US2408200A - Walking beam structure - Google Patents

Description

Sept. 24, 1946. R. G. DE LA MATER 7 8,

7 WALKING BEAM STRUCTURE Filed Aug. 50, 1944 2 Sheets-Sheet- Z9; 6579-: :8 l I I E i I I Z0 0 1' 1 INVENTOR FOBMTG'DEMMQTEK ATTORNEY 8 Sept. 24, 1946. R. 6. DE LA MATER WALKING BEAM STRUCTURE -F iled Aug. 30, 1944 2 Sheets-Sheet 2 INVENIOR Foes/5w 6. D: in MA 723 Patented Sept. 24, 1946 WALKING- BEAM STRUCTURE Robert G. De La Mater, Parkersburg, W. Va., as-

signor to The Parker sburg' Rig & Reel-Company,'Parkersburg, W. Va., a. corporation of West Virginia Application August 30, 1944,. Serial 1x0 551308.

This invention relates to walking beam structures and' more particularly to a walking beam ior oil well pumping units.

In, oil well pumping unitsit is the common practice to make a walking beam of a single rolled beam section with acompensator or other means at the. front end to obtain a relatively straight line motion ofthe pump rod. A Samson postis l'ocated intermediate the. ends of the beam andis provided with a rocker bearing in which is, arranged a trunnion connected to the walking beam. At the back or tail end of the beam is mounted the upper pitman assembly through which the walking beam is rocked, such assembly usually" including a horizontal cross beam with vpitman stems extendingdownwardly from the beam to the wrist pin bearings to which they are n cted-r It is desirable in an apparatus of this character to empl a c n ruction ner ly ref rr d as a three point in line beam, i. e., a beam arrangement wherein the center lines of the upper pitman bearing and the Samson post jbearing and the center line of travel over the com pensator at the front ofthe beam are all in the", same horizontal plane when the walking beam is' horizontal. This istheideal arrangemerit but its use is not always practicable without incurring excessive expense in manufacture, and the fabricating problems areoften such as to render" the selling. price of the unit excessive.

The advantages of the three point in line beam are. well known in the art. With any other arrangement 'a different pumping motion will be obtained, depending upon Whether the crank shaft is rotated clockwisev or counterclockwise; i. e;, greater angular rotation of the crank shaft. Willbe required on the upstroke than on the downstroke, or. vice versa, and the acceleration and deceleration at the top and bottom of each stroke will differ. line. beam and with the center line of thecrank shaft" directly below the upper pitman'bearing when the walking beam is horizontal, the unit can be. operated in either direction without changing the, character of the pumping stroke.

wit the. ideal a rangement r d t t is the pr tice in s me. ca s t arrange the Sams post hearin so that its aXis p s e th h the center line of the beam, in which case it is necessaryto provide'space between the legs of the Samson post and to support separate bearings on each side of the beam for clearance with the walking-beam, or to shorten the Samson post and a hear n at eaehsid f th b m w h Claims.

With a three point in the boxes of the bearings extending at a considerable distance above their bases to secure the same clearance. Neither arrangement adds to the stability and rigidity of the assembly, although such location of the Samson post bearing axis istheoretically highly desirable.

Moreovergthe capacity of a walking beam of conventional r-beam or wide flanged rolled sections is definitely limited by the ratio of the unsupported length vof the beam to the width of compression flange thereof, and with a single rolled section for a-walking beam there is no possible way of reducing the unsupported length of the beam between working centers. It is also impossible to obtain rolled beam sections with- .out the usual rolling tolerances for out-ofsquarenessor parallelism of the flanges and without camber 0r out-of-straightness in their lengths. Consequently, in the fabricating of a conventional walking beam it is necessary in the fitting up of the bearings to compensate for these conditions. For example, where'the Samsonpostbearingis bolted to the bottom flange of the beam it is necessary to provide some selfalign ing feature in the pitman assembly and also to fabricate the nose and make necessary adjustments in the fabrication so that the pump rod hanger will travel in a plane at right angles to the Samson post bearing. Even with the most careful fabrication further' distortion sometimes occurs in thebeam after a unit is put into operation. Consequently, it is'not unusual forthe tail end of a walking beam to travel up and down in a slightly elliptical or figure lipath, instead of in a vertical line. The same thing is true of the nose or front end of the beam;

In, machining the keyways in crank shafts of pumping units and in the cranks a manufacturing tolerance must'be allowed, and accordingly one crank usually leads, the, other to a slight extent. Consequently, particularly at the mid-position of the, stroke, one wrist pin usually is sl ghtly er han the t thus requiring t e use at comp n a ing m a s to avoid th i g of stres es n t pitman as em ya As i ll. know t. is n o l actice to, counterweight the walking beams of oil wellv pumping units and such counterweights usua ly a e arr n ed a j cent each other along the walk ngbeam- S ch eount rweie ts a e at varying distances frornthe axis of the Samson post bearing and are consequently not uniformly efiective. When adding'beam weights to such a walkin eam it i necessa y o ef to a tab or to know the proper ratios withrespect tobeam 3 lengths so that the effective counterbalancing of the walking beam can be provided.

An important object of the present invention is to provide a novel walking beam construction which departs substantially from conventional practice, the 'beam structure being such as to facilitate a, three point in line arrangement.

A further object is to provide a walking beam formed of two structural members diverging from the nose end of the beam and effectively laterally braced to each other, thus greatly improving the general performance characterists of the beam over a conventional single I-beam or H-beam arrangement, the present invention providing for a walking beam of greater capacity and rigidity with the same weight of steel.

A further object is to provide such an improved walking beam wherein the loads are equally'and uniformly transmitted to the two beam members without imposing any concentrated stresses.

A further object is to provide a walking beam of the character referred to whichpossessessuch characteristics as to make it possible in fabricating the structure, to adjust for any camber or out-of-squareness of the two beam members, and also to make all necessary-provisions to obtain true alignment of the three working points. of the beam. 7

A further object is to provide novel arrangement wherein the use of self-aligning bearings at the upper ends of the-pitman stems provides for a greater degree of self-alignment than is possible with conventional arrangements.

A further object is to provide a beam structure of the general character referred towherein all of the counterweights employed which are of the same size provide the identical amount of effective-counterbalance weight. A

Other objects and advantages of the invention will become apparent from the course of. the following description.

In the drawings I have shown one embodiment of the invention. In this showing- Figure 1 is a side elevation of a pumping unit showing a walking beam constructedinaccordance with the present invention,

Figure 2 is an enlarged fragmentary transverse sectional view on line 2-2 of Figure 1,

Figure 3 is a plan view of the Walking beam and associated elements, parts being broken away,

Figure 4 is a transverse sectional view on line 4--4 of Figure 3,

Figure 5 is a plan .view of theJSamson post bearin saddle, and

Figure 6 is a transverse sectional .viewon, line 66 of Figure 4., A

Referring to Figure 1, the numeral I designates the base of a pumping unit at .one end of which is arranged an upstandingSamson post indicated as a whole by the numeral I I and comprising opposite vertical legs I2 and opposite in-- clined legs I3 converging toward the legs .I2 and fixed at their upper ends. by welded or similarly attached plates I4. A cap plate I is arranged over the top of the Samson .post and extends downwardly along the sides thereof and is welded or otherwise secured to theplates I4 and to the legs I2 and I3, The base I0 is provided with .a prime mover I6 driving conventional cranks I! through any suitable type of reduction gearing I8, the free ends of the cranks being connected .to the bearings I9 at the lower ends of ,pitman stems 20.

Thewalking beam'forming the subject matter of the present invention is indicated as a whole 4 by the numeral 2I and comprises opposite beam sections 22 preferably of rolled channel section as shown in Figures 2 and 4. The beam sections 22 converge toward the front or nose end of the beam and are rigidly fixed with respect to each other by the attachment thereto of any suitable type of compensator 23 for providing a straight line vertical motion of a rod hanger 24.

The means for mounting the walking beam 10 with respect to the Samson post is shown in Figures 1, 3, 4 and 6, most of the details of such mounting being shown in Figure 4. Referring to such figure, a horizontal relatively heavy shaft 26 is provided-at each end with web plates 21 welded thereto, and these plates and the ends of ,the shaft 26 are welded in turn to preferably diamond-shaped plates 28. In the fabricating of the beam, the edges of each plate 28, the preferably diamond-shape of which is shown in dotted lines in Figure 1, are welded along spaced lines following the profile of each plate 28, the welding preferably being discontinuous toavoid any possible weakening of the channel sections 22. Centrally of its length, the shaft 26. fits within a half-bushing 29 and is keyed thereto as at 30,

bolts 3! extending through the shaft26 to secure it to the half-bushin 29. It will become apparent that the member 29 rocks with the shaft 26. The half-bushing 29 rocks in a bearing saddle 30 32 mounted on the cap plate I 5 and secured thereto by bolts 33 (Figures 3 and 6). The bearing saddle 32 has an inner semi-cylindrical bearing surface 34 engaged by the half-bushing 29. and the latter terminates at points spaced from the 35 longitudinal ends of the bearing surface 34 as shownin Figure 4. The spaces at the .ends. of the half-bushing 29 are filled by semi-cylindrical filling and sealingelements35 each of which is provided with aperipheral flange 36seating in a 40 corresponding groove 3l.formedinthe saddle 32 (Figure 4) A bearing cap 40 is arranged over the shaft and is substantially semi-cylindrical in shape with its inner surface 4| of greater radius than the outer surface of the half-bushing to provide a semi-cylindrical space. 42 (Figure 6) in which the ends of the half-bushing 29 are free to rock during the rocking of the beam structure. The cap 40 is flanged as at 43 and the bolts 33 pass through these flanges- A removable plug 44 is carried by the cap 40 for the introduction of lubricant into the space 42.

The saddle 32 is formed with .cored-out lubricant reservoirs 46 (Figure 6) and the saddle 32 is grooved as at 41 to connect the reservoirs 46 to each other and open them to access to the outer or bottom surface of the half-bushing 29. When the apparatus is assembled, the reservoirs 46 are filled with lubricant before. the cap 40 is placed in position To prevent the loss of lubricant endwise of theshaft 26, a sealing-ring 48-surrounds the shaft and is arranged in complementary grooves and 50uformed in the cap 40-and'in the sealing members 35 respectively.

The structure shown in Figures 3 and 4.greatly assists in the proper fabrication .of the. walking beam and increases the efficiency of the operation and maintenance of the apparatus. It will be noted that therelatively heavy shaft, with the bracing plates 21 and attaching plate 28, serves to form a rigid connectionbetween the beam sections 22,- thus greatly increasing the stability of the walking beam. Moreover, in the fabrication of these elements, any out-of-.-trueness of the beam elements 22 in themselves and A highly: advantageous'method of connecting the beamsections and transmitting pitman forces to the beamis shown in Figures 2 and 3. At a 'pointspaced from the rear end of the beam (Figure 3) a relatively heavy steel X10855 extends transversely across the beam and through openings tt formed in the respective :bearn sections 22. This tube is welded as at 51 to an attaching plate 58 which, in turn, is welded as at 59 to the webof each beam section 22. These parts maybe fabricated for the rigid connection and trueing of the beam sections 22 at the points where the tube 55 passes therethroughprior to the placing of a shaft 66 in each end of the tube. The ends of the tube are drilled out as at 6| for the press fitting of theshafts 69' and the latter are positively secured in the tube 55'by bolts "62. Each-shaft 66-has self aligning motion-transmitting'connection with one of the pitman stems 2U andsince these connections are identical, only one need be described. Referring to Figure 2, it

will be noted that each shaft 69 is reduced as at Bil-to pass freely through a somewhat larger openingtiiformed in a housing 66' and a sealing ring 61' prevents the escape of lubricant past the shaft section 64. Within the housing 66 is formed a cylindrical recess 68 and complementary sections 69 form a spherical bearing which is arrangedin the recess 65. The complementary sections SSarenormaI-ly spaced from each other for a purpose to be described. Beyond the section, the shaft 66 is further reduced insize' asat Ill and such reduced shaft section carries a bearingmember H formed as a section of a sphere and mounted in the complementary'beari'ng sections 69'to rotate and rock therein.

A- cap 72 is" secured to the housing 66 by bolts 13- and interposed shims 'Mlimit the inward movement'of the cap I2 upon the tightening of the bolts 13. As the bearing surfaces of the elements '69 'and H become worn, one or more shims 14 may-be removed, whereupon the replacing of the ca 12 and the tightening of the nuts 13 will' move the outer complementary member 69 toward the-other such member to take up play between the-parts. The cap 12 is bowed out to provide -a-'lubrioant space and a removable plug 16 pro- 'ndes access to the space 15 for the introduction of" lubricant thereinto.

*"I'lie upper end of theassociated pitman stem 2'6" carries a ring 16 having a conical inner sur- "face 19* fitting the corresponding radially outer surface 86 of the housing 66. A plurality of bolts is "employed for tightening the ring 18 on the surface-80. Each bolt is indicated by the numeral 61" and is provided with a conventional nut 82 and with a head 83, one end of which projects radially inwardly as at 84 to engage the surface 85 of the housing 66 whereby the nuts 82 may be tightened. Obviously, the loosening of the nuts 82 and the swinging of the heads 83 permits the ring F8-Qt0 be detached from the housing 66 when desired,- and the cap 12 may be removed for any elements are fabricated, but also as a support for a plurality of counterweight's 89. Each counterweight is preferably formed of complementary sections 96 divided centrally as at 9|, the sections of each counterweight being secured together by any suitable means, as by bolts 92. In practice, the counterweights are specifically designed to facilitate their connection to the cross member 88, but the particular form of the counterweights is of no importance per se in connection with the present invention.

The operation of the walking beam structure will be largely apparent'as a result of the foregoing description. Instead of using a single rolled structural beam for the walking beam, two lighter structural members are employed, these mem bers preferably but not necessarily being of channeled cross section. The beam structure is generally triangular inv shape, the beam elements22 converging toward the nose end of the beam. to permit the efficient mounting of the pump rod hanger. The beam elements 22 are sufficiently spread at the Samson post to permit thebearing of the latter to be placed between the beam sections. The spread at the. plane of connection of the pitman assemblies is substantially greater, being sufficient so that the pitman stems may extend directly downwardly to the wrist pins at their conventional positions while still transmitting forces to the walking beam at points in proximity to the respective beam sections 22.

The arrangement of parts is further advantageous in that the counterweights are mounted on a cross member which acts as a tie between the beam sections 22 at the rear end. thereof. With this arrangement, each set of beam weights of the same size provides the same amount of effective counterbalance weight, as distinguished from..the prior arrangement referred to.

The present construction also facilitates the three point in line arrangement, the axis of the shafts 60, the axis of the shaft 26 and the point of hanging of the well rod Weights being in a common plane when the beam is horizontal and the center line of the crank shaft I! (Figure 1) being directly below the axis of the shafts66. Accordingly the unit can be operated with equal effectiveness in either direction of rotation of the crank shaft 11.

The two structural members forming the principal elements of the beam, namely the members 22, are laterally braced at the nose, at theSamson post, at the upper pitman assembly, and at the rear end of the beam by the member 88 As a consequence, length/flange width ratiov is materially improved over that obtained by means of a single I-beam or'H-beam arrangement and greater capacity and rigidity can be obtainedWi-th the same weight of steel.

The trunnion for the Samson post bearing and the pitman assembly are so designed and welded into the complete beam assembly that the loads are very equally and evenly distributed to the two beam members without the imposing of any concentrated stresses. From the Samson post trunnion 26 and the pitman trunnion's 66, the uniform distribution of forces to the beam sections 22 is assisted by the use of the plates 28 and 58 welded to the beam sections. The welding of the parts in the manner described makes it possible to adjust for any camber or outof-squareness of the rolled channel sections and also makes it possible to obtain true alignment of the three working points of the beam.

The construction described adds greatly to the lateral stiffness of the beam assembly and substantially eliminates weaving during operation. With the present arrangement the necessity for a complete self-aligning arrangement of the pitman assemblies is somewhat alleviated, it being unnecessary to employ the usual cross member to which the upper pitman assemblies are connected and mounted to rock on an axis coincident with or parallel to the plane of the walking beam.

It is to be understood that the form of the invention herewith shown and described is to be taken as a preferred example of the same and that various changes in the shape, size and arrangement of parts may be resorted to without departing from the spirit of the invention or the scope of the subjoined claims.

I claim:

1. A walking beam for oil well pumping rigs and the like comprising a pair of structural members spaced substantially throughout their lengths and fixed with respect to each other at the well end of the beam, and rigid means fixed to said structural members at a point substantially spaced from the well end of the beam, said rigid means being arranged within the space between said structural members and projecting therethrough for connection with pitman means, and a trunnion arranged in the space between said structural members and rigidly connected at its ends thereto between said rigid means and the well end of the beam to form a part of a rocking support for the beam.

2. A walking beam for oil well pumping rigs and the like comprising a pair of structural members spaced substantially throughout their lengths and fixed with respect to each other at the well end of the beam, and rigid means fixed to said structural members at a point substantially spaced from the well end of the beam, said rigid means being arranged within the space between said structural members and projecting therethrough, and a trunnion arranged in the space between said structural members and rigidly connected at its ends thereto between said rigid means and the well end of the beam, a Samson post bearing receiving said trunnion to support the beam for rocking action, and selfalining bearing means having connection with the projecting portions of said rigid means and through which power is transmitted to the beam to rock it on the axis of said trunnion.

3. A walking beam for oil well pumping rigs and the like comprising a pair of structural members spaced substantially throughout their lengths and fixed with respect to each other at the well end of the beam, and rigid means fixed to said structural members at a point substantially spaced from the well end of the beam, said rigid means being arranged within the space between said structural members and projecting therethrough, and a trunnion arranged in the space between said structural members and rigidly connected at its ends thereto between said rigid means and the well end of the beam, a Samson post bearing re- 8 ceiving said trunnion to support the beam for rocking action, a spherical element fixed to said rigid means outwardly of each side of the beam, and a spherical socket receiving each spherical element for transmitting power therethrough to the beam to efiect a rocking movement thereof.

4. A walking beam for oil well pumping rigs and the like comprising a pair of structural members spaced from each other substantially throughout their lengths and fixed with respect toeach other at the well end of the beam, each member comprising a vertical web, a trunnion arranged perpendicular to the horizontal axis of the beam at a point spaced from the well end of the beam and arranged between said structural members, and plates rigidly fixed to the ends of said trunnions, said plates lying against the webs of the respective structural members and fixed thereto, said trunnion forming a part of the means for supporting the beam for rocking movement.

5. A walking beam for oil Well pumping rigs and the like comprising a pair of structural members spaced from each other substantially throughout their lengths and fixed with respect to each other at the well end of the beam, each member comprising a vertical web, a trunnion arranged perpendicular to the horizontal axis of the beam at a point spaced from the Well end of the beam and arranged between said structural members, plates rigidly fixed to the ends of said trunnions, said plates lying against the webs of the respective structural members and fixed thereto, said trunnion forming a part of the means for supporting the beam for rocking movement, and rigid means arranged in the space between and rigidly fixed to said structural members at a point spaced longitudinally along the beam from said trunnion, said rigid means having portions projecting through said structural members and extending outwardly beyond opposite sides or the beam for connection with pitman means.

6. A walking beam for oil well pumping rigs and the like comprising a pair of structural members spaced from each other substantially throughout their lengths and fixed with respect to each other, each member comprising a ver tical web, a trunnion arranged perpendicular to the horizontal axis of the beam and arranged between said structural members, plates rigidly fixed to the ends of said trunnions, said plates lying against the webs of the respective structural members and fixed thereto, a bushing member carried by said trunnion, and a bearing in which said bushing member is adapted to rock, said bearing having a lubricant cavity therein extending through the bearing face of said bearing to supply lubricant to said bushing member.

7. A walking beam for oil well pumping rigs and the like comprising a pair of structural members spaced from each other substantially throughout their lengths and fixed with respect to each other, each member comprising a vertical Web, a trunnion arranged perpendicular to the horizontal axis of the beam and arranged between said structural members, plates rigidly fixed to the ends of said trunnions, said plates lying against the webs of the respective structural members and fixed thereto, a half-bushing fixed against the bottom of said trunnion, a bearing member having a semi-cylindrical bearing face rockably supporting said half-bushing, said bearing terminating approximately in the horizontal plane of the axis of said bushing when cylindrical face to supply lubricant to said halfbushing, and a cap for'said bearing having a portion normally closing the open top of said cavity and having an inner face concentric with and at least as large in diameter as the radially outer face of said half-bushing to provide a space in which the edge portions of the latter are adapted to swing.

8. A walking beam for oil well pumping rigs and the like comprising a pair of structural members spaced from each other substantially throughout their lengths and fixed with respect to each other at the well end of the beam, each member comprising a vertical web, a trunnion arranged perpendicular to the horizontal axis of the beam at a point spaced from the well end of the beam and arranged wholly between said members, attaching plates rigidly fixed to the ends of said trunnions, each plate being parallel to and lying against the adjacent portion of the web of the adjacent structural member and secured thereto, and web plates fixed to said trunnion adjacent each end thereof and to the adjacent attaching plate to brace the latter and the associated structural member relative to said trunnion, said trunnion forming a part of the means for supporting the beam for rocking move- 7 ment.

9. A walking beam for oil well pumping rigs and the like comprising a pair of structural members spaced from each other substantially throughout their lengths and fixed with respect to each other, each member comprising a vertical web, a trunnion arranged perpendicular to the horizontal axis of the beam and arranged wholly between said members, attaching'plates rigidly fixed to the ends of said trunnions, each plate being parallel to and lying against the adjacent portion of the web of the adjacent structural member and secured thereto, web plates fixed to said trunnion adjacent each end thereof and to the adjacent attaching plate to brace the latter and the associated structural member relative to said trunnion, said trunnion being arranged approximately midway of the height of the beam, a bushing fixed against the bottom of said trunnion, and a bearing receiving said bushing to support the beam for rocking movement.

10. A-walking beam for oil well pumping rigs and the like comprising a pair of structural members spaced from each other substantially throughout their lengths and fixed with respect to eachother at the well end of the beam, each member comprising a vertical web, a trunnion arranged perpendicular to the horizontal axis of the beam at a point spaced from the well end of the beam and arranged wholly between said members, attaching plates rigidly fixed to the ends of said trunnions, each plate being parallel to and lyin against the adjacent portion of the webof the adjacent structural member and secured thereto, web plates fixed to said trunnion adjacent each end thereof and to the adjacent attaching plate to brace the latter and the associated structural member relative to said trunnion, said trunnion forming a part of the means for supporting the beam for rocking movement, a rigid member arranged wholly within the vertical limits of said structural members at a point spaced longitudinally along the beam from said trunnion, said rigid member extending through and beyond both structural members, an attaching plate fixed against the inner web of each structural member and surrounding said rigid member and, secured thereto, and means for transmitting forces to the projecting portions of said rigid member to rock the beam.

ROBERT G. DE LA MATER.

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