US2522742A - Crosshead - Google Patents

Description

Sept. 19, 1950 L. A. BLACKBURN 2,522,742

CROSSHEAD Filed June 30, 1945 IN VENTDR. ,zwwv W WM 4 MM Patented Sept. 19, 1950 UNITED STATES PATENT OFFICE CROSSHEAD Luther A. Blackburn, Lynwood, Calif. Application June 30, 1945, Serial No. 602,588

3 Claims. 1

This invention relates generally to crossheads, and more specifically contemplates mechanism for efiecting transmission of power between apparatus, reciprocable in straight line motion, and, alternately, the opposite reaches of endless chains.

While the utility of crossheads is well understood in the prior art, the specific construction of such devices varies widely in accordance with special requirements. However, universal application of the crosshead principle to mechanical units otherwise adaptable for its utility has been greatly restricted due to the inability to combine sufficient strength and the ease of operation in units having the degree of flexibility requisite for compensation of the misalignment of parts due to wear, inaccurate adjustment, and particularly variations in the distribution or balancing of the load.

A principal object of the present invention is to provide a crosshead of novel construction, adapted particularly to oil well pumping assemblies as a means for transmitting the power of endless drive chains to the polished rod of a well pump.

More specifically, it is a highly important object hereof to provide a device of the character above alluded to embodying a pair of roller blocks movable laterally in guide members into alignment with different reaches, alternately, of pairs of endless chains, respectively, by which the cross-head is actuated, in combination with a fiex iblc connective between the chains and roller blocks.

Another object is to provide a roller block comprising one or more rollers movable between parallel wear plates of a crosshead to which the power motive, received from a shaft projecting through the block, may be transmitted in a direction at right angles to the line of movement of the block relative to the plates, the shaft being rotatable and tiltable in any direction with respect to the axis of the block without affecting of the crosshead, adaptability of the apparatus to be constructed primarily of common structural shapes such as channels, I-beams, plate, tubing, and the like, contributing to economy of manufacture, facility of assembly, maximum strength per unit weight, and durability, will be apparent from the following description read. in the light of the accompanying drawings, in which:

Fig. 1 is a perspective view of a preferred form of crosshead, omitting the roller blocks;

Fig. 2 is an elevation of the complete assembly, illustrating the relationship of the drive and counterweight chains and vertical guide rails be-- tween which the unit is reciprocated;

Fig. 3 is a vertical view taken in two different planes, illustrating particularly the construction of the flexible bearingsof the roller blocks, and the openings in the crcsshead for extension of the polished pump rod in the crosshead;

Fig. 4 is a vertical section through the swivel washer of the polished rod support through which compensation for misalignment between the rod and crosshead is effected;

Fig. 5 is a reduced elevation of a modified form of crosshead;

Fig. 6 is a vertical sectional view through the form of the invention illustrated in Fig. 5 and taken in two different planes to show the polished rod support and the arrangement of the roller block elements.

Referring to the drawings in detail, the nu merals of which indicate similar parts throughout the several views, it designates an I-beam forming the lower horizontal support for the structure, and II a channel superimposed above and in parallel spaced relation with I-beam It The channel II and I-beam it! are held in rigid spaced relation by guide shoes l2 arranged between corresponding opposite ends of the structure. Guide shoes 12 are formed with vertical slots I3 in their outer faces, soul-spaced from opposite sides thereof, respectively, to accommodate the parallel flanges of stationary T-iron guides I4 between which the orosshead is to reciprocate. l5 indicates a split felt block housed in the upper end of each guide shoe 52 with parts thereof arranged on either side of slot it for the retention of a quantity of oil by which the T-iron guides I 4 may be lubricated. The upper surface of the web of I-beam Hi provides support for a pair of wear plates arranged in spaced, parallel relation with longitudinal edges contiguous with opposite upwardly-directed flanges oi the beam. Similarly, a second pair of wear plates H are suspendedfrom the underside of channel I l by screws or the like, and in a similar manner are disposed in spaced relation. Channel, Hp,

I-beam l0, and guide shoes [2 with the ends of wear plates I6 and H interposed therebetween, are secured rigidly together by tie rods 18. In order to reinforce the center of the structure and maintain the critical distance between the upper and lower pairs of wear plates i6 and I1, I provide a pair of spacing tubes [9- which are secured between vertically aligned pairs of wear plates of the I-beam Id and channel Ii, respectively, and are arranged in equi-spaced relation from respective guide shoes I2.

Welded or otherwise secured in contiguous relation with the upwardly-directed flanges of channel II are a pair of plates 2!) comprising part of a counterweight attachment, hereinafter more in detail described. The vertical disposition of plates 20 is reinforced by end members 2|, arranged in contiguous relation with the inner faces of guide shoes i2, respectively. At each side of the center of the crosshead, a pair of parallel plates 22 are secured in spaced relation between the elongated plates 20 to form boxlike constructions equi-spaced from the guide shoes, respectively, for the reception of the ends of counterweight chains 23, where such expedients are desirable for use. A pair of verticallyaligned holes 24 perforate each side of each box, with each hole in tranverse alignment with one of the holes in the opposite plate 2%] for reception of the ends of a pin 25 on which the ends of a counterweight chain 23 may be pivotally attached by means of a special chain attachment 23a. Each attachment 23a comprises a block having a bifurcated lower portion, the bifurcations being perforated to receive one of pins 25. The upper end of each attachment 23a is also furcated to accommodate therebetween the various lower end links of the counterweight chain 23 to be associated therewith, the furcations of attachment 23a and the end links of the chain being pivotally connected by a link pin 2 a. It will be observed that by providing two sets of horizontally aligned holes 24 in each box for mounting pins 25, an adjustment is permitted for the length of the chain 23. Intermediate the ends of the crosshead, a supporting plate 25 is secured across the upper edges of plates 29, having a' central opening 21 countersunk for the reception of a swivel collar 28. The upper surface of the annular washer 28 is concave for operative cooperation with a complementary convex undersurface of a washer 29 superimposed thereon. Vertically aligned with opening 21 in supporting plate 26 is a pair of openings 39 in the web of channel II and I-beam l0, respectively, for the accommodation of a polished rod 3| of an oil pump for the operation of which the apparatus is particularly adapted. The sucker rod 3| extends between wear plates carried by the I-beam and channel, respectively, and projects upwardly through the washers 28 and 29, ciroumscribing opening 21 in plate 26.

31a indicates a coupling between sections of the polished rod 3|. It will be understood that opening 21 in plate 26 and openings 38 in the channel and I-beam, respectively, are sufliciently large to permit the withdrawal of the polished rod coupling 3Ia therethrough. It will thus be observed that collar 28 and washer 29 function to center the polished rod with respect to the crosshead during operation. The weight of the rod string 3| is transmitted to the crosshead through a conventional type polished rod clamp, generally indicated by the numeral 32. It will be understood that the openings 2'! and 30 in the I-beam and channel and plate are of sufficiently greater diameter than that of polished rod 3| whereby slight variations in the preferred right angular relation of the crosshead with respect to the polished rod due to oscillation of the crosshead in operation may be compensated by relative shifting of the washer 29 on washer 28 so as to permit the polished rod to maintain a vertical position throughout the cycle of operation The embodiment illustrated is adapted to be actuated by four chains 33, one reach of each of which is attached by a flexible connection to one end of a pair of roller blocks 34. Each roller block 34 comprises a pair of rectangular plates 35 arranged in spaced relation for the support between each pair of opposed corners thereof, of a roller 36, hereinafter more in detail described. Each of rollers 36 of each block comprises a cylinder mounted upon bearings 31 carried by a coaxial pin 33, having its ends secured in the opposed plates 35, bearings 31 being spaced apart by a sleeve 39 encircling pin 38. The disposition of plates 35 of each roller block is maintained by a centrally located cylinder 49 having its ends secured in the plates 35.

Housed within cylinder 40 is a self-aligning roller bearing cartridge ll of conventional construction, through which a shaft 42 projects with its ends extending laterally from opposite ends of the cylinder for alignment with reaches of the actuating chains 33 disposed on either side of the crosshead. Shaft 42 and the inner elements of the bearing 4! are rotatable with respect to roller block 34 in order to follow chains 33 over the sprockets (not shown) by which the chains are supported and actuated.

On each end of shaft 42 of each roller block 34, a master link fitting 43 is telescopically connected for pivotal association with one of chains 33 at the corresponding side of the crosshead. The construction in detail of master link fitting 43 is not described nor illustrated, but is fully disclosed and claimed in my co-pending application Serial No. 602,911, filed July 2, 1945.

It will suflice to point out that due to the telescopic connection between the master links 43 and shafts 42, lateral oscillation of chains 33 during actuation of the crosshead will be absorbed without any lateral strain on the bearing cartridge 41 or roller block 34, any tendency toward displacement of the block being resisted by the upstanding flanges of I-beam ID. The dimensions of roller block 34 and disposition of the upper and lower pairs of rollers 36 is such to assure minimum play between the upper and lower wear plates 16 and 17 at the ends of the stroke of the crosshead. The difliculty of initial adjustment and maintenance of the horizontal relationship of the apparatus during operation will be appreciated. However, the utility of the self-aligning roller bearing cartridge 4! enables each of shafts G2 to tilt in any direction independently of one another to compensate for any inaccuracies in preadjustment of chains 33, as well as for unequal distribution of the load or small failures of any of the elements.

In Figs. 5 and 6 I have illustrated a modified form of the crosshead of my invention, in which the upper channel I I and counterweight chain attachment assemblies are identical with the embodiment of Figs. 1-4 inclusive. The lower wear plates [6, however, are supported by an inverted channel 44 in place of I-beam ll) of the embodiment first described.

The web of channel 44 is formed with a pair of elongated slots 44a at either side of the center of the crosshead and between the wear plates to permit grit, dirt or other foreign matter which would otherwise tend to accumulate on the lower wear plates I6 and interfere with most efficient operation, to fall through slots 44a and from the crosshead. In all other material respects the crosshead of the respective embodiments, exclusive of the roller blocks, are substantially the same. As indicated in Fig. 6, the roller blocks 4-5 consist of a cylinder 46 having a peripheral flange at either end adapted to overhang the corners of the respective upper and lower channels II and 44 to resist displacement laterally of the crosshead. The shaft 42 adapted to carry the master links 43 on either end projects through the self-aligning roller bearing cartridge 4| as hereinabove described. The bore of cylinder 46 is of a diameter to accommodate shaft 42 and bearing cartridge 41, the latter being non-rotatably engaged intermediate the ends of cylinder 46 whereby the cylinder and shaft may freely rotate relative to one another. As in the embodiment first described, shaft 42 is free to tilt in any direction to compensate for inaccurate preadjustment or developed misalignment of the parts. The rotatable relationship between shaft 42 and roller cylinder 46 ermits the cylinder of the respective rollers 5 to roll on either the upper or lower wear plates [6 and ll of the crosshead into alignment with the opposed upwardly and downwardly moving reaches of chains 33 by which they are actuated on alternate strokes, and further permit shaft 42 and master links 43 carried thereby, to turn with chains 33 over the sprockets of the chain mechanism, so as to make one full revolution with each complete cycle of movement of the crosshead.

It will thus be seen that I have provided a symmetrical crosshead construction particularly adapted for vertical reciprocatory movement in response to actuation by four endless chains, movement in two opposite directions of which is transmitted to the crosshead through a pair of roller blocks movable laterally of the crosshead into alignment alternately with opposite reaches of respective chains by which they are actuated, respectively, by means of a flexible connection between each of the chains and one of the roller blocks, the flexibility of the association between the blocks and chains being effective to compensate automatically and immediately for variation in the preferred preadjustment of the apparatus.

It will be understood that while the embodiments illustrated and described comprising preferred forms of my invention are constructed for utility with and application to specific apparatus, namely an oil well pumping unit, the structure lends itself to modification in many particulars to enable its adaptation for other purposes, e. g., numerous changes in size, design, shape, number and proportion of the various parts maybe made, a single spacing cylinder through which the polished rod may be extended can be substituted for the tubes I9; and that conventional more critically adjustable attaching means may be provided for connecting the counterweight chains to the crosshead, all without departing from the spirit of my invention as defined in the appended claims.

What I claim and desire to secure by Letters Patent is:

1. In a crosshead, a pair of beams, means securing said beams in horizontal spaced relationship, a pair of roller blocks movable between said beams, a rod carried by each of said blocks and projecting laterally therefrom, chain attachments carried by the outer ends of said rods, said beams having vertically aligned holes therein, and a polished-rod swivel carried by one of said beams circumscribing the hole therein, comprising a collar and a bearing member having an arcuate undersurface, both said collar and bearing member being of a diameter greater than the hole in the beam by which the swivel is carried for the swivelled support of a polished rod extending through the holes in said beams.

2. In a crosshead for supporting a rod string comprising a plurality of rod sections connected serially together by couplings, a pair of beams, means securing said beams in horizontal spaced relationship, a pair of roller blocks movable between said beams, a rod carried by each of said blocks and projecting laterally therefrom, chain attachments carried by the outer ends of said rods, said beams having vertically-aligned holes therein of a diameter greater than that of the couplings of the rod string, a clamp above said beams to receive and engage a rod string extending through said holes, and a swivel carried by one of said beams circumscribing the hole therein, comprising a supporting member and a superposed bearing member interposed between said last-named beam and said clamp to encircle the rod string, opposed faces of said supporting member and bearing member being complementarily concave and convex, respectively, to tiltably swivel said clamp and rod string on said lastnamed beam.

3. In a crosshead for supporting a rod string comprising a plurality of rod sections connected serially together by couplings, a pair of beams, means securing said beams in horizontal spaced relationship, a pair of roller blocks movable between said beams, a rod carried by each of said blocks and projecting laterally therefrom, chain attachments carried by the outer ends of said rods, said beams having vertically-aligned holes therein of a diameter greater than that of the couplings of the rod string, a clamp above said beams to receive and engage a rod string extending through said holes, and a swivel carried by said last-named beam and interposed between the latter and said clamp comprising a concave bearing member of a diameter greater than the hole in the beam by which said swivel is carried for the tiltable and rotatable support of a rod string extending through the holes in said beams.

LUTHER A. BLACKBURN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 80,219 Randleman July 21, 1868 101,726 Graham Apr. 12, 1870 1,052,948 Owens et a1. Feb. 11, 1913 1,097,333 Kinmount May 19, 1914 1,928,114 Scheppler Sept, 26, 1933 2,050,960 Olivetti Aug. 11, 1936 2,325,874 OLeary Aug. 3, 1943 2,351,183 Blackburn June 13, 1944

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