US3009546A - Self-erecting tower structure - Google Patents

Description

Nov. 21, 1961 E. ANDERSON, sR.. ETAL 3,009,546

SELF-ERECTING TOWER STRUCTURE Filed June 10, 1960 3 Sheets-Sheet 2 'w INVENTORS AZOYO E. ANOERS MSR. BY JJ/VF/A-ZD .Q. C4PRO/V Stes This invention relates to a self-erecting tower structure for use as a scaffold, as the mast of a crane, etc. More particularly, the invention relates to a self-erecting tower structure consisting of a plurality of rigid sections that are adapted to be superimposed in end to end abutting relation in their erected positions and to be folded in superimposed parallel relation in their col-lapsed positions.

It is among the Objects of this invention to provide a tower structure of the type referred to in the preceding paragraph, in which a plurality of rigid sections may be raised from a folded horizontal position to an upright position by the application of a single force at a single point, in which the structure, when erected, can be locked in its erected position, and in which the structure is inexpensive to manufacture, simple to assemble, and easy to use.

Other objects of the invention will be apparent from the following description of a preferred embodiment in connection with the attached drawings, in which:

FIG. 1 is a diagrammatic representation of the tower structure in its folded position;

FIG. 2 is a similar representation of the structure in its partly raised position;

FIG. 3 is a similar representation of the structure in its fully erected position;

FIG. 4 is a side elevation of the tower structure in its fully erected position;

FIG. 5 is a front elevation of the structure shown in FIG. 4;

FIG. 6 is an enlarged side elevation of a portion of the tower structure shown in FIGS. 4 and 5, illustrating details of the hinged joint, the sector member, and the locking means between two adjacent tower sections;

ISIG. 7 is a section along the lines VII-VII of FIG. 6; an

FIG. 8 is a side elevation showing an eccentrically mounted sector member at the junction of two tower sections.

In accordance with this invention, the tower structure comprises a plurality of rigid sections, preferably at least three sections, that are hinged end to end. In their collapsed positions, they are folded back and forth in hori- Zontal superimposed relation. The first or lowermost section is hingedly connected to a base, and means are provided for rotating this section relative to the base from a horizontal to a vertical position. Each of the second and subsequent sections has rigidly mounted on its lower end a grooved sector member, such as a sheave or portion of a sheave, which may have, but does not necessarily need to have, its center lying on the axis of the hinge connection between that section and the downwardly adjacent section. A first flexible line extends around the first sector member at the bottom of the second section and has one end secured to that member and the other end secured to an anchor point on the base. A second flexible line passes around the second sector member attached to the bottom of the third section and has one end secured to that member and the other end secured to an anchor point on the first section. The anchor points are so selected that, as the first section is turned on its hinged connection with the base, th first flexible line exerts a turning force through the first sector member on the second section, causing it to rotate relative to the first section and in the opposie direction which causes the second flexible line to rotate the third section in the same direction as the first section.

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When the flexible lines are initially tight, the second and third sections move in unison with the first section; and, when the latter reaches it erected vertical position, all of the sections are upright and in end to end vertical align-- ment.

Referring to the diagrammatic drawings (FIGS. l3). the component parts of the tower structure are mounted on a base 1, which can be a platform on the ground or on a vehicle. A stub section or post 2 is rigidly secured to the base and extends upwardly therefrom. Rotatably mounted on a bearing m mber 3 and a shaft 4- at the upper end of the stub section is a sector member in the form of a sheave 6, having its axis of rotation to one side of the stub section and even with the top of that section. A first tower section 7 is rigidly attached to sheave 6, so that in its folded position (FIG. 1) the section extends at an angle of to the stub section and is attached to the sheave above its axis. Accordingly, when the sheave is turned 90 (in a clockwise direction in FIG. 1), the upper end 8 of stub section 2 will meet the lower end 9 of the first section in abutting relationship (see FIG. 3). Similar hinged joints are provided between other sections of the tower structure. A second sheave ll is rotatably mounted on a shaft 11 supported in a bearing member 12 at the outer end of the first section 7. To this sheave is rigidly secured a second section 13, lying (in its folded position) above and parallel to the first sections 7 and extending an equal distance beyond the foot 9 of that section. In like manner, sheave 14 is rotatably mounted on the opposite end of the second section 13 on a shaft 15 is a bearing member 16, and a third section 17 is rigidly secured to sheave id in parallel overlying relation to section 13. Another sheave 18 is rotatably mounted on the opposite end of section 17 on a shaft 19 in a bearing member 20 and rigidly secured to an end of a fourth section 21, which over-- lies and is parallel to the other sections. There can, of course, be more or less sections than here described.

A plurality of flexible lines, such as steel cables, interconnect the various sections. One line 30 has one end fastened to an anchor point A on the base 1 and extends part way around sheave 10 to a point B, where it is secured to the sheave. A second flexible line 31 has one end fastened to an anchor point 'C on the first section 7 and extends partly around sheave 14 to a point D, where it is secured to that sheave. A third flexible line 32 has one end fastened to an anchor point E on the second section 13 and extends partly around sheave 18 to a point F, where it is fastened to that sheave. In raising the sections from their collapsed or folded positions shown in FIG. 1 to their erected positions shown in FIG. 3, each of the sections 7, 13, 17, and 21 turns through an angle of 90 from the positions shown in FIG. 1. However, each of those sections turns through an angle of relative to adjacent movable sections. Accordingly, the points of attachment B, D, and F of the ends of the cables to sheaves 10, 14, and 18, respectively, should be at least 180 away from their initial points of tangency, as shown in FIG. 1.

In order for each of those sheaves to turn through 180 between the folded and erected positions of the sections, each of the flexible lines 30, 31, and 3-2 must unwind itself from its associated sheave by an amount equal to one-half of the sheaves circumference. In other words, the free length of each line, i.e., the length from its anchor point to its point of tangency, is increased during erection of the sections by an amount equal to one-half the circumference of the sheave around which it is wrapped. Accordingly, anchor points C and E on sections 7 and 13, respectively, are spaced from the axes of rotation of sheaves 10 and 14, respectively, by a distance equal to one-fourth of the circumference of sheaves 14 and 18, respectively, about which those lines are wrapped. When the sections are unfolded, points C and B will be displaced 180 about the axes of their adjacent sheaves,

or a distance equal to one-half the circumference of sheaves 14 and 18, respectively, i.e., by the same amounts as sheaves 14 and 18 are to be turned.

Since there is only 90 relative rotation between section 7 and stub section 2, the position of anchor point A for line 30 is determined as follows. Using the tangent point 36, where line 30 contacts sheave in FIG. 3, as a center, describes an arc XX having a radius L1 that is greater than the length of section 7 and less than the combined length of section 7 and stub section 2. Transfer this are to FIG. 1. Then using tangent point 37 in FIG. 1 as a center, describe a second arc YY having a radius L2 equal to the difference between L1 and one-half the circumference of sheave 10. The intersection of arcs XX and YY determines anchor point A.

Various means may be used to rotate the first section 7 about its pivot 4 for erecting the structure. The means shown in the drawings include a flexible line 40 that is wrapped partly around sheave 6 and has one attached to that sheave and the other end secured to a rotatable shaft 41, which is driven by a motor 42 through a gear reduction device 43.

It is a feature of this invention that when section 7 is rotated about its pivot 4, line 30 will be tightened and turn sheave 10 to tighten line 31 and turn sheave 14-, etc., so that all the other sections will be elevated in unison, as shown in FIGS. 2 and 3. In this sense, the sections are self-erecting. Each of the flexible lines 30, 31, and 32 exerts a turning force on the sheave to which it is attached, and each is actuated simultaneously by movement of section 7 alone. This unfolding continues until each section is vertical with its bottom abutting the top of the adjacent section, as shown in FIG. 3.

While the nature of the present invention and its operation are quite clear from the diagrammatic figures (FIGS. 1-3), there is shown in FIGS. 4-7 a more detailed structure embodying the same principles. The tower sections are in the form of tubular frames, each consisting of four parallel tubes 50 joined in front and back by transverse tubes 51 and on the sides by shorter transverse tubes 52. This frame can be conveniently made by welding the various tubes together. In addition, short channel sections 53 are welded to the sides of each section adjacent their lower ends, and to these channel sections are Welded the various sheaves that act as sector members.

Two sheaves are provided at the junctions of each pair of frame sections and are disposed on opposite sides of those sections. They are identical to each other, as are the flexible lines interconnecting them and the adjacent sections, and are identified in the drawings by prime numerals corresponding to those used in connection with FIGS. 1-3.

A further feature of the invention shown in FIGS. 47 is the provision of means for locking the sections together in their erected vertical positions. These locking means are in the form of flanges 56 and 57 on the tops and bottoms, respectively of adjacent sections and opposite the hinge axes of those sections. The locking flanges are adapted to meet in abutting relationship and be secured together by bolts 58 and nuts 59 by an operator climbing the erected structure using the transverse tubes 51 as the rungs of a ladder. These flanges are shown diagrammatically in FIG. 1 and serve the additional purpose of spacers between adjacent sections when the tower structure is in its folded or collapsed position.

To facilitate collapsing the tower structure, compres sion springs 60 may be used between the locking flanges 56 and 57 to break the joints of the erected sections and displace their centers of gravity sufliciently to enable gravity to fold those sections downward as the flexible line 30 is unwrapped from the shaft 41. The springs 69 are mounted in counterbores 61 around bolts 58 and have sufficient force to open the flanges several inches in the absence of tension on line 30 (see FIG. 6).

It will be apparent that sheaves 6, 10, 14, and 13 may be replaced by other grooved sector members, including sectors of the sheaves themselves. Since none of the sheaves rotates more than it is not necessary that the sector members have a full circumference. In addition, the sector members may have a different curvature than is shown in FIGS. 1 7, in which the sheaves are circular and rotate about their centers, thus providing constant moment arms to which the forces of the lines are applied. In many cases, it may be advantageous to provide a longer moment arm at the beginning of the erection cycle, when the load is greatest, than at the end of that cycle, when the load is negligible. This can be done by using sector members having a variable effective radius, i.e., a variable distance between the successive tangent points where the flexible lines leave their grooved peripheries, this radius or distance being greatest in the position shown in FIG. 1 and least in the position shown in FIG. 3. A convenient way to accomplish this is to rotate a sector member having a circular arc periphery about an eccentric axis. Such a construction is shown in FIG. 8, the solid lines of this figure representing two ad jacent sections in their folded positions and the broken lines representing those sections in their erected positions in which one of the sections has been rotated 180 relative to the other section.

Referring to FIG. 8, two tower sections 65 and 66 are hinged at O. A grooved circular disc 67 having a center 68 is welded to section 66. A flexible line 69 anchored at a point (not shown) passes partly around the disc and is fastened thereto at point H, slightly more than 180 from the tangent point P. In the folded position of the sections (shown in solid lines), the center 68 of the disc lies between the axis of the hinge O and the initial tangent point P. The force exerted by line 69 has an effective moment arm equal to the perpendicular distance from O to the straight portion of the flexible line (or that portion extended), which is approximately the distance OP. This moment arm is approximately 50 percent larger in FIG. 8 than it would be if the center 68 of the disc coincided with point 0. When section 66 is rotated 180 about point 0 to the position shown in broken lines (corresponding to its erected position), line 69 is now tangent to the disc 67 at a point Q and the effective moment arm to which the tension on line 69 is applied has been reduced to approximately the distance 0Q, which is less than it would be if the center 68 of the disc coincided with point 0. By mounting the sector members eccentrically, therefore, it is possible to obtain greater leverage when the resisting load is greatest at the beginning of the erection cycle at the cost of decreased leverage at the end of the cycle when the resisting load is least. It will be noted that with such eccentric mounting the initial tangent points of the flexible lines (when the sections are folded) will be different from the final tangent points (when the sections are erected), which may require that the anchor points of the flexible lines be determined by trial and error.

It will be understood that the sector members may have other than circular curvatures, that they may be less than 360 in effective curvature, and that they need not be connected with or form part of the hinge joint between adjacent sections. Furthermore, the sector members need not be of uniform size for the different sections. For example, sector member 18 fixed to the bottom of the uppermost section, which offers the least resistance to rotation, may be smaller than the other sector members.

The tower structure of this invention may be used for a variety of purposes. It may be provided with a working platform 70, as shown in FIGS. 1-5, or alternatively may support the boom of a derrick, etc. Where its height and the use to which it is put require it, the tower structure can be guyed or stayed to increase its stability.

According to the provisions of the patent statutes, we have explained the principle of our invention and have iilustrated and described what we now consider to represent its best embodiment. However, we desire to have it understood that, Within the scope of the appended claims, the invention may be practiced otherwise than as specifically illustrated and described.

We claim:

1. A folding tower structure comprising a base, at least three rigid sections hinged end to end and adapted to be folded back and forth in horizontal superimposed relation, a hinged connection between the first section and the base, first and second grooved sector members rigidly mounted on each of the second and third sections respectively adjacent the hinged connection between each of those sections and the downwardly adjacent section, a flexible line extending around the first sector member and having one end secured to that member and the other end secured to an anchor point on the base, a second flexible line extending around the second sector member and having one end secured to that member and the other end secured to an anchor point on the first section, and means for rotating the first section on its hinged connection with the base from a horizontal to a vertical position, whereby the flexible lines will cause the second and third sections to rotate about their hinged connections with downwardly adjacent sections until the sections are disposed in end to end vertical alignment.

2. Apparatus according to claim 1, in which the lines extend around the grooved peripheries of the sector members through an arc of at least 180.

3. Apparatus according to claim 1, in which the anchor points of the flexible lines are so selected that the sector members to which they are attached will be rotated sub stantially 180 by the lines when the first section is rotated 90 on its hinged connection with the base.

4. Apparatus according to claim 1, in which the means for rotating the first section relative to the base includes a separate grooved sector member rigidly secured to the first section adjacent its hinged connection with the base, a flexible line extending around said sector member and having one end secured thereto and the other end secured to a rotatable shaft, and means for rotating the shaft to wrap the line thereabout.

5. Apparatus according to claim 1, in which each sector member has a periphery in the form of a circular arc, the center of which lies on the axis of the adjacent hinged connection between two sections.

6. Apparatus according to claim 1, in which each sector member has a periphery in the form of a circular arc, the center of which lies between the axis of the adjacent hinged connection between two sections and the tangent point of the flexible line to that sector member when the tower structure is in its folded position.

7. Apparatus according to claim 1, in which the hinged connections between the sections are at one side of those sections so that the sections will overlie each other in their folded positions and will stand in end to end abutting relation in their erected positions.

8. Apparatus according to claim 1, in which adjacent sections are provided with flange members on the side opposite the hinged connection between those sections, said flange members being adapted to meet in abutting engagement when the sections are in their erected positions, and means for locking the flange members in abutting relationship.

9. Apparatus in accordance with claim 8, in which spring means are provided between adjacent flange members on adjacent sections, said spring means ofiering yielda'ble opposition to the abutting engagement of said flange members.

10. Apparatus according to claim 1, in which each sector member is in the form of a circular sheave with its center lying on the axis of the adjacent hinged connection between two sections and in which the anchor point of the second flexible line is spaced from the axis of the first sector member a distance that is substantially equal to one-quarter the circumference of the second sector member.

No references cited.

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