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.

What is claimed is: 
     
         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; and   wherein 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; and   the 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; and   wherein 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; and   a 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.