Note: Descriptions are shown in the official language in which they were submitted.
~ 2168~11
WB-9693
~T~-~OPING MAST ASSEMBLY
R~K~OUND OF THE lNv~N~ION
The present invention relates to the art of telescoping masts
and more particularly to a telescoping mast having a drive assembly
for translation of the mast sections to a fully retFacted position,
a fully extended position or any position therebetween.
The present invention is particularly applicable for use with
mobile land and sea vehicles and to provide a lighting system used
to illuminate areas under bridges or over sharp drop-offs such as
cliffs and mountain roads.
Telescoping masts are used for many applications. Generally
such telescoping masts may be adapted to fit on the roof of a
vehicle such as a military or emergency type vehicle. Such mast is
usually outfitted with a top mounted fixture such as a light or
antenna fixed at the top of the mast.
Generally, a mast to be placed on the roof of a vehicle must
be of relatively light weight, durable, compact in size, capable of
withstanding all kinds of weather and relatively maintenance free.
A common mast used for such applications is a pneumatically
actuateld telescoping mast. 'However, such a mast is subject to
damage during operation which can affect its operability. In this
respect, the mast must remain airtight for proper operation. A
hole or fracture formed in a section of the mast may allow the
escape of air and thus affect operation and prevent proper
inflation. Pneumatic masts also lack rigidity and may be subject
to damage in high winds or from impact with adjacent objects.
Further, pneumatic masts are not generally adaptable to be
partially extended in those instances where a certain desired
1 30 elevation of a light fixture or other top mounted fixture is
i desired. Additionally, pneumatic masts are `typically only
extendable in a vertical or horizontal direction. This prevents
use of such masts under bridges or over cliff sides where it would
be desirable to extend the mast at an angle to project a light away
from its mounting. One attempt to overcome the latter disadvantage
_ 2163711
WB-9693
of pneumatic masts is disclosed in commonly owned, copending
application Serial No. 286,269, filed August 5, 1994, the
disclosure of which is hereby incorporated by reference. While
overcoming the bi-directional problem, the invention disclosed in
application Serial No. 286,269 does not overcome the other
disadvantages of pneumatic masts described hereinabove.
An alternative to pneumatically actuated telescoping masts is
a tubular type of mast assembly comprising a plurality of
telescoping mast sections and a rigid drive assembly operable to
displace the mast sections to any position between a fully
retracted position and a fully extended position. Such telescoping
mast assemblies are disclosed, for example, in United States
Patents 5,102,375, 5,107,672, 5,168,679 to Featherstone and U.S.
Patents 5,139,464 and 5,203,746 to Lehnert. In the latter patents,
the drive assembly comprises a plurality of interengaging chain
members, and such chain driven masts typically require a large
number of moving parts including a plurality of sprocket and chain
arrangements, a drive mechanism or mechanisms and special
structutral arrangements to interlock the chain members. In order
to obtain positive extension and retraction, such a rigid drive
mechanism must be used to raise and lower the mast sections.
Typically, as shown in the foregoing art, it is necessary to
provide at least two sprockets or reels to store the chain while
the mast is in the retracted position and pay-out the chain to
extend the mast.~ A significant amount of space is therefore
required to store such chain due to the cross-sectional size o~
each chain link and the plurality of reels required. Additionally,
a drive unit is often required for each of the reels. Even in
those masts where the number of reels has been reduced, at least
two chains are still required. Accordingly, masts using such drive
arrangements are undesirably expensive to manufacture and to
maintain. Moreover, such mast arrangements are heavy and
cumbersome and are not readily capable of being mounted on the
rooftop of a vehicle without adding special structural support to
the rooftop.
216~711
,
Ws-9693
A further type of extension-retraction mechanism is disclosed
in United States Patent 5,056,278 to Atsukawa. The latter
discloses band-like plates having an accurate cross-sectional shape
and which pass through corresponding contoured guide slits in
support eIements in the mast sections to extend and retract the
telescoping mast sections. Atsukawa '278 requires the use of at
least two arcuate bands driven and retracted from separate reels.
Additionally, Atsukawa requires the use of guide slits formed in a
bottom plate of each of the mast sections and located within the
telescoping sections to maintain rigidity. Further, the arcuate
band plates are not effective against vertical and lateral loads
except when the unsupported length of the bands is relatively
small. Further, as mentioned above, at least two storage reels are
required, one or the storage of each band whereby Atsukawa
requires additional space for each of the storage reels. Moreover,
Atsukawa requires plural drive roll arrangements and corresponding
drive motors for operation. All of these requirements result in
the mast being uneconomical to make and operate and, due to the
number of parts, expensive to maintain.
SUMMARY OF T~E lNv~NllON
An extendable and retractable mast is provided in accordance
with the present invention which overcomes the foregoing and other
disadvantages of the prior art. More particularly, a telescoping
mast assembly and drive assembly according to the invention reduces
the space requirements for a mast relative to that of prior art
masts, reduces the overall weight for a rigid telescoping mast, and
provides the ability to use such a mast on the rooftop of a vehicle
without the prior art disadvantages of having to reinforce the
l 30 vehicle roof. More particularly in this respect, a telescoping
mast according to the invention is capable of positive extension
and retraction of the mast sections by means of a single tubular
drive member utilizing a single take up reel or drum for storing
the drive member when the mast is in a retracted position and a
single drive motor for the reel or drum. Preferably, the drive
21 6~711
WB-9693
member is exp~n~hle and collapsible and, upon extension from the
take-up reel, the drive member expands from a flattened storage
condition to a laterally expanded hollow condition giving the drive
member rigidity in both its longitudinal and lateral directions.
The present invention advantageously provides an improved
telescoping mast assembly which can extend the mast components and
thus a utility light or other electrical device on a mast at any
desired angle to horizontal and thus directly at or over a site at
which it is required. The improved drive arrangement provides a
less complex and less expensive mechanical drive arrangement than
heretofore available. In this respect, the expandable and
collapsible drive member can be reduced to a relatively flat cross-
sectional shape, against an inherent bias, and is capable of being
wound on a take-up reel in the flat cross sectional shape. In this
flat state, the drive member has a flexibility and elasticity which
enables the drive member to be wound a number of times about the
take-up reel. When unwound from the reel, the drive member's
inherent bias expands the drive member from its flat cross section
to its ~xpanded configuration which, preferably, is that of a tube
having opposed arcuate walls providing a somewhat elliptical
contour in cross-section. In this expanded state, the drive member
is rigid in both its longitudinal and lateral directions. The
rigidity allows positive extension and retraction of the sections
of a telescoping mast. The rigidity also provides a skeletal
structure within ~a hollow tubular telescoping mast to provide
additional rigidity to such a mast in order that the mast may
support larger loads at the mast tip. A mast according to the
invention also enables reducing the number of component parts
required and also enables reducing the size of the drive assembly
in contrast to link and chain or dual drive systems in that a
single reel, single exp~n~hle and collapsible drive member and a
single drive motor is all that is required to operate the mast
assembly in the extending and retracting modes.
In accordance with another aspect of the invention, the
exr~n~hle and collapsible drive member i5 preferably comprised of
` w ` 2168~11
WB-9693
a single metal sheet having two concave portions, the sheet being
folded for the two concave portions to face one another.
Preferably, the expandable and collapsible drive member is formed
from a thin metal drive member sheet having opposite longitudinal
edges parallel to a longitudinally extending centerline. Outer
flange portions are initially formed by bending the metal foil
adjacent each of the longitudinal edges. The foil is then bent
longitudinally adjacent the centerline at two bendlines equidistant
from and on opposite sides of the centerline to form two inner
flange portions. The drive member is then folded along the
centerline to abut the inner flange portions, and the inner flange
portions are fastened together. The outer flange portions are then
abutted together and joined to form a folded metal drive member
having flanges on the opposite longitudinal edges and an unfastened
area between the flanges and in which the opposed portions of the
foil between the flanges are of concave contour. A longitudinally
extending rod is placed between the concave portions, forcing the
latter to remain in a preferred elliptical cross-sectional shape.
The metral drive member sheet is then heat treated so that the
expandable and collapsible drive member inherently assumes the
elliptical shape while in a relaxed or expanded state. After heat
treating the rod is removed. When the drive member is wound onto
a cylindrical drum or take up reel it collapses against the
inherent spring bias to assume a flat cross sectional shape on the
drum. `~
In accordance with another aspect of the present invention,
the telescoping mast assembly is constructed of polygonal tube mast
sections. The polygonal tubes provide a lightweight, rigid mast,
and when in combination with the collapsible drive member, provide
an especially rigid mast structure. The mast sections include
bearing supports. The polygonal construction of the mast allows
the use of simple bearings. Thus, the mast is easier to displace
between extended and retracted positions and a smaller motor for
driving the mast may be used.
It is thus an outst~n~;ng object of the invention to provide
2168711
..
WB-9693
an improved drive assembly for actuating a telescoping mast.
It is yet another object of the invention to provide an
improved drive assembly for a telescoping mast which provides
positive extension and retraction of the mast with the use of a
single expandable and collapsible drive member.
Still another object of the invention is to provide an
improved telescoping mast assembly which is light weight and is
compact in size.
Yet another object of the invention is to provide an improved
telescoping mast assembly in which the drive member provides added
rigidity for withst~n~ing longitudinal and lateral loads while
promoting lightness in weight of the mast assembly.
Still a further object of the invention is to provide an
improved telescoping mast assembly which is less expensive to
manufacture and is easier and less expensive to maintain than
alternative telescoping mast drive assemblies.
Yet a further another object of the invention is to provide an
improved telescoping mast assembly which reduces the number of
component parts required for operation.
Still another object of the invention is to provide an
improved drive member assembly for displacing a plurality of mast
sections which is tubular and has an inherent bias for assuming an
expanded state for extension and retraction and a collapsed state
for storage.
Yet another object of the invention is to provide a method of
constructing an expandable and collapsible tubular drive member
according to the invention.
Still a further object of the invention is to provide an
improved telescoping mast assembly comprised of polygonal tube mast
sections with bearing supports which reduces -the driving face
required to extend and retract the mast.
These and other objects of the invention will become apparent
to those skilled in the art upon reading and understanding the
following detailed description of the preferred embodiment.
-6-
168711
.
WB-96~93
~ ~ .
BRIEF DES~CRl~LlON OF THE DRAWINGS
The invention may take physical form in certain parts and
arrangement of p~artsr preferred embodiments of which will be
desc-ribèd in detail herein and are illustrated in the accom~p~anying
drawings wherein: -
FIGURE 1 is an elevation view ilIustrating use of atelesc~oping mast assembly of the present invention;
FIGURE 2 i8 a plan view showing the telescoping mast assembly
mounting arrangement aæ seen along line 2-2 in FIGURE 1;
1~0 FIGURE 3 is a side elevation view of the telescoping mast o
FIGURE 2;
FIGURE 4 is a plan view, partially in section of a drive
assembly according to the invention taken along line 4-4 in FIGURE
3;
FIGURE 5 is a sectional elevation view of the drive assembly
taken along line 5-5 in FIGURE 4;
FIGURE 6 is a sectional elevation view of the drive assembly
taken along line 6-6 in FIGURE 4;
FIGURE 7 is a cross-sectional view of the telescoping mast
assembly taken along line 7-7 of FIGURE 5;
FIGURE 8 is a cross-sectional view`of the telescoping mast
assembly taken along line 8-8 of FIGURE 5;
FIGURE 9 is an exploded view showing the coupling between the
mast sections and drive member of the mast assembly;
FIGURE 10 is`~a cross-sectional view of the outer end of the
telescoping mast assembly taken along line 10-10 of FIGURE 3;
FIGURE 11 is a cross-sectional view taken along line 11-11 of
FIGURE 10; and
FIGURES. 12A-12H are pictorial views showing the sequence of
steps in making the expandable and collapsible drive member
according to the invention.
PK~ KnED ENBODIMENT
Referring to the drawings, wherein the showings are for the
purpose of illustrating preferred embodiments of the invention only
--7--
21~711
-
Ws-9693
and not for the purpose of limiting same, FIGURE 1 shows a
telescoping mast as~embly 10 mounted on the roof 11 of a
transporting vehicle 12. As shown in phantom, telescoping mast 10
is capable of being displaced from a retracted, solid line position
to an extended, broken line position and is capable of pivoting
about an axis C from a generally horizontal position to an upwardly
inclined position. Telescoping mast assembly 10 is shown with a
utility light 14 at the upper end thereof. Mast 10 thus has the
capability of providing illumination to areas under bridges or over
sharp drop-offs such as cliffs and mountain roads. It can also be
used to light the underside of an overpass or bridge. It will be
appreciated that mast 10 may be outfitted with any desired
electrical fixture, or with a multiple light configuration,
depending on customer re~uirements. Similarly, mast 10 may be
mounted on any suitable support vehicle including, for example,
emergency or military vehicles as well as watercraft for use in
search and rescue operations.
FIGURES 2 and 3 show mast assembly 10 mounted on a base plate
21, which can be permanently or removably attached to transporting
vehicle 12. Mounted on base plate 21 is a swivel plate 22. Swivel
plate 22 is generally capable of rotating through 360 in order to
place the mast in any rotational position desired. Swivel plate 22
is rotatably supported on base plate 21 by L-shaped brackets 23
welded to base plate 21. In the preferred embodiment, swivel plate
22 is manually r`otated. Mounted on swivel plate 22 are trunnion
mounts 13a and 13b with mast assembly 10 pivotably disposed
therebetween. Mast assembly 10 is pivotably mounted on trunnion
mounts 13a and 13b by means of journals 24 and 25, respectively,
which are welded to the exterior of mast section lOa and rotatably
received wi~hin openings 26a and 26b in trunnion mounts 13a and
13b, respectively. Journals 24 and 25 provide pivot axis C and, in
the preferred embodiment, axis C of the journals is six inches
above the top of base plate 21. This allows for 15 of vertical
elevation for mast 10 from the solid line to the first position
shown in phantom in FIGURE 1. It is contemplated that the
2168711
WB-9693
elevation of axis C may be eight inches such that the mast can be
elevated to 24 as shown by the second position in phantom in
FIGURE 1. While not shown, it is also contemplated that the
trunnion mounts and journals can provide for mast 10 to be elevated
to a vertical position relative to base plate 21.
Mast 10 is adapted to be pivoted from a generally horizontal
position by an air actuated piston-cylinder unit 31 pivotally
mounted to swivel plate 22 by a support 32. The piston cylinder
unit 31 includes a piston rod 33 pivotally attached to mast section
lOa by a cylinder collar 34, whereby outward displacement of the
piston rod 33 from the cylinder causes pivoting movement of mast 10
from ~he generally horizontal solid line position to the position
shown in phantom in FIGURE 3. A hydraulic, electrical or other
suitable drive may be used to cause the pivoting movement. In its
horizontal position, mast 10 rests on and is supported by a U-
! shaped storage support 35 mounted on base plate 21.
In the preferred embodiment, mast 10 is constructed of threetelescoping sections lOa, lOb and lOc of square aluminum tubing.
Howeverl, it will be appreciated that the mast sections can be of a
material other than metal or of a metal other than aluminum and
that the cross-sectional configuration can be of any one of a
number of polygonal profiles such as rectangular, triangular
diamond and the like. Tubes lOa, lOb and lOc are axially slidably
interengaged for translation between retracted and extended
positions relative to trunnion mounts 13a and 13b. As mentioned
above, tube lOa is pivotally mounted on trunnion mounts 13a and 13b
via journals 24 and 25. In the preferred embodiment, tube lOa is
2.5 inches square and 68.25 inches long. Tube lOb is slidable
I within tube lOa and is 2.0 inches square and 67 inches long, and
I 30 tube lOc is slidable within tube lOb and is 1.5 inches square and
66 inches long. These dimensions provide for the mast to have an
extension capability of about 14 feet from the trunnion mounts.
Square mast assembly 10 is preferably mounted diagonally with
respect to base plate 21 such that imaginary lines drawn between
opposite corners of the tubing are parallel and perpendicular to
``- 216~711
WB-9693
base plate 21 when mast 10 is in its horizontal position. Tubes
10a, 10b and 10c include corresponding outboard ends 40a, 40b and
40c, respectively, and tubes 10a and 10b also include outboard
collars 41a and 41b, respectively, welded to the outboard ends
thereof. Tubes 10a, 10b and 10c also include inboard ends 42a, 42b
and 42c, respectively, and tubes 10b and 10c include inboard
colla~s 43b and 43c, respectively, welded to the inboard ends
thereof.
FIGURES 10 and 11 best show the structure of outboard collars
4lb and 4la which are virtually identical, except in size.
Outboard collar 4lb includes lower outer surfaces 44 and 45 and
lower inner surfaces 46 and 47. A rectangular opening 51 i5
provided between outer surface 44 and inner surface 46 and a
rectangular opening 52 is provided between outer surface 45 and
inner surface 47. As seen in FIGURE 11, outboard collar 41a also
includes two rectangular openings 54 and 55, identical to
rectangular openings 51 and 52 of outboard collar 41b. Roller
bearings 56, 57, 58 and 59 are supported in rectangular opening 51,
52, 54l and 55, respectively. Roller bearings 56 and 57 are
rotatably mounted for the outer surfaces thereof to extend beyond
inner surfaces 46 and 47 of tube 41b in order that the lower
adjacent surfaces 61 and 62 of tube 10c are in contact with the
roller bearings. Roller bearings 58 and 59 are mounted in a like
manner. Roller bearings 56-59 are adapted to rotate about a
corresponding support shaft 63 provided, in the preferred
embodiment, by a shoulder bolt having a threaded end 63a received
in a threaded opening therefor, not designated numerically.
Inboard collars 43b and 43c are respectively welded to the
inboard ends 42b and 42c of tubes 10b and 10c, as best shown in
FIGURES 5, 7 and 8. Inboard collarc 43b and 43c have inner ends
located within tubes 10b and 10c, respectively, and the outer ends
of the collars extend radially outwardly such that the outer
surface of inboard collar 43b is adjacent the inside surface 64 of
tube 10a and inboard collar 43c is adjacent the inside surface 65
of tube 10b. As shown in FIGURE 7 two rectangular openings 67 and
--10-- .
2 1 6 5~
WB-9693
68 are provided within inboard collar 43b. Rectangular opening 67
is between the upper inner surface 71, and upper outer surface 73,
and rectangular opening 68 is between the upper inner surface 72
and the upper outer surface 74 of inboard collar 43b. Roller
bearing~ 75 and 76 are supported within rectangular openings 67 and
68, respectively, and are mounted to rotate about a corresponding
support shaft 77 such as a shoulder bolt having an outer threaded
end 77a received in a threaded opening therefor in the collar. As
mounted, roller bearings 75 and 76 contact upper inside surface 64
of tube lOa. As best seen in FIGURES 8 and 9, inboard collar 43c
is a solid stub having an inner end 78 fitted onto end 42c of tube
lOc and an outer end 79. Pockets 81 and 82 are machined into the
upper outer surfaces 83 and 84 of outer end 79, respectively, and
roller bearings 85 and 86 are respectively mounted in pockets 81
and 82 and supported for rotation by corresponding shafts 87
provided by shoulder bolts as described herein with respect to
roller bearings 75 and 76. The outer surfaces of roller bearings
85 and 86 extend above upper outer surfaces 83 and 84 to contact
upper ~side surfaces 65 of tube lOb. Mast assembly 10 is adapted
to be extended and retracted in the horizontal direction and when
inclined relative to horizontal. The orientation of roller
bearings 75, 76, 85 and 86 on the upper outer surfaces of inboard
collars 43b and 43c together with the orientation of roller
bearings 56, 57, 58 and 59 on the lower outer surfaces of outboard
collars 41a and 4'1b support the load of the mast sections during
extension and retraction and restrain downward deflection when mast
assembly 10 is in an extended position. Further, friction between
adjacent tubes lOa, lOb and lOc during extension and retraction is
j significantly reduced by the roller bearing arrangement whereby
j 30 extension and retraction can be achieved with a ~; n; m~l driving
force, and the diagonal orientation of the mast tubes optimizes the
rigidity thereof against vertical deflection when the mast is
extended. It will be appreciated that additional roller bearings
may be added or the orientation of the existing roller bearings may
be changed as the use and potential vertical elevation requirements
--11--
216~7~ 1
. _ .
WB-9693
of mast 10 change. Furthermore, it will be appreciated that while
not shown, outboard collars 41a and 41b coact with inboard collars
43b and 43c during extension of mast 10 to prevent separation of
tubes lOb and lOc from tube lOa or from one another. As is well
known in this respect, for example, each of the collars 41a and 41b
can include a shoulder portion extending radially into tubes lOa
and lOb, respectively, to coact with shoulder portions on collars
43b and 43c, respectively, extending radially outward of tubes lOb
and lOc. During extension, the a~utment of corresponding shoulder
portions prevents tubes lOb and lOc from separating from tube lOa
or from one another.
As best shown in FIGURE 9, inboard collar 43c includes a boss
91 extending axially outwardly from outer end 79 thereof. Boss 91
includes an elliptical portion 92 and a solid cylindrical portion
93. Collar end 79 also includes mounting tabs 94 and 95 which
extend radially inwardly and axially outwardly from opposite
corners thereof. Elliptical portion 92 and solid cylindrical
portion 93 are coaxial and centered on outer surface 96 of inboard
collar 143c, and tabs 94 and 95 extend forwardly from outer surface
96 and have upper surfaces 102 and 103, respectively, in a plane
located directly below a line connecting the corresponding opposite
corners of inboard collar 43c. Cylindrical portion 93 includes two
diametrically opposite tapped holes 97 for receiving hex head bolts
98. Tabs 94 and 95 are tapped at the upper flat surfaces 102 and
103 to provide ``ithreaded holes 104 and 105, respectively for
receiving two cap screws 106 and 107. Boss 91 provides the
interconnection point between the tubes of mast 10 and the drive
assembly for extending and retracting mast 10 which is now
described hereinaf~er.
l 30 As best seen in FIGURES 4-9 an expandable and collapsible
drive member 110 is provided for extending and retracting mast 10.
Drive member 110 has an axis A, is of sheet metal construction and
comprises longitu~;nAlly extending upper and lower portions 111 and
112, respectively, which are of opposed concave contour relative to
one another in the expanded condition of the drive member. Drive
-12-
~8711
Ws-9693
member 110 further includes opposite longitudinally extending
flange portions 113 and 114 extending laterally outwardly from the
corresponding juncture between portions 111 and 112. Specifically,
as shown in the cross-section of FIGURE 7, drive member 110
includes an elliptically shaped opening 115 between concave
portions 111 and 112 in the expanded condition, and this elliptical
cross-section provides strength and rigidity to the drive member
110 when expanded and subjected to both lateral and longitudinal
forces. As will be appreciated from FIGURE 9, drive member 110 i5
attached to mast 10 using boss 91. In this respect, end llOa of
the drive member in its expanded condition is placed over
cylindrical portion 93 and elliptical portion 92, each of which
have dimensions slightly less than or generally equal to the
corresponding diameter dimensions of opening 115. Inner surface
116 of concave portion 111 and inner surface 117 of concave portion
112 facially contact the outer surfaces of elliptical portion 92
and cylindrical portion 93. Drive member 110 is rigidly fastened
to boss 91 and, for this purpose holes 122 are provided in concave
portions 111 and 112 for registry with tapped holes 97 in portion
93, thus to receive hex head bolts 98, and openings 124 and 125 are
respectfully provided in flange portions 113 and 114 for respective
registry with threaded holes 104 and 105 in mounting tabs 94 and
95, thus to receive cap screws 106 and 107. Preferably, drive
member 110 is fabricated such that the distance between the
laterally outermost tips of flanges 113 and 114 is generally equal
to the distance between the opposite inside corners of inside
surface 65 of tube lOb, as shown in FIGURE 7. Therefore, the
laterally outermost tips of flanges 113 and 114 are nested in the
opposite inside corners and work to prevent rotation of drive
member 110 about axis A. This provides added rigidity to mast 10
by providing a relatively stable internal skeletal structure.
Further, in this position, the size of drive member 110 is
;zed within mast 10 to its largest possible dimensions, thus
m~ ; zing the rigidity to be obtained from drive member 110.
Drive member 110 is adapted to be extended and retracted by a
-13-
-
2 1 6 ~
nB-9693
drive unit D and relative to drive unit enclosure 131 in connection
with extending and retracting the mast tubes. As will become
apparent hereinafter, the drive member is adapted to be collapsed
and stored on a storage drum when retracted. When payed from the
drum, drive member 110 is biased to its expanded condition by the
inherent resiliency of members 111 and 112. As shown in FIGURES 4-
6, drive unit D includes a rubber covered drive wheel 132 and
storage or take up drum 133 mounted on storage drum shaft 134 in
drive unit enclosure 131. The opposite ends of storage drum shaft
134 are supported in floating bearing blocks 135 and 136. Floating
bearing blocks 135 and 136 are vertically slidable in bearing block
supports 137 and 138, respectfully, and are biased downwardly
therein by springs 140 and 141. Springs 140 and 141 force floating
bearing blocks 135 and 136 and thus drum 133 downward for drive
member 110 on the drum to engage the outer rubber surface 143 of
drive reel 132. The inner end llOb of drive member 110 is fixed to
take up drum 133 by a mounting block 144.
Drive unit D further includes a drive motor 151 and gear box
152 mou~nted outside drive unit enclosure 131. Preferably, drive
motor 151 is electric or air powered. Advantageously in accordance
with the invention, the ease with which the mast can be extended
and retracted enables motor 151 to be a small motor such as an
automobile power window motor. Drive motor 151 is coupled to the
drive wheel shaft 153 through gear box 152, and shaft 153 is
rotatably supportèd by bearing blocks 154 and 155 which are mounted
on drive unit enclosure 131. As shown in FIGURE 5, storage drum
shaft 134 is located in a vertical plane E and preferably, drive
wheel shaft 153 is located in a vertical plane F. For the reasons
set forth hereinafter, plane E and plane F are offset slightly,
plane F being slightly forward of plane E toward mast assembly 10.
Rotation of drive wheel 132 by drive motor 151 causes rubber
surface 143 to displace drive member 110, thus to rotate take-up
drum 133.
In order to retract mast assembly 10 to a retracted position
relative to drive unit D, drive member 110 is drawn into drive unit
-14-
`_ 21~711
WB-9693
enclosure 131 and about take up drum 133. More particularly in
this respect, drive motor 151 is energized to rotate drive wheel
132 in a counter clockwise direction in FIGURE 5, whereby drive
member 110 moves from right to left and is pinched between take up
drum 133 and drive wheel 132 by the bias of springs 140 and 141
against floating bearing blocks 135 and 136. Counter clockwise
rotation of drive wheel 132 causes clockwise rotation of take up
drum 133 to wind drive member 110 onto the drum, and the offset by
which plane F is located forward of plane E, preferably 0.125 to
0.25 inch, promotes frictional engagement between rubber surface
143 of drive wheel 132 and the drive member to assure a positive
drive with respect to drum 133. The pinching action between drive
wheel 132 and take up drum 133 forces expandable and collapsible
drive member 110 to collapse against its inherent spring bias to a
flat configuration in cross-section. Thus, inner surfaces 116 and
117 are flat and in abutting contact. As the drive member is wound
onto the drum, the floating bearing blocks and springs 140 and 141
exert a constant force as the radial ~ sions of the drum and
drive m~ember thereon progressively increase. This advantageously
promotes use of a small drive motor. Take up drum 133 thus stores
drive member 110 in its collapsed condition. Advantageously, very
little space is required to store drive member 110 in the collapsed
condition thereof.
When it is desired to extend mast 10, the direction of drive
motor 151 is reversed causing drive wheel 132 to rotate in a
clockwise direction in FIGURE 5 and drum 133 counterclockwise,
whereby drive member 110 is payed out from take up drum 133. As
the drive member moves into end 42a of mast tube 10a which extends
into opening 154 therefor in drive unit enclosure 131, the inherent
bias of portions 111 and 112 of drive member 110 causes the latter
to expand to the elliptical shape creating a rigid drive ribbon
which pushes outward on tube 10c through boss 91. Once tube 10c i~
fully extended out of tube 10b, tube 10b is pulled outward from
within tube 10a. Thus, the present invention provides a single
metal band drive member capable of assuming a rigid tubular
-15-
- -
i
Ws-9693
condition for extension and retraction of the mast, and a space
saving collapsed condition which is advantageous for storing the
drive member flat on a reel. This provides a space saving system
over prior art chains and multiple drive systems while ret~;ning
positive extension and retraction characteristics. Further, when
the mast is extended additional rigidity is provided within each of
telescoping sections lOa-lOc by the rigid skeletal structure
provided by the drive member 110.
A preferred method of making expandable and collapsible drive
member 110 is shown in FIGURES 12A-12H. Preferably, drive member
110 is fabricated from a flat sheet 160 of Custom 455 stainless
steel foil which is 0.010 inch thick, 5.5 inches wide and 12 to 14
feet long in the direction of arrow 160a in FIGURE 12A. As shown
in FIGURE 12B, outer flanges 161 and 162, each having a width of
0.375 inches are formed by bending the laterally outer edges of
! sheet 160 upwardly at approximately 45 angles along fold lines 163
and 164 which extend the entire length of sheet 160. All bends
referred to hereinafter extend the entire length of sheet 160. As
shown i~ FIGURE 12C, sheet 160 is then bent upwardly, at 45 angles
along fold lines 165 and 166 which are equidistant from and on
opposite sides of the longitudinal centerline of sheet 160. These
folds form an inner flange portion 167 having a width of 0.750
inches and two panel portions 168 and 169, respectively between
flange portion 167 and outer flanges 161 and 162. Panels 168 and
169 each have a width of 2.0 inches. As shown in FIGURE 12D, sheet
160 is then folded along foldline 170 which is the centerline of
sheet 160. This fold divides inner flange portion 167 into
laterally adjacent inner flange portions respectively extending
upwardly at a 45 angle to panels 168 and 169. Adjacent inner
flange portions are then further folded to the positions shown in
FIGURE 12E in which the inner flange portions are in abutting
contact and panels 168 and 169 are at an angle of 90 to one
another. Inner flange portions 173a and 173b are then welded
together generally along the centerline of the flange portions
using a spot welder 171. As shown in FIGURE 12F, outer flanges 161
~168711
WB-9693
and 162 are then brought together and spot welded in a like manner.
As thus formed, drive member 110 will assume its expanded condition
in which opposed panels 168 and 169 are in concave relative to one
another and have a generally elliptical contour. Upon collapsing
the drive member to a flat condition, the inherent resiliency of
the sheet metal tends to bias the drive member toward the expanded
condition whereby the drive member returns to the latter condition
upon release of the force holding it in the collapsed condition.
Preferably, in order to optimize the spring and strength
characteristics of drive member 110, a 0. 75 inch O.D. support
cylinder 172 having a length corresponding to the length of the
drive member is inserted between panels 168 and 169 and, as
depicted in FIGURE 12G, the drive member is heat treated in a
furnace or the like 173 at about 1050F for eight hours. After
heat treating, tube 172 is removed and, as depicted in FIGURE 12H,
end llOb of the drive member is attached to mounting block 144 on
take up drum 133, and the drive member is collapsed and wound onto
take up drum 133 for installation in a telescoping mast assembly
10. Aslwill be appreciated from the description herein regarding
mast as~embly 10 and drive member 110, and with further reference
to FIGURE 12H, it will be appreciated that flanges 161 and 162
correspond to flange 113 as shown, for example, in FIGURE 9, that
flanges 167a and 167b correspond to flange 114, and that panels 168
and 169 correspond respectively to concave portions 111 and 112 of
the drive member.~
While considerable emphasis has been placed herein on a
specific emboA;~^~t of the invention, it will be appreciated that
other embodiments as well as modifications of the embodiment
disclosed will be suggested or apparent and can be made without
l 30 departing from the principles of the invention. For example,
insofar as the drive member is concerned the mast sections are not
limited to being of polygonal shape and may be of any shape.
Likewise, insofar as the polygonal mast sections are concerned, the
drive member can be other than the tubular drive member disclosed
herein. Additionally, the tubular drive member may be of any
-17-
` 216S711
WB-9693
closed curve or polygonal shape including round, oval or diamond
shaped. While it is preferred that the tubular drive member be
collapsible, the desired rigidity and strength for extending and
retracting the mast are obtained by a tubular contour. Thus,
though a non-collapsible tube would require more space when wound
on a storage reel, it would operate as in the preferred embodiment
to extend and retract a mast. Finally, a collapsible drive member
in accordance with the invention may be filled with a compressible
filling, such as foam rubber, or could be inflatable and thus be
biased ~rom the collapsed to the expanded position. Accordingly,
it is to be distinctly understood that the foregoing descriptive
matter is to interpreted merely as an illustration of the present
invention and not as a limitation of same.
-18-
