TECHNICAL FIELD
The present disclosure relates generally to lightweight scaffolding and, more particularly, to a lightweight, multi-function scaffold.
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 thereof, and a deck that is supported by the side rails. The guide channels slide up and down along the vertical supports of the ladder frames to allow the height of the platform to be adjusted.
The deck of the platform rests on the side rails on either side of the deck and is held in place by a spring-biased latch that pushes the deck down against support surfaces on the side rails. In a conventional multi-function scaffold, the latch comprises an L-shaped pin mounted to the side rail that rotates out of the way while the deck is being put into place, and then rotates back after the deck is in place so that the latch extends over the top surface of the deck to prevent the deck from lifting off of the side rails.
There are some drawbacks with the current latch design. Because the latch extends above the top surface of the deck, it presents a tripping hazard to workers standing on the deck. Also, a worker may accidentally kick and disengage the latch holding the deck in place. If the latch becomes disengaged, the deck may shift and/or dislodge causing the worker to fall.
Accordingly, there is a need for a new design for the latch that eliminates these safety hazards.
SUMMARY
The present disclosure provides a lightweight, multifunction scaffold with an improved safety latch. The scaffold comprises first and second ladder frames, and an adjustable height platform configured to be supported between the first and second ladder frames at a user selected height in an adjustment range. The adjustable height platform comprises a pair of spaced-apart side rails extending between the ladder frames and a deck supported on opposing sides by the side rails. The deck includes at least one recess in a top surface of the deck adjacent each of the opposing sides of the deck. The scaffold further includes at least one latch rotatably mounted to each side rail. Each ladder frame includes a catch element for engagement with a respective recess in the top surface of the deck to secure the deck on the side rails. The latches are movable between a disengaged position allowing the deck to be installed or removed from the side rials and an engaged position in which the catch element extends over a top surface of the deck and engages with a respective one of the recesses in the deck so that the catch element is flush with or below the surface of the deck.
The seating of the latch in the recesses on the top surface of the deck eliminates a trip hazard inherent in conventional designs. Further, the recessing of the latch prevents the worker from accidentally kicking and disengaging the latch while standing on the platform. As a result, the possibility of the deck shifting or being dislodging is reduced, thus reducing the risk of a fall.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective view of a multi-function scaffold including two ladder frames and an adjustable height platform according to a first embodiment.
FIG. 2A is a side view of the scaffold with the platform in a normal orientation and adjusted to a top of the ladder frame.
FIG. 2B is a side view of the scaffold with the platform in an inverted orientation and adjusted to bottom of the ladder frame.
FIG. 3 is a partial perspective view of a side rail assembly including a side rail and guide channel for the adjustable height platform.
FIGS. 4A and 4B are section views of exemplary side rails for the adjustable height platform according to the first embodiment.
FIGS. 5A and 5B are a partial top plan views of the platform showing the latch in disengaged and engaged positions respectively.
FIGS. 6A and 6B are partial perspective views illustrating methods of attaching casters to the ladder frame.
FIG. 7 is a perspective view of the multifunction scaffold with an adjustable height platform according to a second embodiment.
FIG. 8 illustrates one of two side rail assemblies of the adjustable height platform according to the second embodiment.
FIG. 9 is a partial section view of a side rail according to a second embodiment.
FIG. 10 is a partial top view of a side rail showing the configuration of the slots in the side rails of the adjustable height platform.
FIGS. 11 and 12 are perspective view of a latch for securing the deck of the adjustable height platform.
FIG. 13 is a partial perspective view illustrating the installation of the latch.
FIGS. 14A and 14B are a partial top plan views of the platform showing the latch in disengaged and engaged positions respectively.
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 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 shown in FIG. 2A enables the platform 20 to be adjusted to its maximum height. The second orientation shown in FIG. 2B enables the platform 20 to be adjusted to its minimum height. 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 that serve as ladder rungs. 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.
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.
The platform 20 comprises two side rail assemblies 21 that extend between the ladder frames 12 and a deck 40 that is supported by the side rail assemblies. Each side rail assembly 21 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 two orientations, referred to herein as the normal orientation and inverted orientation. Two variations of the side rail 22 are shown in FIGS. 4A and 4B 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. 4A, the side rail 22 comprises a generally C-shaped channel with a central web 22a two parallel flanges 22b. Stiffening flanges 22c extend outwardly from the outer ends of the parallel flanges 22b. In this embodiment, one parallel flange 22b provides a support surface for the deck 40 in the normal orientation and the other parallel flange 22b provides a support surface for the deck 40 in the inverted orientation.
In the embodiments shown in FIG. 4B, the side rail 22 comprises a generally C-shaped channel 22 with a central web 22a and two parallel flanges 22b as previously described with two additional channels 22d attached to the outer ends of the parallel flanges 22b. Like the previous embodiment, the parallel flanges 22b function as support surfaces for the deck 40 in the first and second orientations respectively. The additional channels 22d provide greater strength and rigidity compared to the design in FIG. 5A.
The side rails 22 are equipped with 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 in the deck 40. The latches 42 include a catch element 46 connected to a spring-biased latch pin 44 that pulls the catch element 46 down into contact with the top surface of the deck 40. The latch pin 44 with the attached catch element 46 is rotatable.
To secure the deck 40 in place, the latch 42 is rotated so that the catch element 46 can pass through the slot 40a in the deck 40 while the deck 40 is being lowered into place as shown in FIG. 5A. Once the deck 40 is in place, latch pin 44 is pushed upward and then rotated 90 degrees so that the catch element 42 extends over and engages the upper surface of the deck 40 as shown in FIG. 5B. The latch pin 44 is biased by a spring 48 so that when the latch pin 44 is released, the catch element 46 presses the deck 40 down against the support surface, thus preventing the deck 40 from lifting up off the side rail 22. The top surface of the deck 40 includes a recess or counter-sink 40b into which the catch element 46 seats so that the catch element 46 is flush with or below the top surface of the deck 40. Providing a recess 40b in the top surface of the deck 40 for the catch element 46 reduces the tripping hazard and further reduces the likelihood that the catch element 46 will be accidentally kicked and disengaged.
Referring back to FIG. 3, 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 latches (not shown). In one embodiment, the side rail 22, sleeves 23 and guide channel 24s 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 latch 29 passes through aligned opening 28 and 18 in the guide channel 24 and vertical support 14 respectively. The latch 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 latch 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 latch 32 includes a pair of spaced apart legs 32a connected by a cross member 32b. A bracket 34 supports the latch 32. The bracket 34 includes a pair of openings 36 through which the legs 32a of the latch 32 extend. Springs 38 surrounding each leg 32a of the latch 32 and bias the latch 32 to a locked position. The springs 38 are compressed when the latch 32 is pulled back to disengage the latch 32 and push the latch 32 back to an engaged position when the latch 32 is released.
In some embodiments, the scaffold 10 includes casters 50 disposed at the lower end of each vertical support 14 as shown in FIGS. 6A and 6B. 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 latch 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 the embodiment shown in FIG. 6A, 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 FIG. 2B. In this case, the obstruction of the guide rail 20 prevents insertion of the latch 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 18a in the vertical support and an opening 27 in the guide channel 24 of the side rail 20 so that the latch 56 can be inserted through the aligned openings 58, 18a and 27 to secure the caster 50 to the vertical support 14.
FIG. 6B shows an alternate embodiment, where the caster 50 includes a single opening 54 as previously described. In this embodiment, the opening 18a 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 18a 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. 2B
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.
Additional details of the first embodiment of the multi-function scaffold are described in co-pending U.S. patent application Ser. No. 17/537,163 which is incorporated herein in its entirety by reference.
FIG. 7 illustrates another embodiment of a multi-function scaffold 10 with two ladder frames 12 and an adjustable height platform 20 supported between the two ladder frames 12. As with the first embodiment, 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.
The ladder frames 12 are the same as the first embodiment and the description of the ladder frame 12 is omitted for the sake of brevity. It is also noted that similar reference numbers are used in FIGS. 7-14 to indicate similar components.
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. An example side rail assembly 300 is shown in FIG. 8. In this example, each side rail assembly 300 comprises a side rail 22 and two guide channels 24 at opposing ends of the side rail 22. The side rails 22 are symmetrical about a horizontal plane and configured to provide a support surface 22a for the deck 40 of the platform 20 in both a first orientation (guide channels extending down from side rail 22) and a second orientation (guide channel extending up from side rail 22). The platform 20 can be used in either orientation. The ability to reverse the platform 20 extends the range of adjustment, increases the maximum height and decreases the minimum height.
The guide channels 24 comprises a C-shaped channels 24 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. 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 latch 32 that engages with the aligned openings and in the guide channel 24 and vertical supports 14 respectively to lock the side rail 22 at a desired height. The U-shaped latch 32 is biased by springs to an engaged position. To adjust the height of the platform, the latch is pulled back to disengage the latch from the holes 18 in the vertical supports 14. Once disengaged, the platform 20 can be adjusted in height to any desired position in the adjustment range. When the platform 20 is adjusted to the desired height, span pins 34 can be inserted through holes in the guide channel 24 that align with the holes 18 in the vertical supports 14 as a failsafe. The span pins 34 secure the platform 20 at the desired height even if the releasable locking mechanism fails or disengages.
The side rails 22 in the second embodiment are equipped with removable latches 42, also referred to as locking pins 42, to hold the deck 40 down once the deck 40 is put in place. FIG. 9 shows the side rails 22 with the deck 40 and latches 42 installed. The installation of the latch 42 is the same in both orientations of the platform 20. The cross-section of the side rail 22 is the same as shown in FIG. 4B.
As shown in FIGS. 10, specially formed slots 23 are formed in the outer surfaces 22b of the side rail 22. The slots 23 in the outer surfaces 22b are vertically aligned. As explained in more detail below, the latches 42 can be installed in the vertically aligned slots 23 in both the first and second orientations. The slots 23 each include a channel 23a, depicted in FIG. 5 as an elongated narrow section of the slot 23. The slots 23 each also include a large hole 23c formed near one end of the channel 23a and a smaller hole 23b formed near the opposing end of the channel 23a. The holes 23b, 23c located along the length of the channel 23a facilitate installation of the latch 42 as herein described. When a need arises to reverse the platform 20, the latches 42 can be removed and re-installed in the new orientation without use of any tools. This eliminates the need to have separate latch mechanisms for use in each orientation.
The design of an example latch 42 is shown in FIGS. 11 and 12. The latch 42 comprises a shaft 44 and a catch element 46 that is press fit and/or spot welded onto one end of the shaft 44. The shaft 44 includes a reduced diameter section 44a near the end on which the catch element 46 is installed and a pair of spaced opening 44c to receive respective roll pins 44b, each of which forms one or more protrusions on the shaft 44. The catch element 46 has a generally circular shape with a flat on one side, i.e. a D-shape. Additionally, the catch element 46 includes integral detents formed by stamping on the underside thereof to engage in the slots 23 as hereinafter described. When the latch 42 is installed, a biasing member (e.g., a coil spring 48 in the examples of FIGS. 6 and 7) biases the catch element into engagement with the deck 40 to secure the deck 40 to the platform and to prevent the deck 40 from lifting off the support surface 22a. The spring 48 bears at one end on the inside of the side rail 22 and at the other end on a pin 44b. The spring can be ground and closed to keep the starting coil at top from accidentally threading itself up through smaller hole 23b in the slot 23 when the latch is installed.
FIG. 13 is a perspective illustrating how a latch 42 is installed. No tools are required to remove and install the latch. The latch 42 is installed by inserting it at an angle through vertically aligned upper and lower slots 23 as shown in FIG. 8 and then sliding the upper end of the latch 42 along the upper slot 23. The shaft 44 is inserted at an angle through the large hole in the upper slot 23, which is sized to allow the shaft 44 and spring 48 to pass through the slot 23, with the lower end passing through the smaller hole in the lower slot 23. After the latch 42 is inserted at an angle, the latch 42 is rotated to the position shown in FIG. 4 so that the roll pin 44b in the lower end of the shaft 44 prevents withdrawal of the latch 42. The latch 42 is pushed up slightly to compress the spring 48. The roll pin 44b in the lower end of the shaft 44 limits the upward movement of the latch 42 but the location should provide enough room to align the reduced diameter section 44a with the upper slot 23. When the reduced diameter section 44a is aligned with the upper slot 23, the reduced diameter section 44a can slide along the narrow section of the slot 23 until the shaft 42 is vertically aligned in the smaller set of holes in the slots 23. In this way, the upper end 44d of the shaft 44 is moved away from the larger hole 23c of the upper slot 22c over toward the smaller hole 23b of the upper slot 22c, while the lower end 44e of the shaft remains in the smaller hole 23b of the lower slot 22c. When the force compressing the spring 48 is removed, the spring 48 pushes the catch element 46 down to engage the detents 46a of the catch element 46 in the slots 23 to prevent rotation of the latch 42.
To install the deck 40, the latch 42 is pushed up slightly to rotate the latch 42 so that the flat side of the catch element 46 faces the deck 40 as shown In FIG. 14A. Once the deck 40 is put into place, the latch 42 is rotated 180 degrees so that the curved side extends over and engages the top of the deck 40 as shown in FIG. 14B. Even if the latch 42 is accidentally kicked and rotated, the deck 40 will be held in place unless the latch is rotated a full 180 degrees, thus providing a higher degree of safety than conventional designs currently in use. The shape of the catch element 46 reduces the risk of kicking and accidentally disengaging the catch element 46. Additionally, recess or countersink 40b is provided in the top surface of the deck 40 into which the catch element 46 seats so that the catch element 46 is flush with or below the top surface of the deck 40. Providing a recess 40b in the deck 40 reduces the tripping hazard and further reduces the likelihood that the catch element 46 will be accidentally kicked and disengaged.
Additional details of the second embodiment of the multifunction scaffold are described in co-pending U.S. patent application Ser. No. 17/716,781 filed on Apr. 8, 2022, which is incorporated herein in its entirety by reference.
Patent Application
20230272627
