The present disclosure relates generally to lightweight scaffolding and, more particularly, to a lightweight, multi-function scaffold with a reversible platform.
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.
The present disclosure provides a lightweight scaffold designed to provide a greater range of height adjustment while at the same time greatly increasing stability. The scaffold comprises an adjustable height platform supported between two ladder frames. Greater stability is achieved in by increasing the length of the guide channels. The height adjustment range is increased 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. In the first orientation, the adjustable height platform is vertically movable between a first threshold and a maximum height. 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.
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.
Referring now to the drawings,
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
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 18a extend transversely through the lower end of each vertical support 14. These opening 18a are used to secure casters 50 to the vertical supports 14 when the side rail 20 is in the lowermost position as will be hereinafter described.
Referring to
In the embodiments shown in
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 22b of the side rail 22 and are configured to project up through slots 40a (
Referring back to
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 32a connected by a cross member 32b. A bracket 34 supports the locking pin 32. The bracket 34 includes a pair of openings 36 through which the legs 32a of the locking pin 32 extend. Springs 38 surrounding each leg 32a 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
In some embodiments, the scaffold 10 includes casters 50 disposed at the lower end of each vertical support 14 as shown in
In one embodiment, the stem 52 further includes a second opening 58 oriented 90 degrees relative to the first opening 54. The second opening 56 is for use when the platform 20 is adjusted to the minimum height as shown in
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 18a 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
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
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.
The present application claims benefit of U.S. Provisional Application No. 63/119,436, which was filed Nov. 30, 2020, and U.S. Provisional Application No. 63/168,780, which was filed Mar. 31, 2021, the disclosures of each of which are incorporated herein by reference in their entirety.
Number | Date | Country | |
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63119436 | Nov 2020 | US | |
63168780 | Mar 2021 | US | |
63171312 | Apr 2021 | US |