US3511388A - Pin connection for elongate load supporting boom structure - Google Patents

Description

May 12, 1970 D.

PIN CONNECTION FOR ELONGA'IE LOAD SUPPORTING BOOM STRUCTURE -c. MARKWARDT 3,511,388

2 sheec s sheet 1 Filed Sept. 18, 1967 INVENTOR DON C. MARKWA'RDT 'FIG. 2

May 12, 1970 1:2. c. MARKWARDT PIN CONNECTION FOR ELONGATE LOAD SUPPORTING BOOM STRUCTURE 2 Sheets- Sheet 2 Filed Sept. 18, 19a? INVENTOR DON C. MARKWARDT United States Patent 3,511,388 PIN CONNECTION FOR ELONGATE LOAD SUPPORTING BOOM STRUCTURE Donald C. Markwardt, Manitowoc, Wis., assignor to The Manitowoc Company, Inc., Manitowoc, Wis., a corporation of Wisconsin Filed Sept. 18, 1967, Ser. No. 668,482 Int. Cl. B66c 23/70, 23/06 U.S. Cl. 212-144 12 Claims ABSTRACT OF THE DISCLOSURE The instant invention comprises a pin connection for boom segments in which the centerlines of the terminal lacing elements intersect within the confines of the chords thereby achieving the desiderata of easy assembly and disassembly of the boom segments, avoidance of localized eccentric loading of the chord, and general predictability of force diagrams drawn at the junction of the terminal lacing element and the chord. This is effected by recessing a female connector socket within the terminal end portion of the chord and securing the terminal lacing element This invention relates to a pin connection for elongate load supporting boom structures, and more particularly to a connection for crane boom structures, and the like, that is relatively easy to assemble and disassemble and at the same time produces an optimum distribution of forces along the boom structure.

Load supporting boom structures of the type used in equipment, such as cranes, draglines, and the like, are generally pivotally mounted adjacent one end portion thereof to a stationary or mobile base support and are equipped With suitable rigging to alter the inclination of the boom structure with respect to the ground in order to perform the various functions for which the equipment is made. The trend of recent years is to provide longer and longer boom structures in order to meet the requirements and demands of construction and excavation problems.

In order to allow dismantling of the boom structurefor convenient transportation from place to place, boom structures may be constructed in a plurality of disconnectible segments. Boom segments are conventionally made of a plurality of generally axially disposed or extending parallel chords interconnected by diagonally disposed or extending lacing elements to provide the desired structural strength. The terminal end portions of each chord is generally provided with connections of one type or another in order to secure abutting boom segments together.

One desideratum of boom segment construction is that the centerlines of the lacing elements intersect generally at the centerline of the chords to avoid localized eccentric loading of the chord and to provide predictable force diagrams at the junction of the lacing element and the respective chord of the boom structure. This has not been difiicult to achieve intermediate the ends of the chords. However, difficulty has arisen in constructing the boom segments such that the terminal lacing elements of abutting boom segments intersect within the confines of the respective chord as near as possible to the centerline of the chord.

One manner of achieving the desired result is by using flanged connections between abutting boom segments. This has proven undesirable because of the multiplicity of flange nuts that must be removed upon disassembly and reinstalled upon assembly of abutting boom segments thereby unnecessarily prolonging break down and set up time when a crane is moved from one construction site to another.

It is an object of the instant invention to provide a readily assemblable and disassemblable boom structure for cranes and the like wherein the connection between adjacent boom segments enables the centerlines of the terminal lacing elements to intersect within the confines of the chord.

Another object of the instant invention is to provide a pin connection for a disassemblable load supporting boom structure that allows the centerlines of terminal lacing elements of the several boom segments to intersect within the confines of the chords.

Still another object of the instant invention is to provide a pin connection for load supporting boom structures in which a female socket is disposedwithin the end portion of one of the chords to allow placement of the terminal lacing element in a most desirable position.

A further object of the instant invention is to provide a male-female connection for boom structures and the like in which peripheral abutting faces of the connection provide additional bearing surface to resist relative angular movement between boom segments.

-A still further object of the instant invention is to provide a boom connection having the characteristics described wherein a single pin may be used to connect abutting chords.

Still another object of the instant invention is to provide a pinned boom connection which may be readily constructed to provide rapid assembly and disassembly consistent with optimum distribution of forces at the junction of adjacent boom segments.

Other objects and important features of the invention will be apparent from a study of the specification following taken with the drawing, which together show, illustrate, describe and disclose a preferred embodiment or modification of the invention and what is now considered to be the best mode of practicing the principles thereof. Other embodiments or modifications may be suggested to those having the benefit of the teachings herein, and such other modifications or embodiment are intended to be reserved especiallyas they fall within the scope and spirit of the subjoined claims.

In the drawing:

FIG. 1 is a side elevational view of a typical type of crane apparatus equipped with load supporting boom structure constructed in accordance with the principles of the instant invention;

FIG. 2 is an enlarged partial side elevational view of the load supporting boom structure of FIG. 1 and con- 3 stitutes an enlargement of the structure at the junction as shown within the dotted circle of FIG. 1;

FIG. 3 is a further enlarged side elevational view of the junction between abutting boom chords with certain parts thereof being cut away for purposes of illustration;

FIG. 4 is a longitudinal cross-sectional view of the pin connection of the instant invention taken substantially along line 44 of FIG. 3 as viewed in the direction indicated by the arrows, and

FIG. 5 is a transverse cross-sectional view of the pin connection of the instant invention taken substantially along line 55 of FIG. 3 as viewed in the direction of the arrows.

Attention is now directed to FIG. 1 of the drawing wherein there is shown, for the purpose of illustration only, a crane having elongate load supporting boom structure 12 hingeably connected to an upper works 14 by a hinge structure 16. In accordance with conventional practice, the upper works 14 is mounted by a roller assembly 18 on a lower works 20 illustrated as being of the endless track variety to provide mobility along ground surface 22.

The upper works 14 carries a boom rigging assembly 24 as well as a counterweight 26. A suitable load line or hoist cable 28 is wound about a hoist drum (not shown) in-the upper works 14 and passes through a plurality of guides 30 along the boom structure 12 to sheaves 32 secured adjacent a boom point 34. The load hoist cable 28 then passes on to any load L being handled by the crane 10.

The boom structure 12 is comprised of a plurality of generally similar intermediate segments 36, a boom butt segment 38 hinged to the upper works 14, and a boom top segment 40, all of which are secured in axial relationship relative to each other by pin connecting means to be described and disclosed in more detail hereinafter.

Although the following description will be in terms of the intermediate boom segments 36, it should be understood that the connection of the boom butt and boom top segments 38 and 40 at each end of the boom structure 12 may be effected in the same manner.

Each of the boom segments 36 comprises a plurality of chords 42 which are illustrated as being disposed at the corners of an imaginary rectangle although it should be understood that any configuration will suffice. For purposes of description only, each of the chords 42 may be divided into an intermediate chord section 44 of any desired cross-sectional configuration, a first terminal chord section 46 and a second terminal chord section 48.

Interconnecting adjacent chords 42 of each of the boom segments 36 are a plurality of diagonal intermediate lacing elements 50 each of which converges with respect to the lacing element 50 immediately adjacent thereto so that a centerline 52 of each of the intermediate lacing elements 50 intersects with the centerline of the adjacent lacing element within the confines of the respective chord 42 and preferably intersect on a centerline 54 of the chords 42. A pair of transverse lacing elements 56 may be disposed at each end portion of the boom segments to interconnect the diagonally opposed chords together to enhance torsional and bending stability. Similarly, additional transverse lacing elements may be disposed intermediate the end portions of each boom segment for similar purposes.

As shown in FIGS. 2 and 3 one terminal end portion of each boom segment 36 includes a first terminal lacing element 58 connected at one end portion thereof to the intermediate chord section 44 so that a centerline 60 intersects the centerline 52 of the adjacent intermediate lacing element 50 on the centerline 54 of the chord 42. The other end portion of the first terminal lacing element 58 is fixedly secured, as by welding or the like, to the first terminal section 46 of the chord 42. The other end portion of the boom segment 36 is provided with a second terminal lacing element 62 secured at o e n portion thereof to the intermediate chord section 44 so that a centerline 64 intersects the centerline 52 of the adjacent intermediate lacing element 50 on the centerline 54 of chord 42. The other end portion of the second terminal lacing element 62 is connected to the second terminal section 48 of the chord 42 so that the centerline 64 intersects the centerline 60 of the first terminal lacing element 58 within the confines of the chord 42 and preferably as near as possible to the centerline 54 thereof. As may be clearly seen in FIG. 3, the centerlines 60, 64 of the first and second terminal lacing elements 58, 62 intersect in such a manner as to fulfill the desiderata of avoiding eccentric loading of chords 42 as well as providing generally predictable force distributions at the junction of the abutting boom segments 36.

Referring now to FIGS. 3-5, the pin connecting means of the instant invention is illustrated as including a female connector socket formed within the first terminal chord section 46, a male connector formed by the second terminal chord section 48 and a pin 66 securing the male and the female connectors together. The female socket formed by the first terminal chord section 46 comprises a body portion 68 of generally identical external crosssectional configuration to the intermediate chord section 44. The body portion 68 has one end portion 70 of reduced external dimension received in the open end portion of the intermediate chord section 44 with suitable weld material 72 securing the body portion 68 to the intermediate section 44. A recess 74 may be formed in the terminus of the end portion 70 to reduce the weight of the body portion 68 consistent with desired strength.

Centrally of the body portion 68 and coaxial with the centerline 54 is a blind cavity 76 having an enlarged outer end portion forming a shoulder 78 and a face 80. A transverse pin receiving opening 82 communicates with the cavity 76 to receive the pin 66 thereby providing means for retaining the male connector in the female socket formed with the end portion of the chord 42.

The second terminal section 48 of the chord 42 comprises a body portion 84 having one end portion 86 of reduced external dimension received in the open end portion of the intermediate chord section 44 and retained therein by suitable weld material 88 or other connecting means. An enlarged recess 90 and a smaller dimple 91 formed in the end portion of the body portion 84 are provided to minimize weight consistent with needed strength and to allow uniform cooling of the material after casting. Immediately beyond the area where the second terminal lacing 62 is secured to the body portion 84 the external dimension of the body portion 84 is reduced to form a face 92 in abutting relation to the face 80 of the female connector socket to carry compressive loads from one chord to the other and to provide additional bearing area to withstand any tendency toward relative angular movement between adjacent boom segments.

Similarly a radially facing shoulder 94 is preferably closely received by the open end portion of the blind cavity 76. A tongue 96 of the body portion 84 extends into the cavity 76 and provides a pin receiving aperture 98 aligned with the aperture 82 of the female socket.

The pin 66 is of conventional construction and comprises a first tapered end portion 100 having a transverse opening 102 therethrough to receive a cotter key 104 or other temporary retaining means. The other end portion 106 of pin 66 is tapered throughout a greater length and at a lesser angle than end portion 102 and also provides a transverse opening 108 receiving a cotter key 110 or the like.

It will be noted from FIG. 2 that the end portion of pin 66 is visible in the chord nearest the bottom of the figure but is not visible in the chord illustrated thereabove. The disposition of the pins 66 at 90 relative to each other is to provide for movement of the pin 66 out of the apertures 86, 98 without interference from the terminal lacing ele rfnents' 58; For example, if the pin 66in FIG. 3 were disposed at 90 with respect to'the actually illustrated pin, interference between the pin "66 and the terminal lacing element 58 would result. 7

As a matter of convenience of manufacture, the terminal chord sections 46, 48 are cast of material having the desired structural characteristics. Because the casting operation does not produce articles havingclose tolerances, the faces 80, 92 are machined to provide the close abutting relation needed.

It will be readily apparent that the adjacent boom segments 36 are disassembled by removing the pins 66 as by the use of a punch and hammer thereby tending to make assembly and disassembly a relatively easy and rapid operation. It will also be noted that the compressive loads transmitted to the junction of adjacent boom segments 36 is carried by the abuttifig faces 80, 92 while tensile loads are transmitted by the pin 66.

While the invention has been described and disclosed in terms of an embodiment which it has assumed in practice, the scope of the invention should not be deemed to be limited by the precise embodiment herein shown, illustrated, described and disclosed and it is to be understood that other such embodiments are intended to be reserved.

I claim as my invention:

1. An elongate load supporting structure comprising:

a plurality of abutting generally coaxial segments having at least three chords; intermediate diagonal converging lacing elements disposed intermediate the end portions of the chords interconnecting adjacent chords together with the centerlines of adjacent intermediate lacing elements intersecting within the confines of the chords; and at least one terminal diagonal lacing element for each chord disposed on one end portion of each segment interconnecting adjacent chords together and having a centerline intersecting the centerline of the adjacent intermediate lacing element within the confines of one of the adjacent chords and intersecting the other-of the adjacent chords at the terminal end portion thereof; and means connecting abutting segments together and disposing the intersection of the centerlines of the adjacent terminal lacing elements of abutting chords within the confines of the chord, the connecting means comprising a male connector disposed on selected end portions of the chords and having an apertured tongue extending beyond the terminalend portion of the chord; means forming a female connector socket within the adjacent terminal end portion of an abutting chord for receiving the tongue and having an aperture aligned with the tongue aperture; and a removable pin received in the aligned apertures of the male and female connectors for securing the abutting segments together. i

2. The elongate load supporting structure of claim 1 wherein the centerlines of adjacent intermediate lacing elements intersect at the centerline of the chord.

3. The elongate load supporting structure of claim 1 wherein the centerlines of adjacent terminal lacing elements intersect within the confines of the male connector.

4. The elongate load supporting structure of claim 1 wherein the male and female connectors provide abutting substantially peripheral faces for transmitting compressive loads.

5. The elongate load supporting structure of claim 1 wherein the pin resides at a point spaced from a plane drawn through the intersection of the male and female con. nectors in a direction axially along the chord which carries the female connector.

6. The elongate load supporting structure of claim 1 wherein the included angle between the terminal lacing elements and the chords is substantially the same as the included angle between the'intermediate lacing elements and the chords.

7. The elongate load supporting structure of claim 1 wherein each segment includes four chords; and further comprising a pair of transverse lacing elements on each segment interconnecting diagonally opposed chords, the transverse lacing elements being disposed immediately adjacent the terminal end portions of the chords and perpendicular to the plane of the terminal lacing elements.

8. An elongate load supporting structure comprising a plurality of abutting generally coaxial segments having at least three chords each of which has an intermediate section and two terminal sections;

intermediate diagonal converging lacing elements for interconnecting intermediate sections of adjacent chords of each segment together with the centerlines of adjacent intermediate lacing elements intersecting within the confines of the chords of the segment;

a first terminal diagonal lacing element interconnecting a first terminal section of one of the adjacent chords of a first boom segment and the intermediate section of another of the adjacent chords of the first segment with the first terminal lacing element centerline intersecting the centerline of the adjacent intermediate lacing element Within the confines of the other adjacent chord and the first terminal lacing element intersecting the first terminal section adjacent the end portion thereof;

a second terminal diagonal lacing element interconnecting a second terminal section of one of the adjacent chords of a second boom segment and the intermediate section of another of the adjacent chords of the second segment with the second terminal lacing element centerline intersecting the centerline of the adjacent intermediate lacing element within the confine of the other adjacent chord and the second terminal lacing element intersecting the second terminal section at the end thereof with the centerlines of the first and the second terminal lacing elements intersecting within the confines of the one adjacent chords of the first and the second boom segments; the first terminal section forming an apertured female connector socket within the confines of the one adjacent chord of the first boom segment; an apertured tongue secured to the second terminal section and extending beyond the end portion of the one adjacent chord of the second boom segment into registry with the female connector socket; and removable means extending through the apertures of the tongue and the socket for retaining the first and the second boom segments together. 9. The elongate load supporting structure of claim 8 wherein the centerlines of adjacent intermediate lacing elements intersect at the centerline of the chord. 10. The elongate load supporting structure of claim 8 wherein the centerlines of the first and the second terminal lacing elements intersect within the confines of the male connector. 11. The elongate load supporting structure of claim 8 wherein the first terminal section forms a peripheral face about the female connector socket; and the second terminal section forms a peripheral face at the junction of the tongue in abutting relation to the peripheral face of the first terminal section. 12. The elongate load supporting structure of claim 8 further comprising a boom butt segment secured to one of the boom segments; a boom top segment secured to another of the boom segments; an upper works; and

7 8 means hingedly mounting the boom butt segment on 3,064,503 11/1962 Fry 287-103 the upper works for pivotal movement in a generally 1,676,161 7/ 1928 Schiller 187-95 vertical plane. 1,859,894 5/ 1932 Schiller 18795 References Cited FOREIGN PATENTS UNITED STATES PATENTS 966,981 8/1964 Great Britain.

1,837,341 12/1931 Shaffer 287-l03 HARVEY C. HORNSBY, Primary Examiner, 2,545,913 3/1951 Bock 287103 2,587,838 3/1952 Green 287-2 3,011,586 12/1961 Harvey 52637 10 52 117; 212 59;2s7 1o3

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