Abstract:
An enhanced safety scaffold assembly ( 10 ) is provided including end frames ( 12,14 ) interconnected by means of cross-tie structure ( 18,20 ). The end frames ( 12,14 ) include ledgers ( 36 ) located a safety distance ( 38 ) of at least about thirty inches below the upper ends ( 26   b,   28   b ) of the standards ( 26,28 ), and are free of additional ledgers within the safety distance. A platform ( 16 ) is supported by the ledgers ( 36 ), and guardrail assemblies ( 22,24 ) extend between opposed standards ( 26,28 ). In this way, the platform ( 16 ) is located well below the upper ends ( 26   b,   28   b ) of the standards ( 26,28 ) in accordance with existing safety regulations, and placement of a platform ( 16 ) in an unsafe, elevated position is precluded. The assemblies of the invention may be constructed in a variety of ways to include optional leveling units ( 58 ), ladders ( 44 ), outriggers ( 134 ) and supplemental work platforms ( 144 ).

Description:
CROSS REFERENCE TO RELATED APPLICATION  
       [0001]     This application is being filed contemporaneously with application for U.S. Design patent Ser. No. ______, entitled SCAFFOLD FRAME SECTION WITH INTEGRAL GUARD RAIL POST, which is hereby incorporated by reference herein.  
       BACKGROUND OF THE INVENTION  
       [0002]     1. Field of the Invention  
         [0003]     The present invention is broadly concerned with improved scaffold assemblies and components thereof which are designed for enhanced user safety. More particularly, the invention is concerned with scaffold assemblies and the end frames forming a part thereof, wherein personnel platform-supporting ledgers are provided at a significant safety distance below the upper ends of the platform end frames so that a user is precluded from positioning a personnel platform at an elevated, unsafe position.  
         [0004]     2. Description of the Prior Art  
         [0005]     Scaffolding of various types has been provided in myriad forms over the years. To be effective, construction site scaffolding must be relatively easy to assemble and provide a degree of flexibility so that scaffolding of various heights and widths can be built. At the same time, such scaffolding must be sturdy and structurally sound when constructed.  
         [0006]     In recent years, safety regulations have mandated that personnel platforms forming a part of scaffolding be located below the upper ends of the scaffolding, so that appropriate guardrails can be installed and are effective. As can be appreciated, if a personnel platform is located near the very top of a scaffolding unit, workers standing on the platforms may be subjected to significant falling hazard owing to the fact that inadequate guardrails are present.  
         [0007]     While these safety standards have been in place for several years, it is still possible with existing scaffold designs to inadvertently or intentionally construct a scaffold assembly with improperly and unsafely positioned personnel platforms. This is because of the fact that prior scaffold frames have cross bars (often referred to as “ledgers”) close to or adjacent the upper end of the scaffold standards. In such a case, those constructing the scaffolding, either from expediency or lack of understanding of the safety rules, can place the platforms in unsafe elevated positions. Furthermore, during assembly of conventional scaffolding, workers are often required to stand on unguarded platforms while the next (upper) frame section and other scaffolding components are attached to the frame upon which the worker is supported.  
         [0008]     There is accordingly a need in the art for improved scaffolding which makes it essentially impossible to place personnel platforms in elevated, unsafe positions in violation of existing safety standards.  
       SUMMARY OF THE INVENTION  
       [0009]     The present invention overcomes the problems outlined above, and provides a scaffold assembly including a pair of end frames, each comprising a pair of laterally spaced apart, upright standards having opposed upper and lower ends, with a primary platform ledger extending between and interconnected with the standards. Each primary ledger is located a safety distance of at least about thirty (30) inches (more preferably from about thirty-six (36) to forty-two (42) inches) below the upper end of the corresponding standard. One or more personnel platforms span and are operatively supported by the end frame ledgers. Additionally, the end frames are free of platform ledgers within the safety distance above the primary ledger, so that no platform may be installed above the primary ledgers. In order to erect a free-standing scaffold, cross-tie structure is employed to interconnect the end frames. Finally, the overall scaffold assembly has a guardrail assembly extending between the end frames in the safety distance above the personnel platform.  
         [0010]     The scaffold assemblies of the invention may be provided in stacked relationship, i.e., two or more such assemblies may be placed one atop the other and interconnected. To this end, the scaffolds are designed for such vertical interconnection by means of connection insert pins at the upper ends of the corner standards, which telescope into the tubular ends of the standards of the scaffold assembly next above.  
         [0011]     In addition, the scaffold assemblies of the invention may be provided with auxiliary features such as leveling units, end ladders, outriggers, supplemental work platforms and quick-connectors.  
         [0012]     Another aspect of the present invention concerns scaffold end frame including a pair of laterally spaced apart, upright standards having opposed upper and lower ends. The end frame further includes a primary platform ledger extending between and being interconnected with the standards. The primary ledger is capable of supporting the end of a personnel platform. Moreover, the primary platform ledger is located a safety distance of at least about thirty (30) inches below each of the standard upper ends. The end frame is free of platform ledgers within the safety distance above the primary ledger.  
         [0013]     Other aspects and advantages of the present invention will be apparent from the following detailed description of the preferred embodiments and the accompanying drawing figures.  
     
    
     BRIEF DESCRIPTION OF THE DRAWING FIGURES  
       [0014]     A preferred embodiment of the present invention is described in detail below with reference to the attached drawing Figures, wherein:  
         [0015]      FIG. 1  is a perspective view of a scaffold assembly in accordance with the invention;  
         [0016]      FIG. 2  is a side elevational view of the scaffold assembly depicted in  FIG. 1 , shown during erection of another scaffold section atop the base scaffold assembly;  
         [0017]      FIG. 3  is a perspective view of a scaffold assembly in accordance with the invention, made up of two interconnected sections;  
         [0018]      FIG. 4  is a side elevational view of a scaffold end frame in accordance with the invention;  
         [0019]      FIG. 5  is a perspective view of another scaffold assembly in accordance with the invention, with the work scaffold assembly positioned atop a low-rise scaffold base;  
         [0020]      FIG. 6  is a perspective view of another type of scaffold end frame;  
         [0021]      FIG. 7  is a perspective view similar to that of  FIG. 6  but showing another type of scaffold end frame; and  
         [0022]      FIG. 8  is a perspective view of a multiple-tier scaffold assembly in accordance with the invention, equipped with ground-engaging outriggers and an uppermost outrigger work platform. 
     
    
       [0023]     The drawing figures do not limit the present invention to the specific embodiments disclosed and described herein. The drawings are not necessarily to scale, emphasis instead being placed upon clearly illustrating the principles of the invention.  
       DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0024]     Turning now to the drawings, the scaffold assembly  10  selected for illustration in  FIG. 1  broadly includes a pair of preconstructed end frames  12 , 14 , a personnel platform  16 , cross-tie assemblies  18 , 20 , and guardrail assemblies  22 , 24 . As shown, the assembly  10  is a free-standing unit for use on construction sites or in similar contexts.  
         [0025]     In more detail, the end frames  12 , 14  in the depicted embodiment are mirror images of each other. Thus, only the end frame  12  will be described in detail, with the understanding that the other end frame  14  is similarly constructed. Furthermore, the same reference numerals will be used to identify similar components of the end frame  12  and  14 .  
         [0026]     As perhaps best shown in  FIG. 4 , the end frame  12  preferably includes a pair of upright standards  26 , 28 , each having lower ends  26   a , 28   a  and upper ends  26   b , 28   b . In the preferred embodiment, the standards are formed of metal (e.g., steel or Aluminum) and have a circular, tubular configuration, although other suitable materials and configurations are within the ambit of the present invention. The standards  26 , 28  are preferably provided with a series of equally spaced apart accessory attachment holes  30  along the length thereof. As will be described, the attachment holes  30  removably receive connection pins so as to permit attachment of any variety of scaffolding accessories to the standard. Each standard is also preferably provided with three spaced apart inwardly projecting pin-type locks  32 , 33 , 34 . The overall end frame  12  also has a primary ledger  36  which extends between and is connected to the standards  26 , 28 . Preferably, the ledger  36  is formed of the same material as the standards  26 , 28  and similarly presents a circular tubular cross-section. The preferred ledger  36  is integrally connected to the standards  26 , 28  by suitable means, such as welding.  
         [0027]     Moreover, the ledger  36  is located a safety distance  38  below the upper ends  26   b , 28   b  of the ledgers. This safety distance  38  is at least about thirty (30) inches, and more preferably is from about thirty-six (36) to forty-two (42) inches. The ledger  36  is additionally supported by an end-mounted angular brace  40  secured to the underside of the ledger  36  and to the adjacent standard  26  at a point beneath the ledger. Similar to the standards  26 , 28  and ledger  36 , the brace  40  is preferably formed of cylindrical, tubular, metal bar. However, if desired, the ledger may alternatively be constructed in a manner similar to that disclosed in copending U.S. patent application Ser. No. 10/950,113, filed Sep. 24, 2004, entitled WALKBOARD LEDGER FOR SCAFFOLDING, published as Publication No. US 2005/0034922 A1, which is hereby incorporated by reference herein.  
         [0028]     The end frame  12  preferably also includes a ladder  44 . The ladder  44  includes first and second ladder side frames  46 , 48  as well as lateral rungs  50 . As illustrated, the lower ladder side frame  48  is secured to the underside of ledger  36  and extends downwardly therefrom, with the rungs  50  connected between the side frame  48  and standard  28 . The upper ladder side frame  46  is cantilever mounted through the medium of rungs  50  as shown, but does not extend to ledger  36 . Those ordinarily skilled in the art will appreciate that this configuration of the upper ladder side frame  46  permits the platform  16  to be positioned on the ledgers  36  within the confines of the ladder  44 . Although both end frames  12  and  14  have been shown as being provided with the ladder  44 , in many instances only one of the end frames is provided with a ladder  44  to provide vertical access to the elevated platform(s)  16 . It will also be appreciated that an angular brace is preferably not provided adjacent the standard  28 , as the ladder  44  sufficiently interconnects the ledger  36  and standard  28  to provide the desired structural reinforcement therebetween.  
         [0029]     In order to permit erection of a multiple-tier scaffold assembly, each of the standards  26 , 28  receives a reduced diameter insert pin stub section  52 , 54  extending above the associated upper ends  26   b , 28   b . The and upper ladder side frame  46  also has a reduced diameter stub  56 . The stacked frames may be otherwise secured to one another if desired.  
         [0030]     Returning to  FIG. 1 , it will be seen that each of the end frames includes a pair of screw-type leveling units  58 , each being associated with a respective one of the standards  26 , 28 . The units  58  are conventional and can be used to individually level each of the standards as required.  
         [0031]     The platform (also known as a walkboard)  16  preferably includes elongated side rails  60  as well as interconnected transverse end rails  62 . The rails  60 , 62  support a substantially flat walkway or platform panel  64  to support users of the scaffold assembly. The opposed ends of the platform  16  are provided with a pair of spaced attachment hooks  66  configured to receive the ledger  36  and thus support the platform in use. As noted previously, the lower end of the upper ladder side frames  46  are spaced slightly above the ledger  36 ; this permits lateral shifting of the platform  16  along the lengths of the ledgers  36  as necessary. The platform  16  is preferably constructed in a manner similar to that disclosed in U.S. Pat. No. 6,223,857, issued May 1, 2001, entitled SCAFFOLDING PLATFORM, which is hereby incorporated by reference herein. However, other suitable walkboard designs are within the ambit of the present invention.  
         [0032]     The cross-tie assemblies  18 , 20  each comprise a pair of crossed, angularly oriented tie bars  68 , 70  which are secured to the opposed standards  26 , 28  of the end frames  12 , 14 . As illustrated, each of the tie bars  68 , 70  has endmost apertured connectors  68   a , 70   a  which are designed to receive the pin-type locks  33 , 34  of the standards. The assemblies  18 , 20 , thus operatively interconnect the end frames  12 , 14  so as to present a free-standing scaffold. The locks  33 , 34  are conventional in design and serve to releasably lock the bars  68 , 70  to the standards  26 , 28  so as to prevent inadvertent removal after assembly.  
         [0033]     Finally, the scaffold assembly  10  includes the guardrail assemblies  22 , 24  each comprising a pair of vertically spaced apart guardrail ties  72 , 74  having apertured connection ends  72   a , 74   a . These guardrail ties are attached to the upper pin-type locks  32 , 33  on the opposed standards  26 , 28 . The guard rails  22 , 24  provide safety to the scaffold user by laterally constraining any workers on the platform  16 . The crossbar ties  68 , 70  and guardrail ties  72 , 74  are preferably tubular cylindrical metal bars.  
         [0034]     An important feature of the end frames  12 , 14 , and thus of the complete scaffold assembly  10 , is the provision of ledger  36  located at the safety distance below the upper ends  26   b , 28   b  of the standards. Moreover, there is no ledger within the safety distance, or closer to the upper ends of the standards (it will be appreciated that low-strength reinforcements could be provided within the safety distance, but these would not be capable of supporting a platform  16 ). As such, the users of scaffold assembly  10  are necessarily provided with lengths of standard above the platform  16  which permit installation of safety guardrails, and it is impossible for such users to inadvertently position a platform  16  within the safety distance. Furthermore, as shown in  FIG. 2 , during assembly of the scaffolding  10 , the user stands safely on the platform  16  as he/she stacks end frames one on top of another, all the while being safeguarded by the guardrails.  
         [0035]      FIG. 6  illustrates another side frame  76  in accordance with the invention, which is identical with the side frame  12  of  FIG. 4 , save for the fact that the ladder  44  is eliminated and an angular brace  42  is provided between the ledger  36  and standard  28 . Therefore, no extended discussion of this end frame  76  is needed, and the same reference numerals used in the description of the frame  12  are employed.  
         [0036]     A still further end frame  78  is illustrated in  FIG. 7 . This end frame is identical with the end frame  76  of  FIG. 6 , except for the provision of a modified ledger. Specifically, the end frame  78  has a ledger  36  associated with longer reinforcing struts  40   a , 42   a  which extend to points below that of the corresponding struts  40 , 42 . In addition, the ledger  36  is defined by double transoms or bars  80  that are spaced vertically apart. Short connection plates  82  extend between the ledger bars  80 , as shown. Here again, it will be seen that the safety distance  38  between upper ledger  80  and the upper ends  26   b , 28   b  of the standards is maintained. In use, the platform  16  may be affixed to either of the ledger bars  80 , but in either case the important safety distance  38  remains effective.  
         [0037]     The scaffold assemblies of the invention can be constructed in a variety of ways to meet the needs of a construction site. For example (see  FIG. 3 ), two (or more) scaffold assemblies  10 , 10   a  can be positioned one atop the other to create an overall scaffold of increased height. In  FIG. 3 , a lower assembly  10  is identical with that described previously, and the upper assembly  10   a  is supported on the assembly  10 . This involves securing the lower ends  26   a , 28   a  of the upper standards to the insert pins  52 , 54  of the lower standards. As illustrated in  FIG. 2 , an upper end frame  14   a  is positioned on end frame  14  by telescoping the insert pins  52 , 54  thereof into the lower tubular ends of the upper standards. When both of the upper end frames  12   a ,  14   a  are so positioned, cross-tie assemblies and guardrail assemblies are interconnected between the upper standards to complete the construction.  FIG. 3  also illustrates another feature of the invention, namely that the ledgers  36  are sufficient length to accommodate a pair of side-by-side platforms  16  as required.  
         [0038]      FIG. 5  shows another scaffold assembly  84  made up of a scaffold assembly  10  positioned atop a low-rise height extender section  86 . The latter is similar to the scaffold assembly  10 , but is not designed to support a platform and is used simply to create a higher overall scaffold. To this end, the section  86  includes a pair of pre-fabricated end frames  88 , 90 , each having upright standards  92 , 94  as well as uppermost cross brace  96 . The end frames  88 , 90  are interconnected by a cross-tie assemblies  98  as illustrated.  
         [0039]     Finally,  FIG. 8  depicts a two-tier scaffold assembly  100  made up of two stacked scaffold assemblies  102 , 104 . The assembly  102 , 104  is made up of end frames  106 , 108  including upright standards  110 , 112  and ledgers  114  extending between and interconnecting the standards. The ledgers  114  are located the safety distance  38  from the upper ends of the associated standards, and support a pair of platforms  116 . A cross-tie structure  118 , 120  is used to interconnect the end frames  106 , 108 , whereas guardrail assemblies  122 , 124  are secured to the standards within the safety distance. In this case, however, the end frames  106 , 108  have secondary guardrail assemblies  126  which augment the assemblies  122 , 124 . Each of the end guardrail assemblies  126  is in the form of a pair of vertically spaced apart, laterally extending rails  128 , 130  with interconnecting angular struts  132 . The end guardrail assemblies  126  are each conveniently attached to the standards  110 , 112  by connection pins, each of which is received in an opening defined in the assembly  126  and an aligned attachment hole  133  of the standard  110  or  112 .  
         [0040]     The lower assembly  102  is further supported by provision of four outriggers  134  respectively secured to each of the end frame standards. Each outrigger  134  includes an outboard vertical leg  136  together with horizontal and angular connection struts  138 , 140  secured to leg  136  and clamped to the associated end frame standard via clamps  142 .  
         [0041]     The upper scaffold assembly  104  is substantially identical with assembly  102  and thus need not be described in detail. However, it will be observed that the  104  assembly has, in lieu of the guardrail assembly  122 , a secondary platform assembly  144 . The assembly  144  includes a personnel platform  146  as well as upwardly extending, endmost standards  148 , 150  which support vertically spaced apart guardrail tie rods  152 , 154 . The assembly  144  is secured to upper scaffold assembly  104  by means of depending angular struts  156  attached to the standards  110  via connection pins  158  (again, each being received in an opening in the strut  156  and an aligned one of the attachment holes  133 ). Those ordinarily skilled in the art will appreciate that the scaffolding is particularly useful in permitting various scaffolding accessories (e.g., the secondary guardrail assemblies  126 , the secondary platform assembly  144 , pulley-type winches, etc.) to be simply and quickly attached to the standards. That is, the equally spaced apart attachment holes provide a system by which auxiliary scaffold components can be universally designed for uncomplicated association with the end frames.  
         [0042]     The preferred forms of the invention described above are to be used as illustration only, and should not be utilized in a limiting sense in interpreting the scope of the present invention. Obvious modifications to the exemplary embodiments, as hereinabove set forth, could be readily made by those skilled in the art without departing from the spirit of the present invention.  
         [0043]     The inventor hereby states his intent to rely on the Doctrine of Equivalents to determine and assess the reasonably fair scope of the present invention as pertains to any apparatus not materially departing from but outside the literal scope of the invention as set forth in the following claims.  
         [0044]     Having thus described the preferred embodiments of the invention, what is claimed as new and desired to be protected by Letters Patent includes the following: