Ladder Frame for a Scaffold Having Removable Ladder Rungs

Abstract

An improved multi-function scaffold connects end-to-end with similar scaffolds to provide a longer working surface. The scaffold includes two walk-through ladder frames with detachable rungs. When two scaffolds are joined, the detachable rungs on the ladder frame between the joined scaffolds can be removed to enable workers to move freely between scaffolds without obstruction.

Description

TECHNICAL FIELD

[0001] The present disclosure relates generally to lightweight scaffolding and, more particularly, to connectable lightweight, multi-function scaffolds that connect with other like scaffolds to form a wall unit.BACKGROUND

[0002] Lightweight scaffolds made from metal tubing are commercially available for use when performing tasks such as painting. 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.

[0003] The multi-function scaffolds are typically about six foot in length and designed to be moved on casters. When performing a task, such as painting, workers need to reposition the scaffold regularly in order to complete their work. Stopping work to reposition the scaffold results in loss of productivity and increases the chances of injury when climbing on or off the scaffold.

[0004] Co-pending application Ser. No. 18 / 815,493 (the '493 application) filed on Aug. 18, 2024 titled Connectable Multi-Function Scaffold discloses a multi-function scaffold that is designed to join end-to-end with other similar scaffolds to provide a longer working surface. The multi-function scaffold described in the '493 application includes regular ladder frames that are used at the ends of the connected scaffolds, and walk-through ladder frames that are used between connected ladder frames. Once the scaffolds are set up, workers can move between scaffolds on a level surface to complete their task without the need to stop and reposition the scaffold. Thus, worker productivity is increased and the risk of an accident when the workers climb on and off the scaffold is reduced.SUMMARY

[0005] The present disclosure provides an improvement to the connectable multi-function scaffold disclosed in the '493 application. Specifically, the connectable, multi-function scaffold as herein described uses only one type of ladder frame, i.e., a walk-through ladder frame with detachable rungs. In this design, the detachable rungs can be removed from the shared ladder frame between two connected scaffolds to allow workers to move freely between scaffolds without obstruction while the detachable rungs remain installed on the non-shared ladder frames at the ends of the connected scaffolds. The detachable rungs can also be removed from the ladder frame at one end to make access to the platform easier. This design reduces the number of parts that need to be inventoried, reduces the cost of the scaffold, and reduces the amount of effort required to reconfigure the scaffolds.

[0006] One aspect of the disclosure relates a ladder frame for a multi-function scaffold having detachable rungs. The ladder frame comprises one or more fixed rungs extending between and connected, directly or indirectly, to the vertical supports. A pair of handrail assemblies are connected to and spaced inward of the vertical supports. The handrail assemblies define a pass-through allowing a user to step through the ladder frame between the vertical supports. One or more detachable ladder rungs are configured to removably attach to the handrail assemblies.

[0007] Another aspect of the disclosure relates a multi-function scaffold comprising an adjustable height platform mounted between two ladder frames. Each ladder frame comprises two vertical supports, one or more fixed rungs, and one or more detachable rungs. The fixed rungs extend between and connect, directly or indirectly, to the vertical supports of the ladder frame. A pair of handrail assemblies are connected to and spaced inward of the vertical supports. The handrail assemblies define a pass-through allowing a user to step through the ladder frame between the vertical supports. One or more detachable ladder rungs are configured to removably attach to the handrail assemblies.

[0008] Another aspect of the disclosure relates a multi-function scaffold comprising an adjustable height platform that can be mounted between two ladder frames in a first orientation and a second orientation. The adjustable height platform comprises a pair of reversible side rails for supporting a deck. The side rails include first and second supports for supporting the deck in the first and second orientation respectively. Guide channels are attached at opposing ends of each side rail for slidably mounting the side rails to the vertical supports of the ladder frame. Each ladder frame comprises two vertical supports, one or more fixed rungs and one or more detachable rungs. The fixed rungs extend between and connect, directly or indirectly, to the vertical supports of the ladder frame. A pair of handrail assemblies are connected to and spaced inward of the vertical supports. The handrail assemblies define a pass-through allowing a user to step through the ladder frame between the vertical supports. One or more detachable ladder rungs are configured to removably attach to the handrail assemblies.BRIEF DESCRIPTION OF THE DRAWINGS

[0009] FIG. 1 is a perspective view of a multi-function scaffold with the platform in a first orientation.

[0010] FIG. 2 is a perspective view of a multi-function scaffold with the platform in a second orientation.

[0011] FIG. 3 is a perspective view of two multi-function scaffolds connected together end-to-end and adjusted to the same heights.

[0012] FIG. 4 is an elevation view of two multi-function scaffolds connected together end-to-end.

[0013] FIG. 5 is a perspective view of a ladder frame for the multi-function scaffold without the detachable rungs.

[0014] FIG. 6 is a perspective view of the ladder frame with the detachable rungs.

[0015] FIG. 7 is a perspective view of a detachable ladder rung.

[0016] FIG. 8 is a top view of a detachable ladder rung.

[0017] FIG. 9 is a side view of a detachable ladder rung.

[0018] FIG. 10 is a detail showing a bracket at the end of the detachable ladder rung.

[0019] FIG. 11 is a detail perspective showing the detachable ladder rung connected to the ladder frame.

[0020] FIG. 12 is a perspective view of a side rail assembly for the multi-function scaffold.

[0021] FIG. 13 is an elevation view of a side rail assembly for the multi-function scaffold.

[0022] FIG. 14 is a detail perspective showing the locking mechanism for the side rail assembly.

[0023] FIG. 15 is a detail showing the side rail assembly connected to the ladder frame.

[0024] FIG. 16 is a cross-section of a side rail for the multi-function scaffold.

[0025] FIG. 17 is a top view of a side rail for the multi-function scaffold showing a slot for a deck latch.

[0026] FIG. 18 is an elevation view of a side rail for the multi-function scaffold showing a slot for a deck latch.

[0027] FIG. 19 is perspective view showing a 2×2 wall stack composed with 4 multi-function scaffolds.

[0028] FIG. 20 is a perspective view of two multi-function scaffolds connected together end-to-end and adjusted to different heights.DETAILED DESCRIPTION

[0029] Referring now to the drawings, a multi-function scaffold 10 according to an exemplary embodiment is shown. The multi-function scaffold 10 comprises two ladder frames 12 and an adjustable height platform 40 supported between the two ladder frames 12. As will be hereinafter described, the ladder frames 12 are walk-through ladder frames with detachable rungs 30. The adjustable height platform 40 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. 1, enables the platform 40 to be adjusted to its maximum height. The second orientation, shown in FIG. 2, enables the platform 40 to be adjusted to its minimum height. The ladder frames 12 enable a worker to easily access the platform 40 at any height while meeting OSHA climb requirements.

[0030] FIGS. 3 and 4 show two scaffolds 10 connected end-to-end to form a larger scaffold. In this case, the two scaffolds 10 share a ladder frame 12 so that the combined scaffold includes three ladder frames 12 and two platforms 40. The platforms 40 of the two scaffolds 10 can be adjusted to the same height to prevent a trip hazard when moving between scaffolds 10 but may also be adjusted to different heights. This flexibility is useful, for example, when working in a stairway. The detachable rungs 30 can be removed from the shared ladder frame 12 to enable workers to easily move between adjacent platforms 40 without obstruction. The detachable rungs 30 can also be removed from one of the non-shared ladder frames 12 at the end of the combined scaffold to make access to the platforms 40 easier. FIG. 20, for example, shows two scaffolds connected together with the platforms 40 at different heights and removable rungs 30 removed at each end to allow access to each platform 40.

[0031] FIGS. 5 and 6 illustrate a walk-through ladder frame 12 with and without detachable rungs 30 respectively. The walk-through ladder frame 12 comprises two vertical supports 14 connected by one or more fixed rungs 18, two handrail assemblies 20 connected to respective ones of the vertical supports 14 on either side of the ladder frame 12, and one or more detachable rungs 30 (FIG. 6) that removably mount to the handrail assemblies 20. The vertical supports 14, fixed rungs 18 and handrail assemblies 20 of the walk-through ladder frame 12 are preferably made of a metal tubing or other tubular material welded together to form a unitary structure.

[0032] The vertical supports 14 of the ladder frame 12 include a series of spaced-apart openings 16 (e.g., 2 inch spacing) that extend through the vertical supports 14 perpendicular to the plane of the ladder frame 12. As will be hereinafter described in more detail, a releasable locking mechanism 60 on the platform 40 engages the openings 16 in the vertical supports 14 to secure the platform 40 at a desired height between the ladder frames 12. Additionally, openings 17 (FIG. 5) extend transversely through the lower end of each vertical support 14. These openings 17 are used to secure casters 90 to the vertical supports 14 (FIG. 6).

[0033] The vertical supports 14 of the ladder frame 12 also includes stacking pins 92 to enable stacking of ladder frames 12. The stacking pins 92 include one or more openings 94 that align one of the openings 16 in the vertical support 14 of a vertically stacked ladder frame 12. A span pin can be inserted through the aligned openings 16, 94 to secure the ladder frames in a stacked configuration. The use of stacking pins 92 in multi-function scaffolds is known in the art and is not

[0034] Each handrail assembly 20 includes a handrail 22 extending vertically from a fixed ladder rung 18 and one or more tie members 24 connecting the handrail 22 to a respective one of the vertical supports 14. The tie members 24 have openings 26 formed therein for securing the detachable rungs 30 as will be hereinafter described. In the illustrated embodiment, the handrail 22 extends from the uppermost fixed rung 18. In other embodiments, the handrail 22 may extend below the uppermost fixed rung 18. In this case, one or more of the fixed rungs 18 can be welded to the handrail 22 of the handrail assembly 20 to indirectly connect the fixed rungs 18 to the vertical supports 14 of the ladder frame 12.

[0035] The handrails 22 of the walk-through ladder frame 12 are spaced apart to provide an opening therebetween referred to herein as a pass-through. The pass-through is unobstructed in the vertical direction above the uppermost fixed ladder rung 18, i.e., is open at the top, so that a person can pass between the handrails 22 when the detachable rungs 30 are removed. For example, when two scaffolds 10 are joined as shown in FIGS. 3 and 4, the pass-through between the handrails 22 on the shared walk-through ladder frame 12 allows a worker to step without obstruction between the handrails 18 from the platform 40 on one scaffold 10 onto the platform 40 of on an adjacent scaffold 10. Detachable rungs 30 can also be removed from the one or more of the ladder frames 12 on the ends to make access to the platform 40 easier (FIG. 19).

[0036] FIGS. 7-10 illustrate an exemplary detachable rung 30. The detachable rung comprises a cross-member 32 having a bracket 34 at each end thereof configured to engage a respective one of the handrail assemblies 20. The bracket 32 comprises a main plate 34a and hanger 34b. The main plate 34a extends generally parallel to the plane of the ladder frame 12 and includes an inwardly turned flange 34c fixed to one end of the cross member 32. The hanger 34b extends from a top edge of the main plate 34 and includes a downwardly turned end portion that forms a hook configured for engagement with a respective tie member 24. The hanger 34b is spaced from the flange 34c creating a gap 34d between the hanger 34b and flange 34c. A gusset 34e connects the bracket 34 with the cross member 32 to provide additional strength and rigidity. Aligned openings 34f (FIG. 10) are formed in the main plate 34a and end portion of the hanger 34b. As will be hereinafter described, these openings 34f are engaged by a pin 34g (FIGS. 11 and 15) to secure the detachable rung 30 once it is mounted to the ladder frame 12.

[0037] To install the detachable rung 30, the detachable rung 30 is held in front of the ladder frame 12 with the cross member 32 level to the ground and the gaps 34d in the brackets 34 aligned with respective handrails 22 on either side of the ladder frame 12. As the detachable rung 30 is moved toward the plane of the ladder frame 12, the handrails 16 are received in the gaps 34d in the brackets 34. When the cross-member 32 is aligned with the plane of the ladder frame 12, the detachable rung 30 can be lowered so that the hangers 34b at each end engage respective tie members 24 to suspend the detachable rung 30 between the handrails 22. With the detachable rung 30 suspended, a pin 34g is inserted through the aligned openings 26, 34f in the tie member 24 and bracket 34 respectively to prevent the detachable rung 30 from disengaging (FIGS. 11 and 15).

[0038] To remove a detachable rung 30, the pins 34g securing the detachable rung 30 are removed. The detachable rung 30 can then be lifted upward to disengage the hangers 34b from the tie members 24 after which the detachable rung 30 can be moved laterally away from the ladder frame 12.

[0039] While the detachable rung 30 is the illustrated embodiment attach to the handrail assembly 20, those skilled in the art will appreciate that alternate embodiments where the detachable rungs 30 that connect to the vertical supports 14 of the ladder frame 12 are also possible.

[0040] FIGS. 12-18 illustrate elements of the adjustable platform 40. The adjustable height platform 40 comprises two side rail assemblies 42 (FIGS. 12-14) that extend between the ladder frames 12 and a deck 70 (FIG. 1) that is supported by the side rail assemblies 42. The side rail assemblies 42 are designed to slide along the vertical supports 14 of the ladder frames 12. A locking mechanism 60 locks the side rail assemblies 42 at the desired height.

[0041] Each side rail assembly 42 comprises a side rail 44 and two guide channels 50 connected at opposite ends of the side rail 44. A brace 46 extends between the side rail 44 and guide channel 50 at each end to provide strength and rigidity. The ends of each side rail 44 connect directly or indirectly to a C-shaped guide channel 50 sized to fit around the vertical supports 14 of the ladder frames 12. In some embodiments, an optional square sleeve (not shown) configured to receive a post for a safety rail is interposed between each end of the side rail 44 and the guide channel 44 for mounting a safety rail to the platform 40. The components of the side rail assembly 42 including the side rail 44, braces 46, optional sleeves, and guide channels 50 are preferably made of aluminum or other lightweight metal alloy and welded together to form a unitary structure.

[0042] FIGS. 16-18 illustrate details of the side rail 44 according to one exemplary embodiment. In this embodiment, the side rails 44 comprise elongated channels or beams extruded from aluminum or other lightweight metal or metal alloy. The side rails 44 are configured to provide a support surface for the deck 70 in two orientations, referred to herein as the first or normal orientation (FIG. 1) and the second or inverted orientation (FIG. 2).

[0043] FIG. 16 shows a cross-section of an exemplary siderail 44. In this embodiment, the side rail 44 comprises a channel having a central web 44a, inner horizontal segment 44b, vertical segments 44c, outer horizontal segments 44d, and inwardly turned lips 44e. The inner horizontal segments 44b serve as support surfaces for supporting the deck 70 in the first and second orientations respectively. The vertical segments 44c contain the deck 70 and prevent side-to-side movement. The outer horizontal segments 44d include specially formed slots 48 that are engaged by deck latches 80 as hereinafter described. The inwardly turned lips 42e increase the rigidity of the side rail 44.

[0044] The siderail 44 in the illustrated embodiment is symmetrical about an axial plane P that extends horizontally (i.e., parallel to deck 70) and divides the siderail 44 into an upper portion (above the axial plane) and a lower portion (below the axial plane). The upper and lower portions switch depending on the orientation of the siderail 44. Those skilled in the art will appreciate that other configurations of the channel are possible.

[0045] For reasons explained below, the ends of the side rail 44 on one side of the axial plane include a notch 46. The purpose of the notch 46 is to provide clearance when two side rail assemblies 42 are mounted to the same ladder frame 12 for reasons that will become apparent in the description below.

[0046] Referring back to FIGS. 12-15 the guide channels 50 comprise C-shaped channels configured to slide along vertical supports 14 of the ladder frames 12 at each end of the scaffold 10 to adjust the height of the platform 40. Each guide channel 50 comprises a central web 52 with two flanges 54. Aligned openings 56 are formed in the flanges 54 of each guide channel 50 for locking the side rail assemblies 42 at a selected height as hereinafter described. The openings 56 are spaced to align with the openings 16 in the vertical supports 14 of the ladder frame 12 at preselected heights. The openings 56 in the guide channels 50 are engaged by a releasable locking mechanism 60 (described below) on the platform 40 to secure the platform 40 at a desired height between the ladder frames 12.

[0047] The guide channels 50 connect to the side rail 44 (or to the sleeve if present) in an offset manner so that the end face 51 (FIG. 14) at the proximal end of the guide channel 50 does not extend beyond the axial plane of the siderail 44.

[0048] The offset connection enables two siderail assemblies 42 to be installed on the same vertical support 14 in opposite orientations and adjusted in height so that a first support surface 44b of the side rail 44 in a first orientation is level with a second support surface 44b of the side rail 44 in the second orientation. This feature enables the platforms 40 on two connected scaffolds to be adjusted to the same level as shown in FIGS. 3 and 4.

[0049] In one embodiment, the end face 51 of the guide channel 50 lies in the axial plane of the siderail 44. In this case, when two sideral assemblies 42 are mounted in opposite orientations on the same vertical support 14 and adjusted to the same height, the end faces 51 of the guide channels 51 abut. Alternatively, the end faces 51 can be angled relative to a vertical axis of the guide channel 50 so that a first portion of the end face 51 is below the axial plane and a second portion of the end face 51 is above the axial plane. Assuming that the geometric centers of the end faces 51 lie in the axial planes of the respective siderails 44, the angled end faces 51 would abut when two sideral assemblies 42 are mounted in opposite orientations on the same vertical support 14 and adjusted to the same height. In other embodiments, the geometric center of the end faces 51 can be offset from the axial plane so that there is a gap between the end faces 51 when two sideral assemblies 42 are mounted in opposite orientations on the same vertical support 14 and adjusted to the same height.

[0050] To strengthen the connection between the side rail 44 and guide channels 50, a gusset 55 is welded to each end of the side rail 44. The outer lip 44e along one edge of the side rail 44 includes a notch 45 where the gussets 55 attaches to the side rail 44. The gussets 55 extends beyond the side rail 44 to provide greater length for attachment to the guide channel 50 (FIGS. 12-15) . The outer edge of the gussets 55 are welded to respective guide channels 55.

[0051] As shown in FIGS. 12-15, both the gusset 55 and side rail 44 extend above the end face 51 of the guide channel 50. Because the guide channel 50 is larger than the vertical support 14 of the ladder frame, there is a natural gap 57 between the side rail 44 / gusset 55 and vertical support 14 of the ladder frame 12 when the side rail assembly 42 is mounted to the ladder frame 12 (FIG. 15). When two side rail assemblies 42 are mounted to the ladder frame 12, the gap 57 allows the guide channel 50 on one side rail assembly 42 to slide into the gap 57 in the other side rail assembly 42 so that the adjustable platforms 40 can be adjusted to the same height. The side rail 44 and gussets 55 are notched beyond the end of the guide channels 50 to provide greater clearance when two side rails 44 are mounted to the same ladder frame 12 and adjusted to the same height. Notch 46 in the side rail 44 is shown in FIG. 18. A similar notch 55a is provided in the gusset 55 (FIGS. 14 and 15).

[0052] FIG. 14 illustrates the releasable locking mechanism 60 according to an embodiment. The releasable locking mechanism 60 comprises a U-shaped latch 62 that engages with the aligned openings 56, 16 in the guide channel 50 and vertical supports 14 respectively to lock the side rail 44 at a desired height. Each latch 62 includes a pair of spaced apart legs 62a connected by a cross member 62b. The latch 62 is supported by a bracket 64 and biased to a locked position by springs 68 surrounding each leg 62a of the latch 62. The springs 68 are compressed when the latch 62 is pulled back to disengage the latch 62 and push the latch 62 back to an engaged position when the latch 16 is released.

[0053] In some embodiments, additional openings 58 are formed in the central web 52 of the guide channel 50. Openings 58 align with openings 17 in the vertical supports 14 so that, when the platform 40 is lowered, a span pin securing the casters 90 to the vertical supports 14 can be inserted.

[0054] When the side rail assemblies 42 are mounted between the ladder frames 12 and adjusted to the same height, the deck 70 can be placed between the side rails 44. As previously noted, the deck 70 rests on the supports surfaces 44b of the side rails 44. The deck 70 is held in place by latches 80 (FIG. 14) inserted into the slots 48 of the side channels 44.

[0055] Deck latches 80, also referred to as locking pins, are described in co-pending application Ser. No. 18 / 376,361 titled Deck Latch Assembly For a Scaffold Platform filed on Oct. 4, 2023 (hereinafter the '361 application), which is incorporated herein in its entirety by reference. To briefly summarize, the latch 80 includes a shaft 82 with a locking tab 84 at one end that engages the top surface of the deck 70 (FIG. 15). A spring 86 biases the latch 80 so that the locking tab 84 presses the deck 70 down against the support surface 44b of the side rail 44. The deck 70 advantageously has an edge recess 72 that receives the locking tab 84. The edge recess may advantageously be sized so that locking tab is flush with or below the top surface of the deck when received in the recess. The latch 80 is designed so that it can be inserted into the slots 48 of the side rails 44 in both orientations. When the side rail assemblies 42 are inverted, the latches 80 can be removed and re-inserted after changing the orientation of the side rail assembly 42. Reference is made to the '361 application for a more complete description of the latch.

[0056] In some embodiments, the multi-function scaffold 10 includes casters 90 or other ground-engaging members disposed at the lower ends of each vertical supports 14. The casters 90 includes stems (not shown) that extend into the vertical supports. The stem includes an opening that aligns with opening 17 in the vertical support 14 to allow insertion of a span pin to secure the caster to the vertical support 14. Because the casters 90 are not material to the disclosure, further discussion of the caster is omitted. More details regarding the casters 90 can be found in U.S. Patent Application Publication No. 1823 / 0151618 (application Ser. No. 18 / 097,349), which is incorporated herein in its entirety by reference.

[0057] The multi-function scaffold 10 as herein described can connect end-to-end with similar scaffolds 10 as well as stack vertically to form a wall unit with a larger working surface. FIG. 19 illustrates a 2×2 wall unit composed of 4 multifunction scaffolds 10. In this example, the detachable rungs 30 are removed from the center ladder frames 12 (i.e., ladder frames between connected scaffolds 10) to allow workers to move freely between the platforms 40 on the connected scaffolds 10. Additionally, the detachable rungs 30 are removed from the lower scaffold 10 on one end of the wall unit and from the upper scaffold 10 at the opposite end of the wall unit to provide easy access to both levels.

[0058] Those skilled the art will appreciate that many other configurations are possible and that the platforms on connected scaffolds can be adjusted to different heights, which is useful when working in a stairway, for example.

Claims

1. A ladder frame for a scaffold comprising:a pair of vertical supports;one or more fixed rungs extending between and connected to the vertical supports;a pair of handrail assemblies connected to and spaced inward of the vertical supports, the handrail assemblies defining a pass-through allowing a user to step through the ladder frame between the vertical supports; andone or more detachable ladder rungs configured to removably attach to the handrail assemblies.

2. The ladder frame of claim 1, wherein each of the handrail assemblies comprises:a handrail extending vertically from one of the fixed rungs, andone or more tie members extending between a respective vertical support of the ladder frame and the handrail.

3. The ladder frame of claim 2, wherein each detachable rung comprises a pair of brackets at opposite ends of the detachable rung, each bracket being configured to engage a respective handrail assembly of the ladder frame when the detachable rung is in use.

4. The ladder frame of claim 3, wherein each bracket comprises a hanger configured to engage with a respective tie member of a respective handrail assembly when the detachable rung is mounted to the ladder frame such that the detachable rung is supported by the tie member.

5. The ladder frame of claim 4, wherein the hanger comprises a main plate and a hook that extends over the respective tie member of the handrail assembly.

6. The ladder frame of claim 5, wherein each bracket further comprises an inward or outward facing channel through which a respective handrail passes when the detachable rung is mounted to the ladder frame.

7. The ladder frame of claim 6, further comprising a locking pin extending through aligned openings in the main place and hook to secure the detachable rung to the handrail assembly.

8. A scaffold comprising:first and second ladder frames, each ladder frame comprising:a pair of vertical supports;one or more fixed rungs extending between and connected to the vertical supports;a pair of handrail assemblies connected to and spaced inward of the vertical supports, the handrail assemblies defining a pass-through allowing a user to step through the ladder frame between the vertical supports; andone or more detachable ladder rungs configured to removably attach to the handrail assemblies;an adjustable height platform configured to be supported between the first and second ladder frames.

9. The scaffold of claim 8 wherein the adjustable height platform comprises:a pair of reversible side rails configured to be supported between the first and second ladder frames in a first orientation and a second orientation, each side rail including first and second support surfaces disposed on opposite sides of an axial plane dividing the side rail into upper and lower portions;a deck configured to mount between the side rails so as to be supported by the first support surfaces when the side rails are in the first orientation and by the second support surfaces when the side rails are in the second orientation; anda pair of guide channels at opposing ends of each side rail for slidably mounting the side rails to the vertical supports of the ladder frame, the guide channels being connected to the side rail in an offset manner to enable two side rails to be simultaneously mounted on the same vertical support in opposite orientations and adjusted in height so that the first support surface of the side rail in a first orientation is level with the second support surface of the side rail in the second orientation.

10. The ladder frame of claim 9, wherein each of the handrail assemblies comprises:a handrail extending vertically from one of the fixed rungs, andone or more tie members extending between a respective vertical support of the ladder frame and the handrail.

11. The ladder frame of claim 10, wherein each detachable rung comprises a pair of brackets at opposite ends of the detachable rung, each bracket being configured to engage a respective handrail assembly of the ladder frame when the detachable rung is in use.

12. The ladder frame of claim 11, wherein each bracket comprises a hanger configured to engage with a respective tie member of a respective handrail assembly when the detachable rung is mounted to the ladder frame such that the detachable rung is supported by the tie member.

13. The ladder frame of claim 12, wherein the hanger comprises a main plate and a hook that extends over the respective tie member of the handrail assembly.

14. The ladder frame of claim 13, wherein each bracket further comprises an inward or outward facing channel through which a respective handrail passes when the detachable rung is mounted to the ladder frame.

15. The ladder frame of claim 14, further comprising a locking pin extending through aligned openings in the main place and hook to secure the detachable rung to the handrail assembly.

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