Folding tower

May 2, 1961

R. E. FISHER

2,982,379

FOLDING TOWER

Filed June 23, 1958

Sheets-Sheet 1

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ATTORNEYS

May 2, 1961

2,982,379

R. E. FISHER

FOLDING TOWER

Filed June 23, 1958

Sheets-Sheet 2

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ATTORNEY'S

May 2, 1961

2,982,379

R. E. FISHER

FOLDING TOWER

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May 2, 1961 r. _E fisher 2,982,379

FOLDING TOWER

Filed June 23, 1958 4 Sheets-Sheet 4

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INVENTOR.

ROBERT EF/SHER

BY

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ATTORNEYS

United States Patent Office

2,982,379

Patented May 2, 1961 γ 1

2,982,379

FOLDING TOWER

Robert E. Fisher, Berkeley, Calif., assignor to Up-Right, Inc., Berkeley, Calif., a corporation of California

Filed June 23, 1958, Ser. No. 743,897

Claims. (CI. 189—19)

This invention relates to folding towers and, more particularly, to folding tower sections which may be un| folded and erected to form a tower of a desired height.

It is a principal object of the invention to provide a tower section having no loose parts, which may be easily :. erected by hand into a rigid tower section for assemblage into a tower structure, and which may be easily disassembled and folded into a compact storage unit.

Another object is to provide a folding tower structure with improved locking devices for locking the tower section in its erected position to prevent accidental collapse of the tower.

A further object of the invention is to provide a folding tower section which is light in weight, rigid when erected, easy to repair and service, with minimum wind resistance, and economical in manufacture.

A more specific object of the invention is to provide a folding tower 'section comprising a pair of generally vertical parallel legs, a generally horizontal cross beam connected between said legs, said cross beam'comprising first and second members each pivotally connected at one end thereof to one of said legs, a link pivotally connected at each end thereof to the other ends of said members, and a locking sleeve surrounding said cross beam for longitudinal sliding movement thereon, said locking sleeve having a length greater than the distance between the pivotal connections of said link.

Another specific object is to provide a folding tower section comprising a plurality of. generally vertical pari allel legs, a plurality of generally horizontal cross beams ¹ connected between adjacent of said legs, each of said cross beams comprising first and second elongated members each pivotally connected at one end thereof to one of ¹ said legs, a link pivotally connected at each end thereof to the other ends of said elongated members, a locking sleeve loosely surrounding each of said cross beams for longitudinal sliding movement thereon, and means for holding said cross beams in compression when said locking sleeve surrounds said links and the other ends of said elongated members, whereby said links will be tilted within said sleeves.

Other objects and advantages will become apparent in the course of the following detailed description.

Referring now to the drawings forming a part of this application, and in which like parts are designated by . like reference numerals throughout the same,

Fig. 1 is a perspective view of a tower section constructed in accordance with the invention.

Fig. 2 is an exploded perspective view of the invention, illustrating the manner in which the sections may be telescopically connected and leveled.

. Fig. 3 is a perspective detail view of one of the cross beams shown in extended position.

Fig. 4 is a perspective view, illustrating the folded storage position of a tower section.

. Fig. 5 is a sectional view of a cross beam and locking sleeve, illustrating the effect of gravity in restraining unlocking movement of the locking sleeve.

Fig. 6 is a view similar to Fig. 5, illustrating the effect of compression on the cross beam in restraining unlocking movement of the locking sleeve.

Fig. 7 is a view similar to Fig. 5, illustrating a modifi5 cation of the invention.

Referring now to the drawings, and in particular to Fig. 1, a tower section, generally indicated by the reference numeral TO, comprises a plurality of generally vertical and parallel tubular legs 11. Tubular cross beams 10 12 extend generally horizontally between adjacent of the legs 11. A platform 13 seats upon the upper-set of cross beams and is secured thereto by any conventional manner. The platform 13 is provided with a central access opening 14, and a ladder 15 is hooked thereto to extend IS downwardly to the platform of the next lower tower section (not shown) , as is conventional in towers of this type. Diagonally disposed guy wires 16 extend between adjacent legs 11 for bracing purposes, as will be explained more fully hereinafter.

Fig. 2 illustrates a half length tower section 10', in which the legs 11' are approximately one half the length of the legs 11 shown in Fig. 1, for utilization in instances where the full height of the tower section 10 is not desired. In all other respects, the construction of tower 2® sections 10 and 100' is identical. The lower ends of the legs 11' are reduced in diameter at 17 in order to fit telescopically into the tubular corner members 18 of the base frame 20, which latter members in turn telescope onto the leveling screws 21 to rest upon the upper wing ³⁰ nuts 22. As is apparent, the wing nuts 22 may be moved upwardly or downwardly relative to the base plates 23, as desired, and the lower wing nuts 24 may be employed as lock nuts to hold the upper nuts against accidental displacement.

The upper ends of the legs 11' are open, in order to receive the reduced lower ends 17 of the next highest tower section telescopically thereinto. When so assembled, the sections may be locked together by cotter: ₄₀ pins or the like, which may be inserted into the register- : ^υ ing holes 26 and 27 formed in the upper and lower ends, respectively, of the legs.

Referring now to Fig. 3, each cross beam 12 comprises two elongated tubular members 31 and 32, preferably of equal length, each of which is pivotally con45 nected at one end by bolts 33 to an L-shaped bracket 34 mounted on adjacent legs 11. The brackets 34 are permanently and rigidly connected to the legs by welding, soldering, riveting, or any other conventional manner. Links 35 are pivotally connected at either end 50 thereof by bolts 36 to the other ends of the members 31 and 32.

An elongated locking sleeve 37 is mounted on tubular member 32 for free longitudinal and rotative movement thereon, and has a relatively loose fit thereon. A bayonet 55 locking slot 38, formed in one end of the sleeve, cooperates with an outwardly projecting stud 39 on tubular member 31 to lock the sleeve against longitudinal movement when in locking position. As is apparent, the locking sleeve is considerably longer than the distance 60 between the bolts 36 so that, when locked (dotted-line position of Fig. 3), the sleeve 37 will surround the links 35 and portions of both of the tubular members 31 and 32.

The diagonal guy wires 16 have an eye clevis 41 formed on both ends thereof for permanent attachment to the L-shaped bracket bolts 33.

When in storage and transportation, each tower section is fully collapsed, as shown in Fig. 4, with the legs ₇₀ 11 and cross beam members 31 and 32 all parallel with one another. As is apparent, the distance between the bolts 36 must be slightly greater than the diameter of the

2,982,379 tubular members so that these members will be parallel when collapsed.

To erect a tower section, the legs 11 are pulled apart by hand, causing the cross beam members 31 and 32 to unfold generally to the position shown in Fig. 3. The guy wires 16 are manufactured in proper lengths so that all slack will be taken up when the cross beam members 31 and 32 are both generally horizontal but yet are substantially out of co-axial alignment, such mis-alignment being allowed by the toggle action of the links 35. The locking sleeves are then forced to the dotted-line position of Fig. 3, with such movement causing the cross beam members 31 and 32 to come into substantial alignment to, in turn, impart a tension in the guy wires. The locking sleeve is then manipulated to lock the bayonet slot 38 onto the stud 39. In like manner, all of the other cross beams 12 are locked into place, thus forming a rigid tower section unit with tension applied to all of the guy wires and with all cross beams 12 held in compression thereby. The lower ends 17 of the legs 11 are then inserted into the base frame and the tower section is leveled. The next tower section is then erected in the same manner, is inserted into the upper ends of the legs of the previously erected section and is locked thereto by cotter pins or the like extending through the registering leg holes 26 and 27. The platform sections 13 and ladders 15 are installed in a customary manner as the tower is erected. At desired intervals, guy wires are connected to the tower to extend down to the ground.

The tower is dismantled in the reverse order, and is folded up, as in Fig. 4, for storage or transportation.

Fig. 5 illustrates one manner in which the locking sleeve is restrained from movement from its locking position. The weight of the tubular members 31 and 32 will cause the cross beam 12 to pivot slightly about the L-shaped bracket bolts 34 and sag in the middle. This causes a gravity force, identified as Fg, to be imposed upon the central lower inside surface of the locking sleeve 37, and also produces corresponding reaction forces, identified as Fr, to be imposed upon the inside end edges of the locking sleeve. The combination of these forces produces friction forces to restrain the locking sleeve from rotating and moving longitudinally in order to prevent accidental unlocking of the cross beam 12.

Fig. 6 illustrates another manner in which the locking sleeve is restrained from unlocking movement. As has been described above, when locked, the cross beams 12 will be under compression, as indicated by the compressive forces Fc, as a result of the tensions in the guy wires 16. Since the pivoted link 35 makes the cross beam 12 unstable in compression, the link will be slightly cocked from a horizontal position, and the tubular member 31 will bear downwardly against· the inside of the locking sleeve, as indicated at Fo, and the tubular member 32 will similarly bear upwardly against the inside of the locking sleeve, also indicated as Fo. The friction between the locking sleeve and the tubular members 31 and 32, as a result of the offset forces Fo, will thus restrain rotation and longitudinal movement between the sleeve and cross beam. The amount of the offset forces varies with amount of horizontal offset between the pivot bolts 36, which is equal to the difference between the outside diameter of the cross beam members 31 or 32 and the inside diameter of the locking sleeve 37. This amount of offset may be increased by forming the holes in members 31 and 32 for bolts 36 at points offset from the longitudinal axes of the members 31 and 32, as shown in Fig. 6. Then, the total offset is the initial vertical distance between the pivot bolts 36 plus the differences in diameter between the members 31 or 32 and the locking sleeve, and the offset forces restraining unlocking of the sleeve will be increased.

Fig. 7 illustrates a modification of the invention and illustrates how the locking sleeve 37' may be positively locked by the compression of the cross beam 12. In this instance, a generally rectangular link 35' is provided, which has opposed corners 42 and 43 thereon. When the cross beam 12 is placed under compression as the locking sleeve is moved to locking position, the link 35' will be tilted, as above described. When the openings 44 in the sleeve are moved adjacent the link corners 42 and 43, these corners will be forced outwardly through these openings, and will lock the sleeve 37' against rotation and longitudinal movement. This particular feature may be employed with or without the bayonet connections 38 and 39, as desired, and the bolts 36 may be in alignment with the axes of the cross beam members 31 and 32, or out of alignment therewith as desired, it being obvious that the locking force will be considerably increased if the latter condition is present, as discussed above in connection with Fig. 6.

The tower section units are preferably made of aluminum alloys, so as to combine the best properties of strength and lightness, although it is apparent that other materials may be used, if desired.

The above described tower has various advantages that are set forth below. Each tower section folds into a compact storage unit, will all legs and cross beam members parallel, because of the link construction. If only a single hinge were provided in the center of the cross beams, the cross beam members could not fold parallel to one another.

There are no loose parts in each tower section, so that when stored or transported, there is no danger of losing any of the elements. All of the guy wires 16 are permanently attached to the section, and fold up inside the folded up section.

The weight of the tower is kept to a minimum by providing guy wires for bracing and by using tubular members for the legs and cross beams.

The erected tower has a minimum wind resistance, due to the fact that the guy wires 16 have practically no wind resistance, and that the round tubes 11 -and 12 have much less wind resistance than other conventional structural shapes such as angles, channels and plates.

The tower is quick and easy to erect and disassemble, and requires no tools for the task.

The tower is easy to repair or to replace parts because all of the legs are identical. All cross beams are identical. All guy wires are identical. All hinge bolts are identical.

Since all faces of the tower are identical, accessories, such as antennae, hoisting davits, outboard platform structures and the like can be attached to any face of any section in like manner.

Although the tower has been illustrated as being square in cross section, it is to be realized that a tower can be similarly constructed with three legs, or more than four legs. Also, a rectangular tower could be so constructed and could serve either as a tower or scaffold.

Thus it is to be realized that the particular forms of the invention herewith shown and described are to be taken as preferred embodiments 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 attached claims.