Patent Publication Number: US-2023151620-A1

Title: Multi-Function Scaffold with Reversible Platform

Description:
RELATED APPLICATIONS 
     This application is a continuation-in-part of PCT/US2021/061010, filed 29 Nov. 2021; and claims benefit of U.S. Provisional Application No. 63/119,436, filed 30 Nov. 2020, and U.S. Provisional Application No. 63/168,780, filed 31 Mar. 2021, and U.S. Provisional Application No. 63/171,312, filed 6 Apr. 2021; the disclosures of each of which are incorporated herein by reference in their entirety. 
    
    
     TECHNICAL FIELD 
     The present disclosure relates generally to lightweight scaffolding and, more particularly, to a lightweight, multi-function scaffold with a reversible platform. 
     BACKGROUND 
     Lightweight scaffolds made from metal tubing are commercially available for use when working close to the ground. One such scaffold comprises an adjustable height platform supported between two ladder frames. The platform includes two side rails with guide channels at each end that slide up and down along the vertical supports of the ladder frames. Casters insert into the lower ends of the vertical supports so that the scaffold can roll on the floor or other support surface. Also, the scaffolds are configured to be stacked vertically. Stability of the scaffold is provided by a braces that connect the guide channels to the platform. 
     The design of lightweight scaffold involves a trade-off between the height adjustment range and stability. Lightweight scaffolds tend to be less stable than typical heavy-duty scaffolding. Stability can be increased in two ways: by reducing the amount of play between the vertical supports of the ladder frame and the guide channel makes, and by reducing the flex of the ladder frame at the upper end of the adjustment range. Increasing the length of the guide channels at the ends of the side rails achieves both of these stability enhancements. 
     While increasing the guide channel length provides greater stability, it comes at the cost of significantly less adjustment range. The movement of the guide channels that slide along the legs is limited by interference with other components of the scaffolding. For example, when the platform is lowered, the guide channels may come into contact with other components. Because the guide channels extend down from the platform, the interference with other components establishes a lower limit on the platform height. Reducing the length of the guide channel would enable the platform to be lowered closer to the ground but would make the scaffolding less stable. Therefore, the length of the guide channels for lightweight scaffolding currently on the market compromises the adjustment range in order to improve stability. 
     SUMMARY 
     The present disclosure provides a lightweight scaffold designed to provide a greater range of height adjustment while at the same time greatly increasing stability. Greater stability is achieved in by increasing the length of the guide channels. Greater range of height adjustment is achieved by making the platform reversible so that it can be mounted between the ladder frames in either a first orientation or in a second orientation. Making the platform reversible increases the range of height adjustment in two ways. First, orienting the platform so that the guide channels extend in an upward direction allows the platform to be lowered closer to the ground than conventional designs. When the platform is oriented with the guide channels extending downwardly, the increased length enables the platform to be raised above an upper end of the ladder frame while maintaining stability. The stability can be enhanced by properly clamping the guide channel to the vertical supports of the ladder frame to remove play between the guide channels and the vertical supports. 
     According to another aspect of the disclosure, further increase in the adjustment range is achieved by providing openings in the guide channels that align with the openings in the vertical supports of the ladder frame used for connecting a caster or other ground engaging member. In a conventional scaffold, the caster or other ground engaging member includes a stem that inserts into the lower end of the vertical supports and is secured by a span pin that passes through aligned openings in the vertical support and in the stem of the caster. The guide channel cannot extend below the span pin so the span pin limits the range of movement. In exemplary embodiments disclosed herein, an opening is provided in the guide channel that aligns with the openings in the vertical support and caster stem when the platform is lowered to a predetermined height. The addition of the opening allows the platform to be lowered below the span pin to further increase the adjustment range. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a perspective view of a scaffold including two ladder frames and an adjustable height platform according to one exemplary embodiment. 
         FIG.  2 A  is a side view of the scaffold with the platform adjusted to a top of the ladder frame. In some embodiments, this is the maximum height. 
         FIG.  2 B  is a side view of the scaffold with the platform adjusted to a height above the top end of the ladder frame. 
         FIG.  3    is a side view of the scaffold with the platform adjusted to minimum height. 
         FIG.  4 A  is a partial perspective view of a side rail and guide channel for the adjustable height platform. 
         FIG.  4 B  is partial perspective view of a side rail and guide channel for the adjustable height platform with the platform extending above the height of the ladder frame. 
         FIGS.  5 A and  5 B  are cross section views of exemplary side rails for the adjustable height platform. 
         FIG.  6    is a partial top plan view of the platform showing a locking mechanism to secure the deck to the side rails of the adjustable height platform. 
         FIG.  7    illustrates compact stacking of two ladder frames for shipment or storage. 
         FIG.  8    is an exploded perspective view illustrating a first method of mounting a caster to the scaffold. 
         FIG.  8 A  is a perspective view illustrating an alternate method for mounting the caster to the scaffold 
         FIG.  9    is an exploded perspective view of a stacking pin for the scaffold. 
         FIG.  10    schematically illustrates the adjustment range of the adjustable height platform. 
         FIG.  11    illustrates a method of adjusting the height of the platform for the scaffold. 
         FIG.  12    shows a perspective view of an alternative embodiment of a side rail assembly with a curved brace. 
         FIG.  13    shows a cross-sectional view of the side rail of  FIG.  12    taken along XIII-XIII. 
         FIG.  14    shows a partial perspective view of a scaffold using the side rail assembly of  FIG.  12   , with the side rail in the second orientation for adjustment of the platform to a minimum height. 
     
    
    
     DETAILED DESCRIPTION 
     Referring now to the drawings,  FIG.  1    illustrates a multi-purpose scaffold  10  according to an exemplary embodiment. The multi-purpose scaffold  10  comprises two ladder frames  12  and an adjustable height platform  20  supported between the two ladder frames  12 . As described in greater detail below, the side rails  22  of the adjustable height platform  20  can be mounted between the ladder frames  12  in two different orientations depending on a height requirement for a task. The first orientation enables the platform  20  to be adjusted to its maximum height. The second orientation enables the platform  20  to be adjusted to its minimum height. In one embodiment, the adjustment range is between a maximum height of about 78.5 inches and a minimum height of about 10 inches providing an adjustment range of 68.5 inches. For comparison, the maximum height for conventional lightweight scaffolds of this type is about 71 inches and the minimum height for conventional lightweight scaffolds is about 27 inches providing an adjustment range of only 44 inches. In this example, the design enhancement yield a 55% increase in the adjustment range. The first orientation is for relatively greater heights, i.e., farther from the ground, and the second orientation is for relatively lower heights, i.e., closer to the ground. 
     Each ladder frame  12  comprises two vertical supports  14  connected by two or more cross members  16 . The vertical supports  14  and cross members  16  are preferably made of a metal tubing or other tubular material. The cross members  16  are preferably welded at each end to respective ones of the vertical supports  14  so that each ladder frame  12  is a unitary structure. 
     In one embodiment, the vertical supports  14  have a square or rectangular cross-section and the cross members  16  have a circular cross-section. The outside diameter of the cross members  16  is less than the width of the vertical support  14 . The cross members  16  can be offset from the center of the vertical supports  14  and the ends of the cross members  16  can be crimped or compressed to facilitate more compact stacking as shown in  FIG.  7   . 
     A series of aligned openings  18  extend through the vertical supports  14  perpendicular to the plane of the ladder frame  12  and are spaced 2 inches apart. As will be hereinafter described in more detail, the openings  18  are engaged by a releasable locking mechanism  30  on the platform  20  to secure the platform  20  at a desired height between the ladder frames  12 . Additionally, openings  18   a  extend transversely through the lower end of each vertical support  14 . These opening  18   a  are used to secure casters  50  to the vertical supports  14  when the side rail  22  is in the lowermost position as will be hereinafter described. 
     Referring to  FIG.  4 A , the platform  20  comprises two side rail assemblies that extend between the ladder frames  12  and a deck  40  that is supported by the side rail assemblies. Each side rail assembly comprises a side rail  22  and two guide channels  24  at opposing ends of the side rail  22 . The side rails  22  are configured to provide a support surface for the deck  40  in both a first orientation and a second orientation. Two variations of the side rail  22  are shown in  FIGS.  5 A and  5 B  respectively. In both cases, the cross section of the side rail  22  is symmetrical about a horizontal plane H. In the embodiment shown in  FIG.  5 A , the side rail  22  comprises a generally C-shaped channel with a central web  22   a  two parallel flanges  22   b . Stiffening flanges  22   c  extend outwardly from the outer ends of the parallel flanges  22   b . In this embodiment, one parallel flange  22   b  provides a support surface for the deck  40  in a first orientation and the other provides a support surface for the deck  40  in the second orientation. In effect, the stiffening flanges  22   c  and the parallel flanges  22   b  form upper and lower bounded notches that include the support surfaces for the first and second orientations, respectively, and these bounded notches are disposed inward relative to the stiffening elements in the form of flanges  22   c . 
     In the embodiments shown in  FIG.  5 B , the side rail  22  comprises a generally C-shaped channel with a central web  22   a  and two parallel flanges  22   b  as previously described with two additional channels  22   d  attached to the outer ends of the parallel flanges  22   b . Like the previous embodiment, the parallel flanges  22   b  function as support surfaces for the deck  40  in the first and second orientations respectively. Thus, like described above, the channels  22   d  and the parallel flanges  22   b  form upper and lower bounded notches that include the support surfaces for the first and second orientations, respectively, and these bounded notches are disposed inward relative to the stiffening elements in the form of the channels  22   d . The additional channels  22   d  provide greater strength and rigidity compared to the design in  FIG.  5 A . 
     The side rails  22  are equipped with internal latches  42  to hold the deck  40  down once the deck  40  is put in place. The latches  42  are mounted to the parallel flanges  22   b  of the side rail  22  and are configured to project up through slots  40   a  ( FIG.  6   ) in the deck  40 . The latches  42  include a catch element  42   a  connected to a spring-biased latch pin  42   b  that pulls the catch element  42   a  down into contact with the top surface of the deck  40 . The latch pin  42   b  with the attached catch element  42   a  is rotatable. To secure the deck  40  in place, the latch pin  42   b  and attached catch element  42   a  are rotated so that the catch element  42   a  can pass through the slot  40   a  in the deck  40  while the deck  40  is being lowered into place. Once the deck  40  is in place, latch pin  42   b  is pushed upward and then rotated so that the catch element  42  engages the upper surface of the deck  40  as shown in  FIG.  6   . The latch pin  42   b  is biased by a spring  42   c  so that when the latch pin  42   b  is released, the catch element  42   b  presses the deck  40  down against the support surface, thus preventing the deck  40  from lifting up off the side rail  22 . 
     Referring back to  FIG.  4 A , the ends of each side rail  22  connect directly or indirectly to a C-shaped guide channel  24  sized to fit around the vertical supports  14  of the ladder frames  12 . In one embodiment, a square sleeve  23  is interposed between each end of the side rail  22  and the guide channel  24  for mounting a safety rail to the platform. The sleeve  23  is configured to receive posts P of the safety rail (not shown), which can be secured to the sleeve  23  by locking pins (not shown). In one embodiment, the side rail  22 , sleeves  23 , and guide channels  24  for each side rail assembly are welded together to form a unitary structure. 
     The guide channels  24  comprises a C-shaped channel and are configured to slide along the vertical supports  14  of the ladder frames  12  at each end of the scaffold  10  to adjust the height of the platform  20 . Two openings  26  are formed in the inner flanges of each guide channel  24  for locking the guide channel  24  at a selected height as hereinafter described. The openings  26  are spaced to align with the openings  18  in the vertical supports  14  of the ladder frame  12  at preselected heights. The openings  26  in the guide channels  24  are engaged by a releasable locking mechanism  30  (described below) on the platform  20  to secure the platform  20  at a desired height between the ladder frames  12 . A third opening  28  is formed near a lower end of the guide channel  24  and aligns with an opening  18  in the vertical support  14 . A locking pin  29  passes through aligned opening  28  and  18  in the guide channel  24  and vertical support  14  respectively. The locking pin  29  serves as a failsafe and provides additional safety in case the locking mechanism  30  inadvertently disengages. Diagonal braces  25  connect a lower end of each guide channel  24  to the side rail  22  to increase the strength and rigidity of the assembled scaffold  10 . The increased stability enhances worker’s confidence when standing on the scaffold. 
     Each guide channel  24  includes a releasable locking mechanism  30  for locking the platform  20  at a desired height. In one embodiment, the releasable locking mechanism  30  comprises a U-shaped locking pin  32  that engages with the aligned openings  26  and  18  in the guide channel  24  and vertical supports  14  respectively to lock the side rail  22  at a desired height. Each locking pin  32  includes a pair of spaced apart legs  32   a  connected by a cross member  32   b . A bracket  34  supports the locking pin  32 . The bracket  34  includes a pair of openings  36  through which the legs  32   a  of the locking pin  32  extend. Springs  38  surrounding each leg  32   a  of the locking pin  32  and bias the locking pin  32  to a locked position. The springs  38  are compressed when the locking pin  32  is pulled back to disengage the locking pin  32  and push the locking pin  32  back to an engaged position when the locking pin  32  is released. 
     The guide channel  24  as herein described is increased in length in comparison to prior art designs. The increased length enables the platform to be adjusted to a height above the top end of the ladder frames as shown in  FIG.  4 B . By increasing the length of the guide channels  24  from about 18 inches to about 23 inches, the maximum height for the platform can be increased from about 71 inches to about 78.5 inches. 
     In some embodiments, the scaffold  10  includes casters  50  disposed at the lower end of each vertical support  14  as shown in  FIG.  8   . Each caster  50  includes a stem  52  that extends into the lower end of a vertical support  14 . The stem  52  is sufficiently long to overlap at least two openings  18  in the lower end of the vertical support  14 . The stem  52  of the caster  50  includes an opening  54  that is located to align with an opening  18  in the vertical support  14  when the stem  52  of the caster  50  is inserted into the vertical support  14 . A locking pin  56  passes through aligned openings  54  and  18  in the caster  50  and vertical support  14  respectively to secure the caster  50  to the vertical support  14 . 
     In one embodiment, the stem  52  further includes a second opening  58  oriented 90 degrees relative to the first opening  54 . The second opening  58  is for use when the platform  20  is adjusted to the minimum height as shown in  FIG.  3   . In this case, the obstruction of the guide rail  20  prevents insertion of the locking pin  56  through the aligned openings  54  and  18  in the caster  50  and vertical support  14 . In this case, the second opening  58  aligns with opening  18   a  in the vertical support and an opening  27  in the guide channel  24  of the side rail  20  so that the locking pin  56  can be inserted through the aligned openings  58 ,  18   a  and  27  to secure the caster  50  to the vertical support  14 . 
       FIG.  8 A  show an alternate embodiment, where the caster  50  includes s single opening  54  as previously described. In this embodiment, the opening  18   a  in the vertical support  14  is vertically aligned with an opening  18 . In this case, the caster  50  can be turned 90 degrees so that the opening  54  aligns with opening  18   a  in the vertical support and the opening  26  in the guide channel  24  of the side rail  20  when the side rail is in the lowermost position as shown in  FIG.  3   . 
     In some embodiments, the casters  50  can be replaced by footpads, level jacks or socket levelers (not shown) or other ground-engaging member. comprising a generally flat pad that contacts the ground or underlying surface and a stem that extends into that extends into the lower end of a vertical support  14 . 
     In a conventional scaffold  10 , the guide channel  24  cannot extend below the span pin  56  securing the caster  50  or other ground engaging member the lower end of the vertical supports  14 . Thus, the span pin  56  limits the range of movement at the lower end of the adjustment range. In exemplary embodiments disclosed herein, an opening  27  is provided at each end of the guide channel  24  that aligns with the openings  18   a  and  58  in the vertical support  14  and caster stem  52  respectively when the platform  20  is lowered below the span pin  56 . The addition of the openings  27  allows the platform  20  to be lowered below the span pin  56  to further increase the adjustment range. In a conventional scaffold, the span pin  56  is 2.5 inches above the caster flange. Providing the additional openings  27  in the guide channel allow the platform to be lowered by an additional 2.5 inches plus ½ the diameter of the span pin  56 . 
     In some embodiments, the ladder frames  12  include removable stacking pins  60  at the upper ends of the vertical supports  14 . As shown in  FIG.  9   , the stacking pins  60  include a threaded end  60   a  that screws into an opening  62   a  in a mounting block  62  at the upper end of the vertical supports  14 . The ability to remove the stacking pins enables more compact packaging for shipments and storage. Additionally, the design enables the use of interchangeable stacking pins of different size and/or shape. 
     When assembled, the scaffold  10  provides a free-standing, self-supporting structure. Outriggers  70  can be used with the scaffold to increase stability by providing a wider base. Conventional outriggers  70  for lightweight scaffolds are designed to extend out from the sides of the scaffold in a lateral direction, i.e., perpendicular to the longitudinal axis. This arrangement reduces the risk of tipping sideways but does not improve stability in the longitudinal dimension. 
     The multifunction scaffold as herein described provides a greater range of adjustment in the height of the platform  20 . To obtain maximum height, the side rails  22  of the platform  20  are mounted between the ladder frames  12  in a first orientation as shown in  FIGS.  2 A- 2 B . To obtain the minimum height, the side rails  22  of the platform  20  are inverted and mounted between the ladder frames  12  in a second orientation as shown in  FIG.  3   . 
       FIG.  10    is a schematic illustration showing the range of adjustment of the platform  20  in the first and second orientations. For reference, the term first orientation is used as a label for the configuration shown in  FIGS.  2 A- 2 B  and the term second orientation is used a label for the configuration shown in  FIG.  3   . In the first orientation, the downward movement is limited by the guide channels  24 , which extend downward in this configuration. The lower bound of the downward movement is referred to as the first threshold. In this orientation, the platform  20  is adjustable to a height between the first threshold and a maximum height. In the second orientation, the guide channel extends upward and limit the upward movement of the platform  20 . The upper bound of the movement is referred to as the second threshold. In this orientation, the platform  20  is adjustable to a height between the minimum height and the second threshold. 
       FIG.  11    illustrates an exemplary method of configuring the scaffolding for use. Prior to assembly of the scaffold  10 , user determines a height requirement for a particular task (block  110 ). Based on the height requirement, the user selects either the first orientation or the second orientation (block  120 ). If the height requirement is greater than the first threshold, the user can install the platform  20  in the first orientation (block  130 ). If the height requirement is less than the second threshold, the user can install the platform  20  in the second orientation (block  140 ). If the height requirement is greater than the first threshold and less than the second threshold, the user can install the platform  20  in either the first orientation or the second orientation (block  150 ). 
       FIG.  12    shows an alternative embodiment of a side rail assembly, with a curved brace  25 . As can be seen in  FIG.  13   , the brace  25  is located outwardly laterally offset relative to the flanges  22   b  forming the support surfaces for the deck  40 . Thus, for the embodiment of  FIG.  13   , the brace  25  mates to the side rail  22  at the stiffening element, which is located laterally outward (to the left in  FIG.  13   ) relative to the corresponding flange  22   b . This lateral offset of the brace  25  allows the deck  40  to engage the flange  22   b  closest to the brace  25  (the lower flange  22   b  in  FIG.  13   ) when the side rails  22  are in the second (or inverted) orientation (see  FIG.  3   ). The braces  25  are advantageously located entirely outside the vertical projection of the perimeter of the deck  40  so that the braces  25  do not interfere with placement of the deck  40  against the support surfaces of the side rail  22  when the side rail assembly is inverted. See  FIG.  14   . Note that the lateral offset of the brace  25  applies at least to the end of the brace mated to the side rail  22 , but that the end of the brace  25  mating to the guide channel  24  may or may not be laterally offset relative to the center of the guide channel, as is desired. 
     As can also be seen in  FIG.  13   , a plurality of alignment pins  21  are optionally mounted to the side rail  22  so as to extend from one or optionally both support surfaces of the side rail  22 . The alignment pins  21  are intended to extend into/through corresponding holes in the deck  40  to facilitate maintaining alignment of the deck relative to the side rails  22 . Also shown in  FIG.  14    are alternative embodiments of locking pins  42 , which extend through the stiffening element of the side rail  22 , and are described more fully in PCT/US2022/030542, filed 23 May 2022 (the disclosure of which is incorporated herein by reference in its entirety). Further shown in  FIG.  14    is that the releasable locking mechanism  30  is advantageously vertically spaced from the side rail  22  so that there is a gap between the releasable locking mechanism  30  and the side rail  22 . The concepts illustrated in  FIGS.  12 - 14   , such as the laterally offset braces  25 , the alignment pins  21 , and the spacing of the releasable locking mechanism  30  from the side rail  22 , may optionally be present in the other embodiments of the scaffold  10  described herein, alone or in any combination. 
     A lightweight, multi-function scaffold with reversible side rails is more versatile than conventional multifunction scaffolds and enables use of the scaffold over a greater range of height requirements while increasing stability. When the side rails are in the first orientation, the adjustable height platform is vertically movable between a first threshold and a maximum height. When the side rails are in the second orientation, the adjustable height platform is vertically movable between a second threshold and a minimum height. The ranges of movement in the first and second orientations may overlap.