Scaffold structure

A scaffold structure comprising a tubular column positioned vertically in use by a base support for supporting a base end portion of the column. Top supporting structure supports a top end portion of the tubular column and is effective to maintain the column vertical in use. The base support and top support impart torsional rigidity to the tubular column. A positionable platform assembly having a platform for standing thereon is positionably mounted on the column for positioning the platform at a selected height above the base end of the column, and to permit adjustment of the height of the platform above the base end of the tubular column.

BACKGROUND OF THE INVENTION 
The present invention relates to a scaffold structure, and more 
particularly to a scaffold structure that is light in weight, strong and 
which has a high degree of torsional stability. 
Various types of scaffold structure are known. The present applicant has 
himself previously patented different scaffold structures which are 
disclosed in U.S. Pat. Nos. 3,760,902 and 3,910,378, respectively. Both of 
these scaffold structures include a ladder which is supported in use in a 
vertical orientation by legs at the bottom of the ladder and by outwardly 
extending support members or arms at the top of the ladder. The support 
members at the top of the ladder rest against a wall or building or other 
structure, in use, to keep the ladder vertical. The known scaffold 
structures further include a platform assembly which is positionable along 
the ladder at different heights. A user of the scaffold structure stands 
on the platform assembly when the ladder is vertical and adjacent a 
structure on which work is to be preformed. As the work progresses the 
user of the scaffold structure can change the position of the platform 
assembly in order to change his position relative to the structure being 
worked on. 
The use of a ladder-like structure in these scaffolds influences the degree 
of torsional stability which they exhibit. The ladder can be thought of as 
a planar structure in that its thickness dimension is small in comparison 
to its length dimension and width dimension. Accordingly, even if the 
ladder is very strong and can support large compressive loads relatively 
smaller loads will cause it to twist about its longitudinal axis. 
Therefore, in order to improve its torsional stability the ladder must be 
made quite strong and this requires massive components with attendant 
increases in expense and weight. 
Additionally, the ladder itself is a relatively expensive component of the 
prior scaffold structures. The ladder is comprised of a pair of parallel 
rails having a plurality of rungs extending therebetween. The fabrication 
of the ladder includes steps of forming a plurality of holes in the rails 
for receiving the rungs, fitting the rungs into the rail holes, and 
securing the rungs and rails together. These steps add to the total cost 
of the prior scaffold structures which incorporate a ladder. 
Finally, because the ladder used in the prior scaffold structures is 
comprised of a plurality of separate parts (rungs and side rails) which 
must be secured together, there is a continuing problem concerning the 
reliability of the ladder. Continuous and repeated use of the ladder puts 
stresses on the joints between the rungs and side rails of the ladder. 
These joints have a tendency to weaken and loosen so that the ladder 
itself may have a tendency to actually come apart. This is a substantial 
safety problem, and it is aggravated with age and use of the scaffold 
structures incorporating a ladder. It requires that the joints between the 
rungs and side rails of the ladder be extremely strong and consequently 
the ladder will be expensive. 
SUMMARY OF THE INVENTION 
It is therefore an object of the present invention to provide a vertical 
scaffold structure having a positionable platform for accommodating a 
person, and which is strong, light and reliable. 
It is another object of the present invention to provide a vertical 
scaffold structure having a positionable platform for accommodating a 
user, and which has a high degree of torsional stability. 
It is another object of the present invention to provide a vertical 
scaffold structure having a positionable platform for accommodating a 
user, and which has a unitary vertical support element. 
In accordance with the objects of the present invention a scaffold 
structure is comprised of a tubular column positioned in use in a 
generally vertical orientation. When so positioned the column has a lower 
base end portion and an upper top end portion. Base supporting means 
supports the base end portion of the tubular column and imparts torsional 
rigidity to the tubular column to maintain the tubular column in a 
generally vertical orientation. Top supporting means supports the top end 
portion of the tubular column and imparts torsional rigidity to the column 
to maintain the tubular column in a generally vertical orientation. The 
scaffold structure also includes a positionable platform assembly 
including a platform dimensioned to permit a worker to stand thereon, and 
mounting means for positionably mounting the platform assembly on the 
tubular column at a selected position along the length thereof to permit 
selection and adjustment of the height of the platform above the base end 
portion of the tubular column. 
In one embodiment the tubular column has a non-circular cross section. In a 
particular embodiment the non-circular cross section is D-shaped and has a 
side surface defined by a cylindrical portion and a flat portion. The flat 
portion of the side surface of the tubular column has holes therethrough 
dimensioned for allowing a worker to insert his hands and feet thereinto 
for climbing up the tubular column. These holes serve the purpose of rungs 
of a ladder. 
The base supporting means comprises a rigid frame and means for engaging 
the lower base portion of the tubular column at positions along the length 
of the lower base portion and on opposite sides of the lower base portion. 
The means for engaging secures the lower base portion at the portions of 
the tubular column engaged to the rigid frame for imparting torsional 
rigidity to the tubular column. 
The rigid frame includes hinge means for defining a hinge mounted on the 
tubular column at the lower base portion thereof at a distance from a 
lower end of the tubular column, and a pair of rigid legs having 
respective first ends spaced apart and respectively extending toward and 
meeting at said hinge means mounted on said tubular column. The pair of 
legs are oriented relative to the tubular column with the lower end of the 
column and the respective first ends of the legs defining a triangle 
generally perpendicular to the tubular column when the tubular column is 
in a generally vertical orientation and being supported by the base 
supporting means. A brace spans between the respective first ends of the 
legs and extends around the tubular column on a side thereof opposite the 
side on which the hinge means is mounted. The brace includes means for 
releasably engaging the bottom end of the tubular column on a side thereof 
opposite the hinge means when the tubular column is oriented generally 
vertical, and for releasing the bottom end of the tubular column as the 
tubular column is pivoted about the hinge means in a direction to move the 
bottom end of the tubular column away from the base. 
The top supporting means is comprised of a rigid frame, and means for 
engaging the top end portion of the tubular column at positions along the 
length of the top end portion on opposite sides thereof and around a 
substantial peripheral portion of the tubular column, for securing the top 
end portion at the positions engaged to the rigid frame for imparting 
torsional rigidity to the tubular column. The rigid frame is comprised of 
a pair of rigid legs having respective first ends spaced apart and 
respectively extending toward and meeting at the tubular column. The pair 
of rigid legs meet and merge together to define the means for engaging the 
top end portion. The means for engaging the top end portion of the column 
comprises a bracket enclosing the tubular column, and a brace spanning 
between the pair of rigid legs and defining a second bracket enclosing and 
gripping the tubular column and having a portion complementary to a 
substantial portion of the cross section of the tubular column for 
preventing rotation of the second bracket and the rigid leg relative to 
the tubular columns. 
The mounting means mounting the positionable platform assembly is comprised 
of the platform which includes releasable engaging means for releasably 
engaging the tubular column for maintaining the platform at a fixed 
position along the length of the tubular column, and positioning means for 
maintaining the platform adjacent the tubular column and for imparting 
torsional rigidity to the tubular column. The positioning means is 
comprised of a frame, means for slideably mounting the frame on the 
tubular column, and means for movably mounting the platform on the frame 
to move between a position with the releasable engaging means of the 
platform engaged with the tubular column, to thereby maintain the platform 
and the mounting means at a fixed position on the tubular column, and a 
second position with the releasable engaging means disengaged from the 
tubular column to thereby allow the platform and the mounting means to 
travel along the length of the tubular column.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
As shown in the drawings, the scaffold structure according to the present 
invention is comprised of a tubular column 1 positioned in use in a 
generally vertical orientation. When the tubular column 1 is positioned 
vertically it has a lower base end portion 2 and an upper top end portion 
3. Base supporting means 10 is attached to the tubular column 1 at the 
lower base end portion 2 thereof and supports the tubular column 1. And as 
discussed below, the base supporting means 10 is also effective for 
imparting torsional rigidity to the tubular column 1. Top supporting means 
70 supports the top end portion 3 of the tubular column 1 and maintains 
the column 1 in a generally vertical orientation. The top supporting means 
70 is also effective to impart torsional rigidity to the column 1. The 
positionable platform assembly 40 includes a platform 41 dimensioned to 
permit a worker to stand thereon, and mounting means for positionably 
mounting the platform 41 on the tubular column 1 at selected positions 
along the length of the column 1. The mounting means permits selection and 
adjustment of the height of the platform 41 above the base end portion 2 
of the tubular column 1. 
The column structure 1 advantageously has a non-circular cross section. In 
the preferred embodiment the cross section of the tubular column 1 is 
D-shaped and the side of the tubular column 1 includes a cylindrical 
portion and a flat portion. The flat portion has a plurality of openings 4 
dimensioned to allow a user of the scaffold structure to insert his hands 
and feet into the openings 4 so that he can climb up the tubular column 1. 
The edges of the openings 4 are rounded to prevent the user's hands and 
feet from being cut as he climbs the column 1. Alternatively, a bar can be 
attached to the column 1 along the bottom edge of each of the openings 4 
to provide comfortable steps and facilitate climbing of the column 1. 
The base supporting means 10 is comprised of a rigid frame which engages 
the lower base portion 2 of the tubular column 1 at positions along the 
length of the lower base portion 2 and on opposite sides of the tubular 
column. The rigid frame includes hinge means 11 defining a hinge mounted 
on the tubular column 1 at the lower base portion 2 thereof at a distance 
from the lower end of the tubular column, and a pair of rigid legs 12, 14 
having respective first ends 13, 15 spaced apart. The pair of rigid legs 
12, 14 respectively extend toward and meet at the hinge means 11 mounted 
on the tubular column 1, and the pair of legs 12, 14 are oriented relative 
to the tubular column 1 with the lower end of the column and the 
respective first ends 13, 15 defining a triangle generally perpendicular 
to the tubular column 1 when it is a vertical orientation and supported by 
the base supporting means 10. A brace 16 spans between the respective 
first ends 13, 15 of the legs 12, 14 and extends around the flat side 
portion of the tubular column 1 opposite the side on which the hinge means 
11 is mounted. The brace 16 includes a pin 17 for releasably engaging the 
bottom end of the tubular column 1 on the flat side portion opposite the 
hinge means 11 when the tubular column is oriented generally vertical. The 
pin 17 releases from the bottom end of the tubular column 1 as the tubular 
column 1 is pivoted about the hinge means 11 in a direction to move the 
bottom end away from the frame, and which is indicated by the arrow in 
FIG. 1. 
The top supporting means 70 is comprised of a rigid frame including a pair 
of rigid legs 71, 73 having respective first ends 72, 74 spaced apart and 
respectively extending toward and meeting at the tubular column 1. The 
pair of rigid legs 71, 73 meet and merge together to define means for 
engaging the top end portion 3 of the tubular column 1. The means for 
engaging the top end portion further comprise a bracket 75 enclosing the 
tubular column. A brace 76 spans between the pair of rigid legs 71, 72 and 
a second brace 77 defines a second bracket enclosing and gripping the 
tubular column and having a portion complementary to a substantial portion 
of the cross section of the tubular column 1 for preventing rotation of 
the second bracket and the rigid legs 71, 73 relative to the tubular 
column 1. In the preferred embodiment the brace 77 has a straight portion 
adjacent the flat side portion of the tubular column 1 while the bracket 
75 holds the brace 77 against the flat portion of the tubular column 1. 
Consequently, rotation of the rigid frame comprising the top supporting 
means 70 is impossible. 
The mounting means for mounting the positionable platform assembly 40 is 
comprised of releasable engaging means on the platform 41 for releasably 
engaging the tubular column 1 for maintaining the platform 41 at a fixed 
position along the length of the tubular column 1. Positioning means for 
maintaining the platform 41 adjacent the tubular column and for imparting 
torsional rigidity to the tubular column is comprised of a frame having a 
pair of opposed rails 42, 43 on opposite sides of the tubular column 1, a 
bracket 44 for slideably mounting the pair of frame rails 42, 43 on the 
tubular column 1, and a bracket 45 for moveably mounting the platform on 
the frame to move between a position with the releasable engaging means of 
the platform engaged with the tubular column 1, to thereby maintain the 
platform 41 and the frame at a fixed height on the tubular column, and the 
position with the releasable engaging means disengaged from the tubular 
column to thereby allow the platform 41 and the frame to travel along the 
length of the tubular column. 
The platform 41 is generally planar and is positioned generally 
perpendicular to the tubular column 1 when the releasable engaging means 
engages the tubular column 1. The bracket 45 for movably mounting the 
platform 41 on the frame has two arms 46,47 each connected to a respective 
edge portion of the platform at positions remote from the tubular column 
1. The arms 46, 47 of the bracket 45 are respectively mounted at the lower 
ends of the frame rails 42, 43 and are mounted to pivot. When the arms 46, 
47 pivot downwardly the platform 41 pivots to a position with its 
releasable engaging means engaged with the tubular column 1. On the other 
hand, when the arms 46, 47 pivot upwardly the platform 41 is displaced 
away from the tubular column 1 and the releasable engaging means disengage 
from the column 1 to allow the entire moveable platform assembly to travel 
along the length of the tubular column 1. 
The releasable engaging means are comprised of a projection 50 along the 
edge of the platform 41 facing the column 1 which is dimensioned to fit 
within an opening 4 in the tubular column 1 and rest on the lower edge of 
such an opening when the arms 46, 47 are pivoted downward. The engagement 
of the projection 50 with an opening 4 prevents downward travel of the 
platform assembly. 
The scaffold structure according to the present invention is used by first 
positioning the base supporting means 10 near a vertical structure, such 
as a wall, on which work is to be performed, and with the positionable 
platform assembly 40 and the top supporting means 70 facing the vertical 
structure. The tubular column 1 is then pivoted slightly forward so that 
the ends 72, 74 of the arms 71, 73 of the top supporting means rest 
against the vertical structure. The cooperation of the top supporting 
means 70 and the base supporting means 10 are together effective for 
maintaining the tubular column 1 in an upright or generally vertical 
position. The position of the top supporting means 70 is adjusted by a 
rope or line attached thereto. 
Thereafter, a user of the scaffold structure raises the safety rail 48, 
steps onto the platform 41, lowers the safety rail 48 and faces the flat 
side portion of the tubular column 1. The user then loops harness 49 over 
his shoulders and commences climbing the tubular column 1 until he reaches 
a height at which he is to perform work on the adjacent vertical structure 
against which the scaffold structure is leaning. The harness 49 is 
connected to the platform 41 or the arms 46, 47 of the bracket supporting 
the platform 41. Consequently, as the user of the scaffold structure 
climbs the tubular column 1 the arms 46, 47 are pivoted upwardly by the 
harness 49 so that the platform 41 pivots upwardly and the projection 50 
is disengaged from the tubular column 1. 
As the user of the scaffold structure continues to climb the harness 49 
pulls the entire moveable platform assembly 40 along with him. When he has 
reached a desired height he need simply only crouch slightly to allow the 
arms 46 and 47 at the platform 41 to pivot downwardly until the projection 
50 of the platform 41 engages the vertical column 1. The height of the 
positionable platform assembly 40 is then fixed and the user of the 
scaffold structure can perform work on the adjacent vertical structure 
against which the scaffold structure is leaning. 
When the user of the scaffold structure has completed his work he simply 
climbs down the scaffold structure in the same manner that he climbed up 
it. First, he again loops the harness 49 over his shoulders and moves 
upwardly slightly to pivot the arms 46, 47 and the platform 41 upwardly to 
disengage the platform 41 from the vertical column 1. He then begins to 
climb down the vertical column 1 using the openings 4 as steps. As he 
climbs down gravity pulls the positionable platform assembly 40 down with 
him. But the harness 49 prevents the positionable platform assembly 40 
from traveling faster then he climbs down the vertical column 1. After he 
has reached the bottom of the scaffold structure he removes the harness 
49, raises the safety rail 48, and steps away from the platform assembly. 
When the scaffold structure is no longer required it is simply carried away 
from the work site. It can be stored in an upright position, as it is 
illustrated in the Figs. Alternatively, it can be stored lying down with 
the base supporting means resting in the normal position and with the 
vertical column 1 pivoted to almost a completely horizontal position with 
the top supporting means resting on the ground or floor. The arms 71, 73 
of the top supporting means are sufficiently long so that the positionable 
platform assemble 40 does not rest on the ground.