Compactly Stackable Scaffold Ladder Frames

Abstract

A scaffold includes first and second ladder frames. Each ladder frame includes a first and second vertical supports, a center support, rung(s), and upper and lower horizontal supports. The upper horizontal support is formed of tubular material, and has a central section and flattened end sections mounted to corresponding vertical supports. The center support and/or rungs advantageously have coped and slightly flattened end sections. Recesses formed by the flattened end sections provide space to partially receive vertical or horizontal supports of another ladder frame when the frames are stacked, thereby reducing overall stack height.

Description

TECHNICAL FIELD

The present disclosure relates generally to crimping tool for flattening the end of a pipe, and to a pipe with a flattened end formed by the crimping, and to a scaffold ladder frame that employs the pipe, and to related scaffolds and methods.

BACKGROUND

Scaffolds are commonly used in painting and other construction jobs, and traditionally allow a deck to be mounted at a desired elevation. A typical scaffold comprises two spaced-apart ladder frames connected by cross braces to form a self-supporting structure. Each ladder frame comprises two or more vertical posts interconnected by horizontal members that are welded to the vertical posts. It is known to flatten the ends of the horizontal members to facilitate stacking of the scaffold ladder frames when not in use. When the frames are vertically stacked, the vertical post on one ladder frame rests on the flattened ends of the horizontal members on the ladder frame immediately below to enable more compact stacking. See, for example, U.S. Patent Application Publication 2009/0236181.

While flattening the ends of the horizontal members facilitates stacking of the frames, the flattened ends tends to flare in both upward and downward directions. When a walkboard (or “platform”) is laid on top of the horizontal member, one edge of the walkboard is lifted slightly due to the flaring at the ends of the horizontal member. Thus, the wallboard cannot lie flat on the horizontal members.

In addition, the ladder frames typically include some intermediate horizontal members, typically on one lateral half of the ladder frame, that act as ladder rungs. Flattening the ends of these ladder rungs to the same extent as the main horizontal members, while facilitating stacking, may result in relatively weaker weld joints.

As such, there remains a need for alternative approaches to forming scaffolds and/or scaffold ladder frames, preferably approaches that advantageously allow for better accommodation of the walkboard and/or that provide enhanced weld strength while allowing for space consumption for stacking.

SUMMARY

The present disclosure is generally directed to a scaffolding and related products, tools, and methods that employ or help form flattened sections that allow for smaller stacking space to be consumed while advantageously allowing for welded joints to retain sufficient strength. Recesses formed by the flattened end sections provide space to at least partially receive vertical or horizontal supports of another ladder frame when the frames are stacked, thereby reducing overall stack height.

In one aspect, a scaffold ladder frame is disclosed. The scaffold ladder frame includes first and second vertical supports, upper and lower horizontal supports, a center support, and at least one rung. The upper and lower horizontal supports are formed of tubular material. The upper horizontal support has a central section and narrowed end sections, with the end sections mounted to corresponding vertical supports. At least the upper horizontal support is formed of a first size tubular material. The end sections of the first horizontal support include a generally flat terminal section having a first width. The center support is mounted to the upper and lower horizontal supports between the vertical supports. The center support is formed of a second size tubular material, the second size smaller than the first size and larger than the first width. The end portion of the center support proximate the upper horizontal support is narrowed to have a second width matching the first width. The rung(s) rung are mounted to the first vertical support and the center support in spaced relation to upper horizontal support. The rung is formed of second size tubular material. The end portion of the rung proximate the first vertical support is narrowed to have a second width matching the first width. In some embodiments, the central section has a circular cross-section, and the end portion of the center support proximate the upper horizontal support is both coped and narrowed.

In another aspect, a scaffold is disclosed. The scaffold comprises first and second ladder frames, and a plurality of cross braces, with each cross brace configured to be releasably connected to both the first and second ladder frames to form a self-supporting scaffold. Each ladder frame includes a pair of vertical supports, upper and lower horizontal supports, a center support, and at least one rung. The upper and lower horizontal supports are formed of tubular material. The upper horizontal support has a central section and narrowed end sections, with the end sections mounted to corresponding vertical supports. At least the upper horizontal support is formed of a first size tubular material. The end sections of the upper horizontal support include a generally flat terminal section having a first width. The center support is mounted to the upper and lower horizontal supports between the vertical supports. The center support is formed of a second size tubular material, the second size smaller than the first size and larger than the first width. An end portion of the center support proximate the upper horizontal support is narrowed to have a second width matching the first width. The rung(s) are mounted to one of the first support and the center support in spaced relation to upper horizontal support. The rung is formed of second size tubular material. An end portion of the rung proximate the first vertical support is narrowed to have a second width matching the first width. In some embodiments, the end portion of the center support proximate the upper horizontal support is both coped and narrowed.

In another aspect, a stack of scaffold ladder frames is disclosed. The stack includes a first ladder frame and a second ladder frame stacked adjacent to the first ladder frame. Each ladder frame is laid flat and includes first and second vertical supports; upper and lower horizontal supports, upper and lower horizontal supports, a center support, and at least one rung. Each upper horizontal support has a central section and narrowed end sections, with the end sections mounted to corresponding vertical supports. The center support is mounted to the upper and lower horizontal supports between the vertical supports. An end portion of the center support proximate the upper horizontal support is narrowed. The rung is mounted to the first vertical support and the center support in spaced relation to the upper horizontal support. An end portion of the rung proximate the first vertical support is narrowed. The narrowed end section of the upper horizontal support forms a first recess; and the narrowed end portion of the rung forms a second recess; and the narrowed end portion of the center support forms a third recess. The second ladder frame is oriented like the first ladder frame, and staggered in two mutually orthogonal directions relative to the first ladder frame such that: the first vertical support of the second ladder frame is partially disposed in the first and second recesses of the first ladder frame; and the upper horizontal support of the second ladder frame is partially disposed in the third recess of the first ladder frame. A combined stack height of the first and second ladder frames is less than twice a diameter of the vertical supports. In some embodiments, the horizontal supports and the vertical supports are made from tubing that is larger in cross-section than the rung and the center support, and the first recess is deeper than the second and third recesses. In some embodiments, the stack includes a third ladder frame, with the first, second, and third ladder frames being substantially identical. The third ladder frame stacked adjacent the second ladder frame and is oriented like the first ladder frame. The third ladder frame is staggered in two mutually orthogonal directions relative to the second ladder frame such that: the first vertical support of the second ladder frame is partially disposed in the first and second recesses of the third ladder frame; the upper horizontal support of the second ladder frame is partially disposed in the third recess of the third ladder frame. A combined stack height of the first, second, and third ladder frames is less than three times a diameter of the vertical supports.

In another aspect, a stack of scaffold ladder frames is disclosed. The scaffold ladder frames are as described herein. The stack includes first and second ladder frames, with the second ladder frame stacked on top of the first ladder frame. In the stack, the upper horizontal support of the second ladder frame rests in a recess formed in the center support of the first ladder frame at the narrowed end portion of that center support. The vertical support of the second ladder frame rests in a recess formed in the upper horizontal support of the first ladder frame at the narrowed end section of that horizontal support. The combined stack height of the first and second ladder frames is less than twice a diameter of the vertical supports. In some embodiments, the first and second ladder frames are similarly oriented, with the second ladder frame staggered in two mutually orthogonal directions relative to the first ladder frame.

Related methods, components, and combinations are also disclosed.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 shows a front view of a ladder frame of a scaffold of FIG. 12, with alternative placement of latch posts.

FIG. 2 shows a top view of the ladder frame of FIG. 1.

FIG. 3 shows a partial detail view of area A in FIG. 1.

FIG. 4 shows a partial detail view of area C in FIG. 2.

FIG. 5 shows a partial detail view of area Din FIG. 1.

FIG. 6 shows a partial detail view of area E in FIG. 1.

FIG. 7 shows a top view of a rung of the ladder frame of FIG. 1.

FIG. 8 shows an end view of a horizontal support for the ladder frame of FIG. 1.

FIG. 9 shows a joint between a top horizontal support and a vertical support for the ladder frame of FIG. 1.

FIG. 10A shows a view from above of a stack of a plurality of scaffold ladder frames.

FIG. 10B shows a side view of the stack of FIG. 10A, with the tops of the ladder frames facing the viewer.

FIG. 100 shows a partial sectional view of the stack at 10C-10C of FIG. 10A, near the center support, with flattening of the ends of the center support exaggerated for illustrative purposes.

FIG. 11 shows a tool for forming a flattened end of a horizontal support, and a portion of the horizontal support so formed.

FIG. 12 is a perspective view of the scaffold with two ladder frames, with an optional walkboard omitted.

FIG. 13 and FIG. 14 show an exemplary latch post for connecting the cross brace to the vertical supports of the ladder frame.

FIG. 15 shows a simplified flow diagram of a process of making a pipe with a flattened end.

FIG. 16 shows a partial detail view of area F in FIG. 1.

FIG. 17 shows a partial detail view of area G in FIG. 1.

FIG. 18 shows a side view of a center support of FIG. 1, with flattening of the ends of the center support exaggerated for illustrative purposes.

DETAILED DESCRIPTION

FIG. 12 illustrates a scaffold 10 according to an exemplary embodiment. The scaffold 10 comprises two spaced apart ladder frames 12 interconnected by removable cross braces 14 to form a rectangular scaffold 10. As will be hereinafter described, the scaffold 10 is designed to be broken down and stored in a compact space to reduce the volume occupied by the disassembled scaffold 10.

Each ladder frame 12 of the scaffold 10 comprises vertical supports 20, horizontal supports 30, an optional center support 25, and one or more optional ladder rungs 50 extending between one of the vertical supports 20 and the center support 25 to form a ladder for climbing the scaffold 10. See, e.g., FIG. 1. The vertical supports 20, horizontal supports 30, center support 25, and ladder rungs 50 are optionally all formed from metal tubular material. The cross-section of the tube is advantageously generally elliptical, with elliptical meaning oval, circular, or other generally round shape, which does not require a mathematically precise elliptical shape. In some embodiments, the generally elliptical cross-sections of the vertical supports 20, horizontal supports 30, center support 25, and/or ladder rungs 50 are circular. The cross braces 14 may comprise circular metal tubing with flattened ends where the cross braces 14 connect with the frames 12. The flattened ends may have openings formed therein that engage with inwardly projecting latch posts 100 on the vertical supports 20 of the ladder frames 12. Note that the latch posts 100 in FIG. 12 are shown in an alternative location compared with the latch posts 100 of FIG. 1; any suitable location may be used for the latch posts 100 based on desired stability, ease of manufacturing, or other considerations.

The vertical supports 20 each extend along a respective longitudinal axis 21 that is vertically oriented. The vertical supports 20 have latch posts 100 mounted thereto at appropriate locations, for mating with the cross braces 14 as discussed above. The vertical supports 20 optionally also include additional features, such as for receiving optional wheels, which are omitted from discussion herein in the interest of clarity.

The horizontal supports 30 each extend along a respective longitudinal axis 31 that is horizontally oriented. The horizontal supports 30 include a base or central section disposed between the end sections 40. As mentioned above, the horizontal supports are formed from metal tubing, which may have an elliptical cross-section. The central section 35 of the horizontal supports 30 has an upper or top centerline 36 on the upper surface parallel with the longitudinal axis 31, and a lower or bottom centerline 37 on the lower surface parallel with the longitudinal axis 31. Note that the longitudinal axis 31 is at the geometric center of the cross-section. Typically, there are two horizontal supports one upper and one lower, but there may be other numbers of horizontal supports 30.

The respective end portions 40 of the horizontal supports 30 have flattened sections 42. The flattened sections 42 have a reduced dimension (width W) when viewed from above relative to the central section, see FIG. 2 and FIG. 4. Each flattened section 42 includes a relatively flat terminal section 44, and a transition section 46. The flat terminal section 44 has an elongated (e.g., oval) cross-section, and is the portion of the horizontal support 30 mounted to the vertical support 20. The terminal section 44 is advantageously formed by crimping the end of the tube forming the vertical support 20. The crimping is advantageously such that there remains a gap between the “sides” of the crimped section. That is, the terminal section 44 advantageously remains hollow. This shape aids in forming a good weld joint when the terminal section 44 is welded to the vertical support 20. It is intended that the terminal section 44 have a longitudinal length that is sufficient to properly receive a vertical support 20 of another ladder frame 12 when the ladder frames 12 are stacked. See FIG. 10B. The transition section is disposed 46 between the terminal section 44 and the central section 35, and has a width that gradually narrows from the width of the central section 35 to the width W of the terminal section 44. The narrowing of the terminal section 44 forms a pair of recesses 48 that have a depth 48d. It should be noted that the terminal section 44 is disposed asymmetrically about the longitudinal axis of the horizontal support 30. In particular, the top T of the terminal section 44 aligns with the top centerline 36 of the central section 35, but the bottom B of the terminal section 44 is disposed so that the bottom B of the terminal section 44 extends below the bottom centerline 37 of the central section 35. Thus, the flattened terminal section 44 extends downward from the central section 35, but does not extend upward from the terminal section 44. As such, the upper surface of the horizontal support 30 is at a consistent elevation, allowing a walkboard 16 placed thereon to rest firmly on the horizontal support 30 without being lifted off the horizontal support 30 near the joint of the horizontal support 30 to the vertical support 20. See FIG. 9. Accordingly, the corners of the walkboard 16 can “rest flat” on the horizontal support 30.

The optional center support 25 is disposed generally parallel to the vertical supports 20 in spaced relation to the vertical supports 20. The center support is advantageously mounted at its upper and lower ends to the horizontal supports 30.

As mentioned above, the ladder frame 12 advantageously includes one or more ladder rungs 50 that are mounted to center support 25 and one of the vertical supports 20, so as to be generally parallel to horizontal support 30 and spaced therefrom. The tubing of the ladder rung 50 extends along a corresponding longitudinal axis 51. In order to facilitate solid connections to the center support 25 and the vertical support 20, the ladder rung 50 is advantageously tube coped on each end 52 to mate up with the corresponding vertical element. The ladder rung 50 is welded on one end 52 to the center support 25 and on the other end to the vertical support 20. In some embodiments, the ladder rungs 50 are made of the same size tubing as the horizontal supports 30, and optionally include asymmetrically flattened terminal sections on their ends to aid in stacking ladder frames 12 in offset arrangement as shown in FIGS. 10A-C. However, the ladder rungs 50 may optionally be made from tubing that is smaller than the tubing forming the horizontal supports 30 and vertical supports 20. When the ladder rung 50 is made from smaller tubing, some space is provided for stacking another ladder frame 12 in offset arrangement as shown in FIG. 100. However, if the size of the tubing for the ladder rung 50 is larger than the thickness of the terminal section 44 of the horizontal support 30, the ladder rung 50 may cause the stacked ladder frames 12 to be vertically offset more than necessary when stacked because the vertical support 20 of the other ladder frame 12 may rest on the ladder rung 50 rather than on the terminal section 44. As such, some embodiments of the ladder frame 12 employ ladder rungs 50 that have one or both of their coped ends 52 slightly flattened. That is, the ends 52 are both coped and slightly flattened, in either order but advantageously coped and then slightly flattened. For example, if the thickness of the terminal section 44 is 22.2 mm, and the ladder rung 50 is formed of 25.4 mm diameter tubing, the coped end portions of the ladder rung 50 may be slightly flattened (e.g., by crimping) so that the slightly flattened end portion 52 mounted to the vertical support 20 (and optionally both ends 52 to facilitate manufacture) has a front-to-back width (into the page thickness for the FIG. 1 view) of 22.2 mm or less. The narrowing of the ends 52 forms a pair of recesses 58 that have a depth 58d. Note that depth 58d can advantageously be less than depth 48d when the ladder rungs 50 are made from tubing that is smaller than the tubing forming the horizontal supports 30 and vertical supports 20. With such embodiment(s), the vertical support 20 of the other (“top”) ladder frame 12 may rest on both the ladder rung and the terminal section(s) 44 of the (“bottom”) ladder frame 12 when stacked. Thus, the vertical support 20 is at least partially disposed in recess 58. This allows for minimal height to be consumed by the stacked ladder frames 12.

In some embodiments, the ladder frame 12 does not include an center support and the ladder rungs 50 are mounted to a vertical support 20 on each end. Thus, the ladder rungs 50 are approximately as long as the horizontal supports 30 and reach from the vertical support 20 on one lateral side of the ladder frame 12 (for the orientation shown in FIG. 1) to the vertical support 20 on the other lateral side of the ladder frame 20.

In an exemplary embodiment, the vertical supports 20 and horizontal supports 30 can be formed of 41.3 mm diameter steel pipe. The vertical supports 20 may be about 1524 mm long and spaced about 1524 mm apart. The center support 25 may be formed of 25.4 mm diameter steel pipe, with 41.3 mm coping on each end. The ladder rungs 50 may be formed of 25.4 mm diameter steel pipe, with 25.4 mm coping on one end and 41.3 mm coping on the other end. The end 52 of rung 50 with 41.3 mm coping, or both ends 52, may be slightly flattened to a thickness of about 22.2 mm. The upper horizontal support 30 may be placed so that the upper surface of the horizontal support 30 is about 9.8 mm down from the upper end of the vertical supports 20, and the lower horizontal support 30 may be located about 1143 mm from the upper horizontal support 30. The width (front to back thickness for the orientation of FIG. 1) of the terminal section 44 may be about 22.2 mm, and the terminal section 44 may be about 50 to 55 mm long in a direction parallel to longitudinal axis 31. The terminal section 44 may have a height (distance between top T and bottom B) of approximately 52 mm. Thus, by way of example, the ratio of height to width for the terminal section 44 may be approximately 2.5:1. In other embodiments, the width of the terminal section 44 may be about 16 mm, and the terminal section 44 may be about 50 to 55 mm long in a direction parallel to longitudinal axis 31. The terminal section 44 may have a height (distance between top T and bottom B) of approximately 56 mm. Thus, by way of example, the ratio of height to width for the terminal section 44 may be approximately 3.5:1. In other embodiments, the ratio of the height to width of the terminal section 44 may be between approximately 3.5:1 and approximately 1.8:1.

FIGS. 13-14 show an exemplary latch post 100. The latch post 100 includes a slot 102 to receive a locking member 104. The locking member 104 is secured in the slot 102 by a pivot pin 106 disposed at the outer end of the latch post 100. A second pin 108 is received in a slot 110 in the locking member 104. This arrangement allows the locking member 104 to drop down under the force of gravity and thus serve as a latch as to retain the cross brace 14 on the latch post 100. During assembly of the scaffold 10, the cross braces 14 engage with the latch posts 100 on the ladder frames 12 of the scaffold. The cross braces 14 optionally have flattened ends with openings formed therein. The openings in the ends of the cross braces 14 will pass over the latch posts 100 and push the locking member 104 upwardly. Once the opening in the cross brace 14 passes over the locking member 104, the locking member 104 will drop down under the force of gravity to latch the cross brace 14 and prevent it from disengaging. In some embodiments, the cross braces 14 may be unitary, and optionally pivotably connected together. However, in order to facilitate compact storage, the cross braces 14 may advantageously be telescoping and/or composed of multiple segments releasably connected in series.

The end section(s) 40,52 of the horizontal support(s) 30 and/or the rungs 50 may be formed by crimping the end section(s) 40,52 with a suitable die tool. An example of a suitable tool for forming the end section 40 of the horizontal support 30 is shown in FIG. 11. The tool includes a first die half 82 and a second die half 84 that jointly form a die 80. Each of the die halves 82,84 have cavities 86 therein which are designed to receive the end of a tubular pipe section 90 from which the horizontal support 30 is formed. Conceptually, the tubular pipe section 90 has a base section 92 which remains undeformed in the crimping process, and an end portion 94. The cavities 86 of the first and second die halves 82,84 have a first section 87 and a second section 88. The first section 87 is shaped to conform to the base section 92 of the tubular pipe section 90. The second section 88 is shaped to asymmetrically flatten the end portion 94 to have an elongated cross-section relative to the base section 92. The deformation is such that the material of the tubular pipe section 90 is preferentially displaced, laterally in FIG. 11, in one direction over an opposing direction. The resulting elongated cross-section is such that a top T of the flattened end aligns with a top centerline 36 of the base section 92 and a bottom B of the flattened end extends below a bottom centerline 37 of the base section 92. If desired, the die 80 can be mounted to a die shoe on spacer blocks, and can be mounted by bolting, welding, or any other means known in the art. The use of the die 80 allows the crimping process to flatten the tubular material inserted therein in a consistent manner.

Referring to FIG. 15, a process (200) for forming a pipe 90 with an asymmetric flattened end portion 94 includes inserting (210) a tubular pipe section 90 into a crimping die 80, with tubular pipe section 90 having an undeformed base section 92 and an end portion 94. The process also includes compressing (220) the end portion 94 to form an asymmetrically flattened end with an elongated cross-section compared to the base section 92 such that a top T of the flattened ends aligns with a top centerline 36 of the base section 92 and a bottom B of the flattened end extends below a bottom centerline 37 of the base section 92.

The formed horizontal support 30 is an example of a pipe for use in scaffolding. Such a pipe 90 includes a tubular section with central section 35 and an asymmetric flattened end having an elongated cross-section. A top T of the end section aligns with a top centerline 36 of the central section 35. and a bottom B of the end section extends below a bottom centerline 37 of the central section 35.

The presence of the flattened terminal sections 44 on the horizontal support 30 allows a plurality of ladder frames 12 to be stacked in a slightly staggered arrangement (see FIGS. 10A-C) while consuming less vertical space. This is because the vertical support 20 of one ladder frame 12 rests partially in a recessed area 48 formed by the terminal section 44 of the ladder frame 12 below it, and partially in a recessed area 48 formed by the terminal section 44 of the ladder frame 12 above it. Thus, a stack 18 of N ladder frames 12 has a height that is less than N times the “height” of the vertical supports 20 (measured normal to the longitudinal axis 21, e.g., diameter). In addition, having the flattened terminal sections 44 asymmetrically disposed relative to the longitudinal axis 31 of the horizontal support 30 allows the “hump” formed by the deformed material forming the terminal section 44 to be located on one side, e.g., the lower side, of the horizontal support 30, thereby avoiding having the walkboard 16 rest on the humps. Separately, or in addition, the optional slight flattening of one or both lateral ends 52 of the rungs 50 advantageously helps prevent the rungs 50 from adding to the height of the stack 18 of ladder frames 12 (by effectively reducing their “height” in the area where the vertical support 20 of another ladder frame 12 will be resting), and/or provides a good configuration for welding.

In some embodiments, the center support 25 may optionally also have coped end portions 27 that are slightly crimped, similar to the lateral ends 52 of ladder rungs 50 discussed above. The tubing of the center support 25 extends along a corresponding longitudinal axis 26. In order to facilitate solid connections to the horizontal supports 30, the center support 25 may be advantageously tube coped on each end 27 to mate up with the corresponding horizontal support 30. The center support 25 is welded on one end 27 to the upper horizontal support 30 and on the other end 27 to the lower horizontal support 30. The center support 25 may optionally be made from tubing that is smaller than the tubing forming the horizontal supports 30 and vertical supports 20, which may optionally be of the same size as the rungs 50. When the center support 25 is made from smaller tubing, some space is provided for stacking another ladder frame 12 in offset arrangement as shown in FIGS. 10A-C. However, if the size of the tubing for the center support 25 is, along its entire length, larger than the width W of the terminal section 44 of the horizontal support 30, the center support 25 may cause the stacked ladder frames 12 to be vertically offset more than necessary when stacked because the horizontal support 30 of the other ladder frame 12 may rest on the center support 25. As such, some embodiments of the ladder frame 12 employ center support 25 that have one or both of their coped ends 27 slightly flattened. See FIGS. 100 and 18, where the slight flattening of the end 27 is exaggerated to illustrative purposes. The ends 27 are both coped and slightly flattened, in either order but advantageously coped and then slightly flattened. For example, if the thickness of the terminal section 44 is 22.2 mm, and the center support 25 is formed of 25.4 mm diameter tubing, the coped end portions 27 of the center support 25 may be slightly flattened (e.g., by crimping) so that the slightly flattened end portion 27 mounted to the horizontal support 30 (and optionally both ends 52 to facilitate manufacture) has a front-to-back width (into the page thickness for the FIG. 1 view) of 22.2 mm or less. Note that the slight flattening may be symmetric relative to axis 26, or may be asymmetric, and may use a process similar to that discussed above with respect to the ladder rungs 50. The narrowing of the ends 27 forms a pair of recesses 28 that have a depth 28d. Note that depth 28d can advantageously be less than depth 48d when the center support 25 is made from tubing that is smaller than the tubing forming the horizontal supports 30 and vertical supports 20, and may optionally be approximately equal to depth 58d. With such embodiment(s), the horizontal support 30 of the other (“top”) ladder frame 12 may rest on both the center support 25 and the vertical supports 20 of the (“bottom”) ladder frame 12 when stacked. Thus, the horizontal support 30 is at least partially disposed in recess 28. This allows for minimal height to be consumed by the stacked ladder frames 12.

A stack 18 of ladder frames 12 is shown in FIGS. 10A-C. The ladder frames 12 in the stack 18 are one or more embodiments as described herein. Advantageously, the ladder frames 12 are substantially identical. As shown, the ladder frames 12 may be stacked with the ladder frames 12 in the same orientation. Thus, for example, the upper horizontal supports 30 of adjacent ladder frames 12 are closer to each other than they are to their respective lower horizontal supports 30. Within the stack 18, an upper frame 12 rests on adjacent lower frame 12, and is staggered in two mutually orthogonal directions relative to the lower frame 12 (e.g., south and west in FIG. 10A, or south and east, or north and west, etc.). The upper frame's upper horizontal support 30 disposed partially in recess 28 (associated with center support 25) of lower frame 12, and the upper frame's vertical support 20 disposed partially in the recess 48 (associated with upper horizontal support 30) of lower frame 12 and also partially in the recess 58 (associated with rung 50) of lower frame 12. And, if there is also a “top” frame 12 stacked above the upper frame 12, then the upper frame's upper horizontal support 30 is also disposed partially in recess 28 (associated with center support 25) of top frame 12, and the upper frame's vertical support 20 is also disposed partially in the recess 48 (associated with upper horizontal support 30) of top frame 12 and also partially in the recess 58 (associated with rung 50) of top frame 12. This compact stacking of the ladder frames 12 allows the stack height H to be smaller than is conventional, thereby reducing transport costs/difficulty. The stack height H of stacked ladder frames 12 is the height of the stack 18 of ladder frames 12 when the ladder frames 12 are laid flat, as measured into the page for the orientation of FIG. 1. See FIG. 10B. Note that the roles of the upper frame 12 and lower frame 12 may be reversed, and an “upper” frame 12 may act as a “lower” frame 12 with respect to a different adjacent frame 12, such as a third “top” frame 12 in the stack 18.

Note that the compact stacking of the present disclosure can be achieved with either asymmetric or symmetrically formed flattened sections 42. Also, the ability of the walkboard 16 to lay flat on the upper horizontal support 30 due to the absence of “hump” due to asymmetric flattening of the flattened end sections 42 can be achieved with or without the rungs 50 and/or center support 25 having slightly flattened ends.

As used herein, a claim requirement of “a X” means having one more X's, and a claim requirement of “a pair of X” means having two or more X's. The terms “upper” and “lower”, and “horizontal” and “vertical” are used with reference to the orientation of the ladder frame 12 as shown in FIG. 1 for purposes of clarity. A frame 12 falling within the scope of a claim here if in the orientation of FIG. 1 is also intended to be withing the scope of the claim if in any other orientation, such as inverted or rotated ninety degrees.

The present disclosure may, of course, be carried out in other specific ways than those herein set forth without departing from the scope and essential characteristics of the disclosure. The present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive, and all changes coming within the meaning and equivalency range of the appended claims are intended to be embraced therein.

Claims

1. A stack of scaffold ladder frames, comprising: a first ladder frame and a second ladder frame stacked adjacent to the first ladder frame; wherein each ladder frame comprises: first and second vertical supports;upper and lower horizontal supports; the upper horizontal support having a central section and narrowed end sections, with the end sections mounted to corresponding vertical supports;a center support mounted to the upper and lower horizontal supports between the vertical supports; wherein an end portion of the center support proximate the upper horizontal support is narrowed;at least one rung mounted to the first vertical support and the center support in spaced relation to upper horizontal support; wherein an end portion of the rung proximate the first vertical support is narrowed;wherein the narrowed end section of the upper horizontal support forms a first recess;wherein the narrowed end portion of the rung forms a second recess;wherein the narrowed end portion of the center support forms a third recess;wherein the second ladder frame is oriented like the first ladder frame, and wherein the second ladder frame is staggered in two mutually orthogonal directions relative to the first ladder frame such that: the first vertical support of the second ladder frame is partially disposed in the first and second recesses of the first ladder frame;the upper horizontal support of the second ladder frame is partially disposed in the third recess of the first ladder frame;a combined stack height of the first and second ladder frames is less than twice a diameter of the vertical supports.

2. The stack of claim 1: wherein the horizontal supports and the vertical supports are made from tubing that is larger in cross-section than the rung and the center support; andwherein the first recess is deeper than the second and third recesses.

3. The stack of claim 1: further comprising a third ladder frame; wherein the first, second, and third ladder frames are substantially identical; the third ladder frame stacked adjacent the second ladder frame;wherein the third ladder frame is oriented like the first ladder frame, and wherein the third ladder frame is staggered in two mutually orthogonal directions relative to the second ladder frame such that: the first vertical support of the second ladder frame is partially disposed in the first and second recesses of the third ladder frame;the upper horizontal support of the second ladder frame is partially disposed in the third recess of the third ladder frame;a combined stack height of the first, second, and third ladder frames is less than three times a diameter of the vertical supports.

4. The stack of claim 1, wherein, for each ladder frame: the central section has a circular cross-section; andthe end portion of the center support proximate the upper horizontal support is both coped and narrowed.

5. The stack of claim 4, wherein, for each ladder frame, the end portion of the rung is both coped and narrowed.

6. A scaffold ladder frame, comprising: first and second vertical supports;upper and lower horizontal supports formed of tubular material; the upper horizontal support having a central section and narrowed end sections, with the end sections mounted to corresponding vertical supports; wherein the upper horizontal support is formed of a first size tubular material; wherein the end sections of the upper horizontal support include a generally flat terminal section having a first width;a center support mounted to the upper and lower horizontal supports between the vertical supports; wherein the center support is formed of a second size tubular material, the second size smaller than the first size; wherein the second size is larger than the first width;wherein an end portion of the center support proximate the upper horizontal support is narrowed to have a second width matching the first width;at least one rung mounted to the first vertical support and the center support in spaced relation to upper horizontal support; wherein the rung is formed of second size tubular material; wherein an end portion of the rung proximate the first vertical support is narrowed to have a second width matching the first width.

7. The scaffold ladder frame of claim 6, wherein the central section has a circular cross-section, and wherein the end portion of the center support proximate the upper horizontal support is both coped and narrowed.

8. The scaffold ladder frame of claim 6, wherein the first width is approximately half a diameter of the one of the vertical supports.

9. The ladder frame of claim 6, wherein each end of the center support is narrowed and coped.

10. The scaffold ladder frame of claim 6: wherein the end sections of upper horizontal support are asymmetrically narrowed and have vertically elongated cross-sections compared to the central section; wherein the central section of the upper horizontal support has a top centerline and a bottom centerline;wherein a top of the end section of the upper horizontal support aligns with the top centerline of the central section; andwherein a bottom of the end section of the upper horizontal support is disposed below the bottom centerline of the central section.

11. A scaffold, comprising: first and second ladder frames, each ladder frame comprising: first and second vertical supports;upper and lower horizontal supports formed of tubular material; the upper horizontal support having a central section and narrowed end sections, with the end sections mounted to corresponding vertical supports; wherein the upper horizontal support is formed of a first size tubular material; wherein the end sections of the upper horizontal support include a generally flat terminal section having a first width;a center support mounted to the upper and lower horizontal supports between the vertical supports; wherein the center support is formed of a second size tubular material, the second size smaller than the first size; wherein the second size is larger than the first width;wherein an end portion of the center support proximate the upper horizontal support is narrowed to have a second width matching the first width;at least one rung mounted to the first vertical support and the center support in spaced relation to upper horizontal support; wherein the rung is formed of second size tubular material; wherein an end portion of the rung proximate the first vertical support is narrowed to have a second width matching the first width;a plurality of cross braces, each configured to be releasably connected to both the first and second ladder frames to form a self-supporting scaffold;

12. The scaffold of claim 11, wherein the end portion of the center support proximate the upper horizontal support is both coped and narrowed.

13. The scaffold of claim 11, wherein both ends of the center support are narrowed and coped.

14. The scaffold of claim 11, wherein the second size is about 60% of the first size.

15. The scaffold of claim 11, wherein there are at least two rungs for each ladder frame.

16. The scaffold of claim 11, further comprising a walkboard configured to be supported by the upper horizontal supports of the first and second ladder frames.

17. The scaffold of claim 11, wherein the second horizontal supports also have narrowed end sections.

18. The scaffold of claim 17, wherein the end sections of the second horizontal supports are asymmetrically flattened end sections.

19. The scaffold of claim 11, wherein, for each ladder frame: the central section of the top horizontal support has a top centerline and a bottom centerline;the narrowed end sections of the upper horizontal support are asymmetrically flattened end sections having a vertically elongated cross-section compared to the central section;a top of each end section aligns with the top centerline of the central section; anda bottom of each end section is disposed below the bottom centerline of the central section.

20. The scaffold of claim 11, wherein, for each ladder frame, the central section of the upper horizontal support has a circular cross-section.