Ladder-based winch-powered plank scaffold

Abstract

A plank scaffold system and, more particularly, to a ladder-based vertically-adjustable plank scaffold system. The system may have a pair of ladders, a wall standoff mounted at the top of each of the ladders, a crane support mounted at the top of each of the ladders, a vertical guide bar and roller system to keep it from swinging on the cables, and a horizontal platform suspended on cables below the crane supports, the platform having a pair of cable winches mounted thereon for varying the elevation of the platform. Instead of ladders, tower scaffolds or stage towers may be used on each side to support the vertically-adjustable plank.

It is claimed: 
     
         1 . A ladder-based plank scaffold system, comprising:
 a pair of ladders;   a wall standoff mounted at the top of each of the ladders, each wall standoff having at least one horizontally oriented arm having a length sufficient to extend from a respective ladder to an adjacent vertical wall, the wall standoff further having a crane support fixed thereto including a crane arm that extends horizontally toward the adjacent vertical wall and has a cable attachment mount thereon;   a horizontal platform suspended below the crane supports on cables attached to the cable attachment mounts; and   a cable winch system operatively engaging the cables for varying the elevation of the platform.   
     
     
         2 . The system of  claim 1 , wherein the wall standoff and the crane support are integrated into one structural piece that is removable from a respective ladder. 
     
     
         3 . The system of  claim 2 , wherein each wall standoff includes two ladder rung braces spaced to rest on top of different rungs of the ladder on which the wall standoff mounts. 
     
     
         4 . The system of  claim 2 , wherein each wall standoff includes a pair of side lace plates with apertures for passage of an elongated cotter pin sized to pass through ladder rungs and lock the wall standoff to the ladder. 
     
     
         5 . The system of  claim 1 , wherein each wall standoff includes a vertical column with ladder mounting structure, and two of the horizontally oriented arms that are connected to the vertical column and extend horizontally to the adjacent vertical wall. 
     
     
         6 . The system of  claim 5 , wherein each of the horizontally oriented arms has an adjustable length. 
     
     
         7 . The system of  claim 1 , further including a pair of vertical guide bars each positioned alongside the adjacent vertical wall in line with one of the ladders, wherein the at least one horizontally oriented arm of each wall standoff is secured to a vertical guide bar, the horizontal platform including guide structure which engages and is configured to be guided along the guide bars. 
     
     
         8 . The system of  claim 1 , further including a pair of vertical guide bars each positioned alongside the adjacent vertical wall in line with one of the ladders, and also including at least one horizontal stabilizer bar extending from each of the ladders toward the adjacent vertical wall and connected to a vertical guide bar, the horizontal platform including guide structure which engages and is configured to be guided along the guide bars. 
     
     
         9 . The system of  claim 8 , wherein the guide structure includes roller assemblies each of which engages and is configured to slide or roll up and down along one of the vertical guide bars. 
     
     
         10 . The system of  claim 1 , wherein the cable winch system includes a pair of electric cable winches and a cable fall break. 
     
     
         11 . A ladder-based plank scaffold system, comprising:
 a pair of ladders;   a wall standoff mounted at the top of each of the ladders and having a length sufficient to extend from a respective ladder to an adjacent vertical wall, each wall standoff terminating at the adjacent vertical wall in two horizontally spaced apart arms for contacting the wall and stabilizing the ladder;   a crane support fixedly connected to and positioned adjacent the top of each of the ladders, each crane support having a cable attachment mount thereon;   a horizontal platform suspended below the crane supports on cables attached to the cable attachment mounts; and   a cable winch system operatively engaging the cables for varying the elevation of the platform.   
     
     
         12 . The system of  claim 11 , wherein each wall standoff is integrated into a terminal rung section of a respective ladder. 
     
     
         13 . The system of  claim 12 , wherein the terminal rung section of each ladder may pivot with respect to a remainder of the ladder, and further including support struts for fixing an angle of the terminal rung section. 
     
     
         14 . The system of  claim 11 , wherein the wall standoff and the crane support are separate and each crane support includes a lower portion that is angled with respect to a vertical upper column, the lower portion having a pair of side lace plates for each of the ladder rung braces with apertures for passage of an elongated cotter pin to lock the crane support to the ladder. 
     
     
         15 . The system of  claim 11 , wherein the wall standoff and the crane support are integrated into one structural piece that is removable from a respective ladder, and each wall standoff includes two ladder rung braces spaced to rest on top of different rungs of the ladder on which the wall standoff mounts. 
     
     
         16 . The system of  claim 11 , wherein the wall standoff and the crane support are integrated into one structural piece that is removable from a respective ladder, and each wall standoff includes a pair of side lace plates with apertures for passage of an elongated cotter pin sized to pass through ladder rungs and lock the wall standoff to the ladder. 
     
     
         17 . The system of  claim 11 , wherein each of the horizontally oriented arms has an adjustable length. 
     
     
         18 . The system of  claim 11 , further including a pair of vertical guide bars each positioned alongside the adjacent vertical wall in line with one of the ladders, and also including at least one horizontal stabilizer bar extending from each of the ladders toward the adjacent vertical wall and connected to a vertical guide bar, the horizontal platform including guide structure which engages and is configured to be guided along the guide bars. 
     
     
         19 . The system of  claim 18 , wherein the guide structure includes roller assemblies each of which engages and is configured to slide or roll up and down along one of the vertical guide bars. 
     
     
         20 . The system of  claim 11 , wherein the cable winch system includes a pair of electric cable winches and a cable fall break.