ends of the pitmans and the brackets 154 secured to the topsides of the auxiliary beams.

Weights

155 and 156 are secured to the ends of the

crank arms

132 and 133, respectively, remote from the drive shaft 131, while

counterbalance weights

158 and 159 are secured to the outer free ends of the

auxiliary beams

135 and 136, respectively.

It will thus be apparent that the auxiliary beams and the pitman rods comprise a mechanical linkage which when activated by rotary movement of the

crank arms

132 and 133 cause the oscillatory pivotal reciprocating movement of the pump jack lever 113.

As shown in FIGURES 5 and 6, the auxiliary beams are disposed parallel with the pump jack lever or walking beam 113 and comprise therewith a first pair of opposite sides of a parallelogram linkage, while the pitman rods form one side of the other pair of sides of the parallelogram, the plane through the pivot pins 115, 137 and 138 forming the other side of such other pair of sides and being preferably disposed substantially parallel tothe pitman rods.

It will also be apparent that the torque on the drive shaft 131 of the gear reducer caused by the weight of the lift rods, the piston and the column of fluid supported on the piston will change during each cycle of the pump. The peak torque load during the upstroke will have a large positive value because of the weight of the lift rods and the fluid supported on the piston, whereas during the downstroke the weight of the lift rods and such fluid as remains on the piston will act to produce a negative torque on the drive shaft. Thus, it will be noted that the greater the weight of the lift rods and the column of fluid being lifted by or supported on the piston, the greater will be the peak torque on the driving shaft during the upstroke and the downstroke in each cycle of operation of the pump, with the consequentially greater loads imposed on the gear reducer drive shaft 131.

To reduce these torque peaks, the

counterbalance weights

158 and 159 are secured to the outer free ends of the auxiliary beams, and the

weights

155 and 156 are mounted on each crank

arm

132 and 133, respectively, at

the end thereof which is remote from the drive shaft 131 of the power unit M, being disposed outwardly from the drive shaft beyond the rollers 141a engaged in the slots 142 of the auxiliary beams. It will be noted that during the upstroke or lifting movement of the pump 110, as illustrated in FIGURE 6, the

crank arm weights

155 and 156 apply or exert a downward force on the

auxiliary beams

135 and 136 complementing the downward force exerted thereon by the

counterbalance weights

158 and 159 secured to the outer free ends of such auxiliary beams, and thereby exert a downward force on the pitman rods and on the end of the walking beam of the pumping jack to which the pitman rods are connected remote from the pump lift rod. Thus, during the upstroke movement of the lift rods, both the crank arm weights and the counterbalance weights assist the power shaft or drive shaft of the motor in lifting the rods 117 and a column of fluid supported thereby above the piston. During the downstroke movement of the elements, as illustrated in FIGURE 5, it will be noted that the

crank arm weights

155 and 156 are positioned between the

pitman rods

146 and 147 and the pivot 137 for the auxiliary beams, and that the effective lever arm of such weights is reduced in length and the force exerted by such Weights acts in opposition to the force of the drive shaft of the motor and exerts a restraining force on the upward movement of the

auxiliary beams

135 and 136, whereby a lesser downward force is applied through the auxiliary beams to the pitman rods and to the end of the pump jack lever to which they are connected.

It will therefore be seen that the arrangement of the auxiliary beam parallelogram structure with the counterbalance Weights secured thereto, in combination with the crank arm weights carried by the crank arms, produces a greater effective downward force applied to the pitman rod end of the pump jack lever during the lifting or upstroke of the pump lift rods, and a lesser or smaller effective load on the pitman rod end of the pump jack lever during the return or downstroke of the pump lift rods. The effective load applied to the pitman rod end of the pump jack lever thus varies in accordance with the load applied to the horsehead end of the pump jack lever during the up and down strokes of the lift rods.

It is to be noted that the

pitman rods

146 and 147 are held and remain in a substantially vertical position, or in a position substantially parallel to the pump lift rods 117, throughout the rotary movement of the cranks and the pivotal reciprocating movements of the pump jack lever and the auxiliary beams. The pitman rods are retained in such position by their connection with the auxiliary beams and the pump jack lever, since the pump jack lever and auxiliary beam are pivotally connected to the stationary upright support 111 and the auxiliary beam and pump jack lever move substantially parallel to each other throughout their arc of movement about their pivotal connections with the support.

It will be readily apparent that both the mass of the counterbalance weights and the crank arm weights and the position of such weights on the auxiliary beam and on the crank arms, respectively, may be varied as desired to vary the effective force exerted on the pitman rods and the pump jack lever thereby.

For the purposes of comparison, a graphic illustration of the torque imposed on the drive shaft by the load on the lift rods and the torque imposed on the drive shaft by a conventional counterbalance means is shown in FIGURE 8 of the drawings, wherein it is noted that the net resultant torque shown in dotted lines becomes a negative torque during a substantial portion of the pump cycle. In contrast to the conventional structure, a pump unit having a parallelogram counterbalance mechanism of this second form of the invention incorporated therein is illustrated graphically in FIG- URE 9, and it is to be noted that the net resulting torque imposed on the drive shaft by the lift rods and by the counterbalance arrangement of the parallelogram linkage and weights on the crank arm and auxiliary beam of this second form of the invention produces a positive torque at all times throughout the entire pump cycle, and therefore produces a more satisfactory desirable result Without overloading of the equipment. Consequently, the parallelogram auxiliary counterbalance structure of this invention reduces fluctuations in the torque applied to the drive shaft, reduces the maximum torque applied thereto and permits less power to be applied to the 'drive shaft for operation of the pump jack than is required for performing the same amount of work with the conventional structure of FIGURE 8.

It is readily apparent that, if desired, a counterbalance weight CW may be applied to each of the auxiliary beams 40 of the form of the invention first described and illustrated in FIGURES 1 and 2. Such a modified structure is shown in FIGURE 10, wherein the auxiliary beam 240 is provided with an extension iarm 241 extending in longitudinal alignment therewith beyond the connecting bearing 240a by means of which the auxiliary beam is connected to the pivot 27 of the crank arm 24 of the unit first described. Obviously, the counterbalance CW in this modification of the invention first described is supplemented by the crank arm weight W in reducing the torque imposed on the transmission driven shaft 28 and the drive shaft 30 by the load exerted on .the horsehead end of the pump jack lever during the upstroke of the pump lift rods, the crank arm weights and the counterbalance weights of this modification coacting in a similar manner as the corresponding counterbalance weights on the auxiliary beams and the crank arm weights on the crank arms of the second form of the invention.

It is further readily apparent that the crank arms 24 of the first form of the invention and the crank arms 132 of the second form of the invention may be modified as shown in FIGURE 11 to position the crank arm weights W of the first form and and 156 of the second fornr with respect to the crank arms to provide a lead or a lag in the effect of the force exerted by the weights through the crank arms on the auxiliary beams of the respective parallelogram counterbalance linkages. In such event, the crank arm could be curved (not shown) or the crank arms may be formed with a crank arm section 200 having openings 201 therein for receiving the crank. pins .27 or140, as the case maybe, and a weight lever arm section 202 on which the crank arm weights 203 may be secured. As shown, the axis line through the crank arm openings 205 for receiving the drive shaft and the openings 2M is disposed at arc angle to the axis line from the opening 205 through the center of mass of the weight 203. Thus, the center of mass of the weights would be moved either in advance or behind the crank pins and the effect of the weights on the auxiliary beams leads the crank pin or lag behind the crank pin as desired.

It will thus be seen that the counterbalance means of both forms of the invention described herein provide for a more uniform distribution of torque without producing the pronounced peaking present in conventional units. In addition, no negative torque is imposed on the drive shaft and a closer balance between maximum and minimum loads is effected.

It will further be seen that new and improved pump jack structures 'have been disclosed herein providing a parallelogram counterbalance means minimizing variations in the load on the power unit or motor drive means of the pump, reducing the torque peaks acting on the power unit and reducing the fluctuation of the torques acting on the unit.

The foregoing description of the invention is explanatory only, and changes in the details of the construction illustrated may be made by those skilled in the art, within the scope of the appended claims, without departing from the spirit of the invention.

What is claimed and desired to be secured by Letters Patent is:

1. A device of the type described including: a support means; an elongate walking beam pivotally mounted intermediate its ends at a fixed point on said support means for reciprocating oscillation about such fixed point in a substantially vertical plane, one end of said walking beam being adapted to be connected to a reciprocably movable vertical load; an auxiliary beam member pivotally mounted at one end on said support for swingable oscillation in a substantially vertical plane about such pivotal connection with said support; a connecting link member pivotally connected at one end to the end of the walking beam opposite said reciprocably movable load and at its other end to said auxiliary beam adjacent its outer swingable end, said link member connecting said elongate walking beam and said auxiliary beam parallel to each other, whereby said elongate walking beam is swingable about its pivotal mounting intermediate its ends by said auxiliary beam; a drive shaft carried by said support and rotatably mounted thereon; a crank arm rigidly secured to said drive shaft and rotatable therewith; connecting means operatively interconnecting said crank arm and said auxiliary beam, whereby said crank arm is connected with said elongate swingable walking beam opposite the end of said walking beam to which said load is adapted to be connected for causing reciprocating oscillating movement of said walking beam upon rotary movement of said crank arm by said drive shaft; and a counterbalance weight means on said crank arm outwardly of said crank arm from said drive shaft beyond the connection of said crank arm with said auxiliary beam for imposing a torque on said drive shaft; and second counterbalance weight means mounted on said auxiliary beam at a point spaced outwardly from the pivotal connection of said auxiliary beam on said support beyond the connection of said auxiliary beam with the connecting link member, said second counterbalance weight means coacting with said first counterbalance weight means on the crank arm for varying the load applied to said walking beam.

2. A device of the character set forth in claim 1 wherein the operative connection between the crank arm and the auxiliary beam comprises: a roller on said crank arm and an elongate longitudinally extending means on said auxiliary beam engageable by said roller, whereby the roller swings the auxiliary beam as the roller is moved by the crank arm, said roller being movable on said auxiliary beam between an extreme outer position outwardly of the auxiliary beam from the point of pivotal connection of the auxiliary beam with the support beyond the point of connection of the connecting link member with said auxiliary beam and an innermost position between said point of pivotal connection of said auxiliary beam with said support and the point of connection of the connecting link member with said auxiliary beam, whereby the effective length of the lever arm of the auxiliary beam varies with the position of the roller in engagement with said elongate longitudinally extending means on said auxiliary beam.

3. A pump jack mechanism including: a support, an elongate walking beam member pivotally mounted intermediate its ends at a fixed point on said support for oscillating about such fixed point in substantially a vertical plane, one end of said walking beam having means for connecting the same to a reciprocably movable load; an auxiliary beam having one end pivotally connected to said support and its other end free for oscillation in a substantially vertical plane; a connecting link member pivotally connected at one end to the end of the walking beam opposite the load connecting means, said connecting link member being pivotally connected at its other end to said auxiliary beam adjacent the free end thereof, the length of said connecting link member and said auxiliary beam being such that the auxiliary beam is disposed parallel to said walking beam and said connecting link member is disposed substantially parallel to the plane of the pivots connecting the walking beam and the auxiliary beam to the support; first counterbalance weight means mounted on said auxiliary beam at a point spaced outwardly from the pivotal connection thereof with the support beyond the connection of said link member with said auxiliary beam; a drive shaft; crank means connected to said drive shaft and rotatable about said drive shaft; means operatively connecting said crank means to said auxiliary beam adjacent the connection of the connecting link member with said auxiliary beam, whereby rotation of said crank means by said drive shaft causes pivotal reciprocating movement of the auxiliary beam and the walking beam connected therewith by said connecting link member; second counterbalance weight means on said crank means disposed outwardly of said crank means from the drive shaft beyond the connection of the crank means with said auxiliary beam, said second counterbalance weight means being moved through a path in which said second weight means is disposed at one extreme outwardly of said auxiliary beam beyond the point of connection of said connecting link member with said auxiliary beam and an inner extreme in which said second counterbalance weight means is disposed inwardly of said point of connection of said connecting link member with said auxiliary beam toward the point of pivotal connection of said auxiliary beam with said support for varying the torque forces imposed on said auxiliary beam by said first counterbalance weight means and said second counterbalance weight means as said crank means is moved; and means for rotating said drive shaft to swing said crank means and cause reciprocating movement of said auxiliary beam and the walking beam connected therewith.

4. A device of the character set forth in claim 3 wherein the operative connection between the crank means and the auxiliary beam comprises a movable connection shiftable longitudinally of said auxiliary beam between an outer extreme outwardly of said auxiliary beam from the pivotal mounting of the beam on the support beyond the point of connection of the auxiliary beam with the connecting link member and an inner extreme inwardly of said auxiliary beam between the point of connection of the auxiliary beam with the connecting link member and the pivotal mounting of said auxiliary beam on the support whereby the eifective lever arm of the auxiliary beam is varied as said connection between the crank arm and the auxiliary beam is moved longitudinally of said auxiliary beam as the crank means is swung.

5. A device of the type described including: a support means; an elongate walking beam pivotally mounted intermediate its ends at a fixed point on said support means for reciprocating oscillation about such fixed point in a substantially vertical plane; a reciprocably movable vertical load carried by one end of said elongate walking beam; an auxiliary beam pivotally mounted at one end to said support at a point substantially vertically below said fixed point and extending parallel to said walking beam and swingable about said pivotal mounting on said support in a substantially vertical plane parallel to said walking beam; a connecting link member pivotally connected at its opposite ends with said walking beam and with said auxiliary beam, one end of said link member being connected to the outer swingable end of the walking beam and the opposite end of said connecting link member being pivotally connected said auxiliary beam adjacent the outer end thereof opposite the connection of said auxiliary beam with said support member, said connecting link member being disposed substantially parallel to the axis of movement of the reciprocably movable vertical load and providing means operatively connecting said walking beam and said auxiliary beam for movement of said beams in parallel relationship as said beams are swung in a reciprocating oscillatory movement in said substantially vertical plane; a drive shaft carried by said support and rotatably mounted thereon; power means for rotating said drive shaft; a crank arm rigidly secured to said drive shaft and rotatable therewith; connecting means operatively interconnecting the rotated end of said crank arm and said auxiliary beam adjacent the connection of said link member with said auxiliary beam, such operative connecting means providing a connection between said crank arm and said walking beam at the end of said walking beam opposite that to which said vertical load is connected for causing reciprocating oscillating movement of said beam upon rotary movement of said crank arm by said drive shaft; first counterbalance weight means mounted on the outer end of said auxiliary beam spaced longitudinally outwardly beyond the connection of the link member with said auxiliary beam and beyond the connection of the crank arm with said auxiliary beam; second counterbalance weight means; and means for connecting said second counterbalance weight means with said drive shaft in an angularly offset relationship to the longitudinal axis of the crank arm and outwardly from said drive shaft beyond the point of connection of said crank arm with said auxiliary beam for imposing a torque on said shaft and the crank arm driven thereby which varies in accordance with the angular offset position of said second counterbalance weight means with respect to the axis of the crank arm, said second counterbalance weight means being movable through a path in which the mass of said second counterbalance weight means is disposed outwardly of the auxiliary beam from the pivotal mounting of said auxiliary beam on said support beyond the point of connection of said connecting link member with said auxiliary beam and beyond the connection of the crank arm with said auxiliary beam and an inner position with respect to said auxiliary beam in which said mass of said second counterbalance weight member is disposed inwardly of the point of connection of said connecting link member with said auxiliary beam and between the connection of the crank arm with said auxiliary beam and the pivotal mounting of said auxiliary beam on said support whereby said first and second counterbalance weights coact for varying the force applied to the walking beam and for limiting the net torque imposed through the crank arm and drive shaft on the power means as the walking beam is oscillated in moving the vertical load.

6. A device of the character set forth in claim 5 wherein the operative connection between the crank arm and the auxiliary beam comprises: a roller on said crank arm and an elongate longitudinally extending means on said auxiliary beam engageable by said roller, whereby the roller swings the auxiliary beam as the roller is moved by the crank arm, said roller being movable on said auxiliary beam between an extreme outer position outwardly of the auxiliary beam from the point of pivotal connection of the auxiliary beam with the support beyond the point of connection of the connecting link member with said auxiliary beam and an innermost position between said point of pivotal connection of said auxiliary beam with said support and the point of connection of the connecting link member with said auxiliary beam, whereby the effective length of the lever arm of the auxiliary beam varies with the position of the roller in engagement with said elongate longitudinally extending means on said auxiliary beam.

7. A device of the type described including: a support means; an elongate walking beam pivotally mounted intermediate its ends at a fixed point on said support means for reciprocating oscillation about such fixed point in a substantially vertical plane; a reciprocably movable vertical load carried by one end of said elongate walking beam; an auxiliary beam pivotally mounted at one end to said support and extending parallel to said walking beam and swingable about said pivotal mounting on said support in a substantially vertical plane with said walking beam; a connecting link member pivotally connected at its opposite ends with said walking beam and with said auxiliary beam, one end of said link member being pivotally connected to said auxiliary beam adjacent the swingable end thereof opposite the connection of said auxiliary beam with said support member, said connecting link member providing means operatively connecting said walking beam and said auxiliary beam for movement of said beams in parallel relationship as said beams are swung in a reciprocating oscillatory movement in a substantially vertical plane, said connecting link member being movable in a vertical plane and parallel to the vertical load at said one end of said walking beam; a drive shaft carried by said support and rotatably mounted thereon; a crank arm rigidly secured to said drive shaft and rotatable therewith; connecting means operatively interconnecting the swingable crank arm and said auxiliary beam adjacent the connection of said link member with said auxiliary beam, such connecting means providing a connection between said crank arm and said walking beam at the end of said walking beam opposite that to which said load is connected for causing reciprocating oscillating movement of said beam upon rotary movement of said crank arm by said drive shaft; and a counterbalance means connected with said crank arm and disposed outwardly of said crank arm from the drive shaft beyond the point of connection of said crank arm with said auxiliary beam, whereby said counterbalance means imposes a weight load on said crank arm which is movable between a point outwardly of said auxiliary beam beyond the point of connection of said connecting link member with said auxiliary beam and a point in which said weight load is disposed inwardly of said auxiliary beam between the point of connection of said connecting link member with said auxiliary beam and the pivotal mounting of said auxiliary beam on said support for imposing a torque on said drive shaft which varies with the torque imposed on said drive shaft by said reciprocably movable load; second counterbalance weight means mounted on said auxiliary beam at a point spaced outwardly from the pivotal mounting of said auxiliary beam on said support beyond the connection 13 of said beam with the connecting link member, said second counterbalance weight means coacting with said first counterbalance means of said crank arm for varying the load applied to said walking beam.

References Cited by the Examiner UNITED STATES PATENTS 735,518 8/1903 Hussey 7441 1,495,218 5/1924 Allen 74--41 1,564,320 12/1925 Callahan 7441 1,592,391 7/ 1926 Stevenson 7441 Reschke 7441 Crites et a1 74603 Jackson 7441 Fuller 7448 Holzer 7441 Holzer 74103 Hartgerin g et a1. 7441 Wineman 7441 Chasteun 7441 Egan et al. 74589 BROUGHTON G. DURHAM, Primary Examiner.

Claims

1. A DEVICE OF THE TYPE DESCRIBED INCLUDING: A SUPPORT MEANS; AN ELONGATE WALKING BEAM PIVOTALLY MOUNTED INTERMEDIATE ITS ENDS AT A FIXED POINT ON SAID SUPPORT MEANS FOR RECIPROCATING OSCILLATION ABOUT SUCH FIXED POINT IN A SUBSTANTIALLY VERTICAL PLANE, ONE END OF SAID WALKING BEAM BEING ADAPTED TO BE CONNECTED TO A RECIPROCABLY MOVABLE VERTICAL LOAD; AN AUXILARY BEAM MEMBER PIVOTALLY MOUNTED AT ONE END ON SAID SUPPORT FOR SWINGABLE OSCILLATION IN A SUBSTANTIALLY VERTICAL PLANE ABOUT SUCH PIVOTAL CONNECTION WITH SAID SUPPORT; A CONNECTING LINK MEMBER PIVOTALLY CONNECTED AT ONE END TO THE END OF THE WALKING BEAM OPPOSITE SAID RECIPROCABLY MOVABLE LOAD AND AT ITS OTHER END TO SAID AUXILIARY BEAM ADJACENT ITS OUTER SWINGABLE END, SAID LINK MEMBER CONNECTING SAID ELONGATE WALKING BEAM AND SAID AUXILIARY BEAM PARALLEL TO EACH OTHER, WHEREBY SAID ELONGATE WALKING BEAM IS SWINGABLE ABOUT ITS PIVOTAL MOUNTING INTERMEDIATE ITS ENDS BY SAID AUXILIARY BEAM; A DRIVE SHAFT CARRIED BY SAID SUPPORT AND ROTATABLY MOUNTED THEREON; A CRANK ARM RIGIDLY SECURED TO SAID DRIVE SHAFT AND ROTATABLE THEREWITH; CONNECTING MEANS OPERATIVELY INTERCONNECTING SAID CRANK ARM AND SAID AUXILIARY BEAM, WHEREBYS AID CRANK ARM IS CONNECTED WITH SAID ELONGATE SWINGABLE WALKING BEAM OPPOSITE THE END OF SAID WALKING BEAM TO WHICH SAID LOAD IS ADAPTED TO BE CONNECTED FOR CAUSING RECIPROCATING OSCILLATING MOVEMET OF SAID WALKING BEAM UPON ROTARY MOVEMENT OF SAID CRANK ARM BY SAID DRIVE SHAFT; AND A COUNTERBALANCE WEIGHT MEANS ON SAID CRANK ARM OUTWARDLY OF SAID CRANK ARM FROM SAID DRIVE SHAFT BEYOND THE CONNECTION OF SAID CRANK ARM WITH SAID AXUILIARY BEAM FOR IMPOSING A TORQUE ON SAID DRIVE SHAFT; AND SECOND COUNTERBALANCE WEIGHT MEANS MOUNTED ON SAID AUXILIARY BEAM AT A POINT SPACED OUTWARDLY FROM THE PIVOTAL CONNECTION OF SAID AUXILIARY BEAM ON SAID SUPPORT BEYOND THE CONNECTION OF SAID AUXILIARY BEAM WITH THE CONNECTING LINK MEMBER, SAID SECOND CONTERBALANCE WEIGHT MEANS COACTING WITH SAID FIRST COUNTERBALANCE WEIGHT MEANS ON THE CRANK ARM FOR VARYING THE LOAD APPLIED TO SAID WALKING BEAM.