Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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TELESCOPING LIGHTWEIGHT ANTENNA TOWER
ASSEMBLY AND THE LIKE
The present invention relates to antenna tower
assemblies or masts and the like, being particularly directed
to lightweight structures of the telescoping type, readily
raised and lowered in a portable manner.
Various types of telescoping antenna rods and mast
structures have been used in various fields to take advantage
of the portability of relatively short structures which may,
on site, be extended into relatively long or high structures.
The problem of providing a very lightweight, but structurally
strong, telescoping tower for an antenna or similar rig that
may be erected and collapsed in a portable manner has not,
however, been satisfactorily addressed in terms of each of
weight, numbers of different types of parts (and consequent
complexity and cost), simplicity of erection and lowering, and
stability, particularly for tall structures, and guy wire
requirements.
An object of the present invention is to provide a
novel telescoping antenna tower assembly and the like that in
large measure obviates the above-discussed problems and pro-
vides a lightweight, structurally sound tower or mast assembly
embodying many common or identical lightweight parts and
simple raising and lowering mechanism, enabling portability
and ease of operation.
Another object is to provide a novel aluminum or
similar telescoping mast or tower structure of more general
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utility, also.
Other and further objects are explained hereinafter
and are more particularly delineated in the appended claims.
In summary, from one of its broader aspects, the
invention embraces a lightweight telescoping antenna tower
assembly having, in combination, a plurality of coaxially
mounted hollow equilateral triangular aluminum tubular
sections enclosing successively diminishing areas, one nested
within the other(s) in parallel longitudinal relationship,
roller means disposed between the adjacent corners of the
successive tubular sections to permit sliding longitudinal
axial relative movement, pulley means mounted on the tubular
sections, and winch means disposed near the bottom of the
outer tubular section and connected with cables longitudinally
harnessed over the pulley means to permit raising and lowering
of the tubular sections by the cable in order to erect and
lower the tower. Best mode and preferred embodiments and
details are later presented.
The invention will now be described with reference
to the accompanying drawings Figs. lA and lB of which are side
elevational views of an antenna tower constructed in accor-
dance with the invention in collapsed or retracted position
and elevated position, respectively;
Figs. 2A and 2B are isometric views of successive
sections of the tower, upon an enlarged scale, with preferred
equilateral triangular tubular elements;
Fig. 3 is a transverse section near the bottom of
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the mast;
Fig. 4 is a fragmentary top elevation of the tele-
scoped mast of Figs. 2A and 2B, upon a larger scale; and
Fig. 5 is an isometric view, partly broken away,
illustrating an alternate cable pulley mounting arrangement.
Referring to Figs. lA and lB of the drawing, the
mast or tower structure of the invention is shown constructed
of a plurality of hollow equilateral triangular aluminum or
similar thin-walled tubular sections 1, 2, 3, 4, 5, etc.,
enclosing successively diminishing areas (for structural
rigidity), one nested within the other(s) in parallel longi-
tudinal successive coaxial relationship. To achieve light-
weight and component or part similarity or identity, portabi-
lity, and easy assembly and disassembly, the tubes are prefer-
ably formed of similar aluminum sheet sections S, Fig. 4,
bolted, swedged or otherwise edge-secured at B to similar
extruded aluminum corner brackets 5'; but the embodiment of
Figs. 2A-B, 3 and 5 are shown for illustrative purposes as
having extruded integral tubular sides.
At or near the corners or vertices of successively
adjacent tubes 1, 2, 3, 4, etc., are pairs of externally
mounted upper and lower pulley wheels P, more particularly
shown in Figs. 2A and 2B, receiving a cable harness C from a
winch W (Figs. lB and 3) preferably disposed at the bottom of
the outer tube 1 for ready hand, foot-pedal or other
operation. The cable harness is designed to enable the
tubular sections to be elevated one within the other, along
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rollers R in the corner, Figs. 3 and 5, for erection of the
tower, and also for positive cable control in lowering the
same.
A suitable cable harness arrangement is shown sche-
matically in Fig. lB, and portions in Figs. 2A and 2B.
With the mast assembly fully retracted as shown in
Fig. lA, and with winch W, Fig. lB, hand cranked by the
operator, a tension is developed within the cable of the
harness arrangement which tension, due to the low frictional
resistance of the sheaves, is the same throughout the system.
This cable tension is transmitted first from the winch drum
affixed to the side of outermost section 1 upward to and
around the sheave affixed near the upper edge of this outer-
most section. It then continues downward to and around the
sheave affixed near the lower end of the next inner section 2,
then upward to and around a sheave affixed near the upper end
of section 2. This connective means is continued through the
successively inwardly located mast sections until the cable is
finally terminated by means of a fixed connection to the lower
end of the innermost (top) mast section.
As the tension in the cable is increased, all mast
sections remain stationary until sufficient tension is deve-
loped to raise the lightest, innermost mast section 5 in Fig.
lB. This section extends upward, out of the next innermost
section 4, until it reaches the limit of its travel and
becornes locked in section 4. As the cable tension is increas-
ed and becomes sufficient to raise the combined weights of
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sections 5 and 4, this sequence is repeated, with section 4
extending upward, out of section 3; and so on.
An alternate cable harness arrangement for hoisting
is shown in Fig. 5. In this arrangement, a cable is affixed
to the upper end of one mast section 1, in Fig. 5, extends
upward to and over a sheave near the upper end of the next
inner mast section 2, and then downward, where it is affixed
to the lower end of the next inward mast section 3. When the
outer mast section 1 is fixed and the middle mast section 2 is
raised, the upward motion of the inner section will cause the
simultaneous raising of the innermost mast section 3. A hoist
cable from the winch W attached to the side of lowermost mast
section 1 extends upward to and over a sheave affixed to the
upper end of the lowermost section. This cable extends
downward to the lower end of mast section 2. When the hoist
cable is retracted by the winch, the middle section 2 is
raised relative to mast section 1, which causes mast section 3
to raise relative to mast section 2 as just described. This
cable arrangement between mast sections is repeated, making
all mast sections thus serially connected. The net result is
that all mast sections extend simultaneously upon activation
of the winch instead of extending singularly.
Winding in the winch W will thus cause successive
elevation of the tubular sections 2, 3, 4, etc., with the
uppermost section (shown as 5) internally carrying the antenna
A, which is raised above the mast section 5. The sections are
held in elevated position by the taut cable and are lowered
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by the cable, as well, to prevent slippage.
When the rotation of the winch is reversed, the
lower mast section 2, Fig. lB, will retract into section 1
under the influence of gravity, and when fully seated, mast
section 3 will retract into section 2, etc., until all
sections are nested as shown in Fig. lA. However, when the
winds are sufficiently strong, friction between the mast
sections can prevent the smooth and orderly retraction just
described. To avert the undesirable consequences resulting
from such a situation, a retraction cable 6, Fig. lB, is
provided. This consists of a cable connected from the lower
end of the uppermost section 5, extending directly downward to
a sheave in the base of lowermost section 1, and thence to a
drum on the winch W.
A satisfactory telescoping, mast or tower of this
type has been constructed with the following section
dimensions:
Length, Retracted - - - - - - - - - - - - - - - - - -70 IN.
Length, Fully Extended ---(NOT INCL. ANTENNA--23 Ft.) 6 IN.
Width, Triangular, each side dimension - - - - - - -7.8 IN.
Total Weight, Operating - - - - - - - - - - - - - - 40 LBS.
Total Weight, Transport - - - - - - - - - - - - - - 46 LBS.
Max. Cable Tension~ To Extend - - - - - - - - - - - 44 LBS.
Max. Guy Tension, 90 M.F.R. Wind,
Upper Guy - - - - - - - - - - - - - - -300 LBS.
Lower Guy - - - - - - - - - - - - - - - -120 LBS.
For lightweight construction, the sheet walls of the
triangular tubular members may be apertured as by punched
holes H, the inner punching of which adds structural rein-
forcement, or by other perforations or lattice structues.
If desired, the inner tubular sections may initially
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be raised together before telescopically raising the
successive inner tubes to successively higher elevation, and
further modifications will also occur to those skilled in this
art, and such being considered to fall within the spirit and
scope of the invention as defined in the appended claims.
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