Abstract:
A lock utilizing a retractable pin is used to capture one link of a chain to fasten the chain to one or more vertical uprights. The user depresses a bolt that protrudes from the hollow vertical stake member to overcome spring tension and slide a hardened pin away from a slot in the stake and an aligned slot in the lock housing, then inserts a selected link of a chain and releases the bolt, which slides the pin through the chain link and beyond the slots. The pin reciprocates within a tight-fitting bore in the lock housing, increasing lateral strength of the locking system. The resulting railing can cover any length and a number of spaced parallel railings can be strung between spaced vertical uprights.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
   Not Applicable. 
   STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
   Not applicable. 
   REFERENCE TO A SEQUENCE LISTING 
   Not Applicable. 
   BACKGROUND OF THE INVENTION 
   The present invention is related to an apparatus for providing a railing for a scaffold. More particularly, the present invention is related to an apparatus for providing a flexible strand railing, such as a chain, cable, webbing or the like, for a scaffold, a livestock fence, a crowd control barrier or the like. 
   Federal regulations require that a railing be provided for the outer perimeter of a scaffold that is more than 2 meters (6 ft.) high. Most scaffolding includes horizontal arms that project outwardly from a scaffold form or a wall which it includes a socket at their outer ends for receiving a vertical member, commonly a stake or post. Conventionally, lumber uprights, such as 2″×4″ timbers of appropriate length are installed into the sockets and other 2″×4″ members are horizontally disposed between the upright members and are nailed to them. In most cases, contractors would like to reuse this lumber in making railings for scaffolding installed at different job sites. In practice, however, such timbers are usually lost to other uses before they can be reused on another job site. 
   Frequently, after the scaffolding has been disassembled, transported to another job site and erection of the scaffolding has begun, the workers learn that the timbers used to form the railing are either missing or have been cut into pieces that make them unsuitable for use as railing. Then workers must leave the job site and go to a lumberyard to purchase replacement timbers. This time-consuming departure from the work of erecting a scaffolding may spell the difference between profit or loss on a particular job. 
   Efforts to develop reusable railings for scaffolds have led to several United States patents or published patent applications. For example, United States Patent Application Publication Number US 2003/0047382, disclosing an invention by Panacci and published on Mar. 13, 2003, discloses a Scaffolding Safety Apparatus and Method of Installation including a horizontal safety rail secured to vertical upright members. The horizontal safety rail may be connected to the upright members by a U-shaped hook having one end fastened into an aperture in a pinched and flattened end of the horizontal rail member and the other end fastened around the upright member. A spring-loaded U-shaped bracket urging the bracket into contact with the vertical post is used to mount the horizontal railings onto the vertical members. Because the railing could become disconnected from the vertical post, a chain can be used to secure a horizontal member by wrapping it around the member and securing it with a hook with the chain being secured to a channel bracket. This system requires that the horizontal railing members be an exact certain length in order to be connected to the vertical supports for the railing and presumably different lengths of railing would be needed for different types of scaffolds. Further, the hooks used to connect the horizontal railing members to the corresponding vertical support may become disconnected, leaving workers unprotected. U.S. Pat. No. 5,154,256, issued to Wood on Oct. 13, 1992 and involves exactly the same shortcomings. 
   Similarly, U.S. Pat. No. 6,131,698, issued to Reyland on Oct. 17, 2000, discloses a scaffold railing system that requires the horizontal rail members having an outwardly projecting pin that must be aligned with a vertical support member and that must fit into a U-shaped bracket on each of the principal scaffolding vertical support members. This system requires workers to align a number of different pieces and to assemble them, requiring substantial labor and specific exact dimensions between vertical and horizontal scaffold railing members, which may be difficult to achieve in the filed. 
   U.S. Pat. No. 6,006,862, issued to Palmer on Dec. 28, 1999, also suffers from these exact same disadvantages, as does the U.S. Pat. No. 3,752,262, issued to Helms on Aug. 14, 1973, which discloses a bracket for holding horizontal railing members. In this case, not only must the horizontal railing members be out an exact specific length, they must include a hole drilled all the way through that can be aligned with holes in the retaining brackets, a precision that may not always be easy to achieve in the field. 
   Therefore, a exists for a railing system for a scaffold that does not require horizontal members of any particular length; that can be reused readily and that has no other convenient use; that does not require working with precise tolerances for a suitable installation; and that can be easily and conveniently assembled and disassembled and stored or transported to a different job site. 
   BRIEF SUMMARY OF THE INVENTION 
   Accordingly, it is a primary object of the present invention to provide a railing system for a scaffold that does not require horizontal members of any particular length. 
   It is another object of the present invention to provide a railing system for a scaffold that can be reused readily and that has no other convenient use. 
   It is another object of the present invention to provide a railing system for a scaffold that does not require working with precise tolerances for suitable installation. 
   It is another object of the present intention to provide a railing system for a scaffold that can be easily and conveniently assembled and disassembled and stored or transported to a different job site. 
   These objects are achieved by providing a railing system that includes spaced vertical members with horizontal railing members consisting of a flexible member, such as a linked chain, a cable or webbing which one link of a linked chain is placed into a slot in each vertical number and secured in place by a hardened steel pin in a locking bolt mechanism. The locking bolt is basically a bolt having a flattened portion to accommodate the selected chain link and that carries an outwardly projecting ear that includes a forwardly projecting horizontally oriented hardened steel pin. The locking bolt is seated in a housing that allows the user to push on one end of the locking bolt to overcome a spring bias and move the locking pin rearward away from the slot in the housing. The user inserts the selected chain link into the slot and releases the locking bolt, which then slides forward so that the locking pin captures the selected chain link and slides past the slot, holding the chain link in place. Any individual link in a chain can be selected to be locked into the locking mechanism, allowing workers to quickly and easily install the railing without any measurements needed, since the chain railing can be fastened and locked into the vertical stakes at any location along its length. The locking pin reciprocates within a tight tolerance bore through the locking block, or housing that contains the locking mechanism, resulting in a lock that resists lateral forces on the pin extremely well. Lateral forces are generated by pulling on the chain railing, as when a worker or equipment falls against it. The selected and now locked chain length is readily removed from the vertical railing member by again pressing the locking bolt rearward, thereby clearing the chain link from the locking pin. 
   In another embodiment, a steel cable or cloth webbing member is gathered at periodic intervals and fastened into small loops by a crimped cable tie or the like and the outer end of the resulting loop is secured into the locking block in the vertical members as described above. 
   Because any particular link on the chain may be selected for locking into a vertical support member, the vertical support members do not need to be spaced apart at any particular intervals to use the system disclosed herein effectively. Further the vertical members, preferably made from tubular steel having a uniform square cross-section, with the locking mechanism fastened inside, have no other particular use and although the chain may have many uses it cannot substitute for a lumber in most applications and so the complete system will typically be available for future use on other job sites. 
   Other objects and advantages of the present invention will become apparent from the following description taken in connection with the accompanying drawings, wherein is set forth by way of illustration and example, the preferred embodiment of the present invention and the best mode currently known to the inventor for carrying out his invention. 

   
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING 
       FIG. 1  is an isometric view of a foundation form system and scaffolding employing a chain railing system for scaffolding according to the present invention. 
       FIG. 2  is a fragmentary isometric view of a stake or post for holding the chain railing of the chain railing system of  FIG. 1  partially cut away to show the locking block used to secure a link of the chain railing. 
       FIG. 3  is an isometric view of a locking block for use with the chain a railing system for scaffolding of  FIG. 1 . 
       FIG. 4  is an isometric exploded view of the locking block of  FIG. 3 , and also illustrating the insertion of a link of the chain railing into the locking block. 
       FIG. 5  is a partially sectional isometric view of the locking block of  FIG. 3  taken along lines  5 — 5  of  FIG. 3  showing the locking pin in the closed or locked or equilibrium position and the preparation of a link in the chain railing for insertion into the locking block. 
       FIG. 6  is a partially sectional isometric view taken along lines  6 — 6  of  FIG. 3  illustrating the insertion of a link of the chain railing into the locking block. 
       FIG. 7  is a partially sectional isometric view taken along lines  7 — 7  of  FIG. 3  illustrating the chain railing installed and locked into position in the locking block. 
       FIG. 8  is an isometric view of the chain railing system for scaffolding of  FIG. 1  showing the chain railing system of  FIG. 1  utilizing a cable railing in lieu of a chain railing. 
       FIG. 9  is a rear view of a locking block for use in the chain railing system for scaffolding of  FIG. 1  with the backing plate and locking bolt removed. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   Referring to  FIG. 1 , there is shown a chain railing system for scaffolding  10  in use on a scaffolding. A wall form  12  for pouring a concrete a wall is assembled from sections forming a rear wall form  14  having a smooth inner surface  16  and an outer or front wall form  18  also having a smooth inner surface. Appropriate reinforcing bars and the like are inserted between the wall forms  14 ,  18  and the cavity and is filled with poured concrete to form a concrete wall. In the type of wall form illustrated, vertical sections are stacked one upon the other and fastened to each other and the form is built up vertically section by section. This task is typically preformed by workers standing on the scaffold planks  20 , which are attached to the outer wall form  18  and which allow the workers to add the next higher vertical wall form sections and then to move the scaffolding up to the newly installed section, allowing the workers to install another vertical section of the wall forms. 
   Still referring to  FIG. 1 , the scaffold planks  20  are supported by the outwardly extending horizontal arms  22 ,  24 , each of which includes a proximal end  26 ,  28 , respectively, which is fastened to a side rail  30  of the wall form by a pin  32  and is further supported by a separate depending reinforcing strut  34  that is connected to each arm  22 ,  24  and butts against the vertical side rail  30 . Typically, the scaffold planks  20  are simply laid across the outwardly extending horizontal arms  22 ,  24 . A number of more or less equally spaced arms  22 ,  24  are used to cover the length of the form being built. 
   Still referring to  FIG. 1 , the outer end of the arm  22  includes a stake socket  36  for receiving and retaining an end of a vertical stake  38  and the outer end of the arm  24  includes an identical stake socket  36  for receiving and retaining an end of a vertical stake  40 . The vertical stakes  38 ,  40  are both tubular stakes having a uniform square cross-section when the sections are taken perpendicular to the longitudinal central line of the stakes. Stakes having other cross section shapes, for example circular, could also be used and the body of the locking block  68  ( FIG. 2 ), which is secured to each vertical stake  38 ,  40  preferably inside each vertical stake  38 ,  40  would have a different outer shape. The stakes  38 ,  40  may be solid, such as timbers, with cavities formed in them to receive and retain the locking block  68  in the same fashion shown in the drawings, with suitable openings to receive the chain and to expose a button end of the reciprocating lock mechanism, but the stakes  38 ,  40  are preferably the square cross section tubular stakes illustrated and are preferably steel. The locking block  68  may be fixed to an outer surface of each stake  38 ,  40  by web bands, screws or the like, but securing the locking block inside the stakes  38 ,  40  is superior because the mechanism is better protected from damage and the resulting stakes can be stacked and bundled more readily. Any number of stakes can be used along any particular wall so as to provide stakes at the intervals necessary for supporting the anticipated loads on the stakes  38 ,  40 . An upper chain railing  42  and a lower chain railing  44  are installed along the stakes  38 ,  40  and additional chain railings can be installed along the same run of scaffolding if desired, preferably generally horizontal and generally parallel to the upper and lower chain railings  42 ,  44  shown here. The chain railing  42 ,  44  may be replaced by any suitable flexible strand strung between vertical stakes, such as a cable, rope or webbing and is readily fastened to or removed from the stakes  38 ,  40 . 
   Referring to  FIG. 2 , the stake  38 , which is identical to the stake  40  and all the stakes used in the chain railing system for scaffolding  10 , includes an end cap  46  having a depending lip portion  48  about its perimeter, which seats into the matching opening  50  in the top end of the stake  38 . The end cap  46  can be inserted into and removed from the top of the stake  38  and seals out water and debris when installed, while allowing access to the interior of the stake  38  for servicing and so forth. 
   Still referring to  FIG. 2 , the chain railing  42  consists of a series of consecutive links  52  any particular desired length, and any particular desired link, such as the locking link  54 , is pulled sideways generally perpendicular to the general run of the chain  42  and is inserted into the slot  56  in the rear side wall  58  of the stake  38 , where it is captured and locked into place by a locking block  68  mechanism described below. The stakes  38 ,  40  may be arranged so that the slot  56  faces any desired direction, but usually it is best if the slots  56  face inward, that is, toward the workers standing on the scaffold planks  20 . Four machine screws  60  are inserted into four apertures  62 , which are arranged in a square pattern surrounding a large circular aperture  64 , and are screwed into matching bores in the locking block  68 , securing it into position within the stake  38 . The large circular aperture  64  provides access to the actuating bolt  66  of the locking block  68 . The locking block  68  securely holds the chain link  54  in place against the stake  38  while enabling the chain link  54  to be removed from the locking block  68  easily and without tools. 
   Referring to  FIG. 3 , the locking block  68  includes a body  70 , preferably machined from a solid block of steel, having a vertically oriented slot cut into a left-hand face  74  for receiving the locking link  54 . On the front face  76  of the locking block  68  are four threaded bores  78  for receiving the machine screws  60 , with the four threaded bores arranged in the same pattern as the apertures  62  on the stake  38 . In the center of the square pattern formed by the bores  78  is a central aperture  80  through which the actuating bolt  66  protrudes. A backing plate  82  forms the rear face of the locking block  68  and is fastened there by two screws. 
   Referring to  FIGS. 4 ,  9  the actuating bolt  66  includes a cylindrical plunger portion  84  having a flat land portion  86  cut into it on an outer face adjacent to its distal end  88 . At the distal end lies a flange portion  90  having an outwardly projecting ear portion  92  that projects outwardly away from the flat land portion  86  and which carries a perpendicularly oriented outwardly projecting cylindrical pin  94 , which is preferably a hardened steel pin, which is parallel to and spaced apart from and is adjacent to the flat land portion  86  of the cylindrical plunger portion  84 . The pin  94  is conveniently press fitted into an aperture on the ear and flange portion  90  may conveniently include an aperture that is press fitted onto a reduced diameter end portion of the bolt itself. The cylindrical pin  94  is seated in a bore  95  in the locking block  68 , which is a tightly fitting bore and which embraces the entire length of the cylindrical pin  94  when the pin  94  is in the locked, i.e., spring-loaded equilibrium position, except for the very end that is pressure fitted into the ear  92 . The actuating bolt  66  is seated within a cavity and the locking block  68  and held in place by the backing plate  82 , which is secured by the two machine screws  96  which penetrate the matching apertures  98  and go into the aligned threaded bores  99  ( FIG. 9 ) in the locking block  68 . The locking link  54  of the chain railing  42  is hooked over the cylindrical pin  94  to secure the chain  42  or the chain  44  to the stake  38  by inserting the locking link  54  through the slot  72  in the locking block  68  and removed by pulling the locking link  54  from the locking block  68 , along the directions shown by the double-headed arrow  100 . A coil compression spring  102  presses against the rear surface of the actuating ball  66  in the front surface of the backing plate  82  to urge the locking ball  66  forward, that is, toward the front face of the locking block  68 , which pushes the cylindrical pin  94  passed the front edge  104  of the slot  72 , thereby locking the locking link  54  into place and ensuring that the locking link  54  cannot be withdrawn from the locking block  68  unintentionally. The flat land  86  is designed to receive and accommodate the end  105  of the locking link  54  of the chain  42 . 
   Referring to  FIG. 5 , the actuating bolt  66  is seated in a cylindrical bore  106  for reciprocal movement in the locking block  68 , within a substantially rectangular cavity  108  cut into the locking block adjacent to the rear face  110 , which is closed by the backing plate  82 , with the cavity projecting toward the left-hand face  74  of the body  70  and designed to accommodate the ear potion  92  of the flange portion  90 . A front wall  112  in the cavity  108  serves as a stop that is engaged by the front surface of the ear portion  92  to retain the pin  94  in its equilibrium position, that is, its locked position, due to the urging of the coil compression spring  102 , as shown in  FIG. 5 . The backing plate  82  closes the locking assembly and serves as a rear stop to limit the rearward movement of the actuating bolt  66 . 
   Referring to  FIG. 6 , to release the actuating bolt  66  so that it can receive the locking link  54  of the chain railing  42 , the user presses on the button end  114  of the locking bolt  66  in the direction of the arrow  116  and compresses the coil compression spring  102  until the rear surface of the flange  90  and ear  92  portions butt against the backing plate  82 , thereby drawing the locking pin  94 , which is behind the slot  56  in the stake  38 , back from the slot  56  in the stake  38  and the aligned slot  72  in the locking block  68  and inserts the end  105  of the locking link  54  into the slots  56 ,  72 , and then releases the button end  114 , allowing the coil compression spring  102  to force the locking bolt  66  toward the front of the locking block  68 , and simultaneously thrusting the locking pin  94  through the locking link  54  of the chain railing  42  and locking it into place. The locked position is shown in  FIG. 7 . 
   Referring to  FIG. 8 , another type of line may be used in place of a chain  42 ,  44 , such as the cable  118 , which is gathered into the short loops  120  at intervals between stakes  38 ,  40 , and are held in place by the crimped cable ties  122 . Such cables are typically stronger and lighter than chains and are easier to store. Other types of railing may be used with the locking system described here. 
   While the present invention has been described in accordance with the preferred embodiments thereof, the description is for illustration only and should not be construed as limiting the scope of the invention. Various changes and modifications may be made by those skilled in the art without departing from the spirit and scope of the invention as defined by the following claims. For example, the upper chain railing  42  and the lower chain railing  44  are both attached to the vertical posts  38 ,  40  in identical fashion and any number of chain railings may be attached to the vertical stakes and any number of vertical stakes may be arranged to provide a chain railing system of any desired length. The dimensions of the locking block  68 , the slot  56  and other components may be designed to accommodate two links  54  of the a chain so that one end of each of two separate chains can be attached in a single locking block  68 , which may be particularly useful in constructing long railings. Further, a cable, rope, or webbing member is gathered at periodic intervals and small loops are formed by crimped cable ties or the like with the loops spaced closely enough together that the cable or webbing can be used with different scaffold or railing systems having different spacings between the vertical members. The locking system described herein may also be used in other applications such as roping off restricted areas, providing fencing for live stock and so forth. Further, any means for maintaining the stakes in an upright position may be used, such as driving them into the ground, anchoring them in receptacles filled with concrete, and so forth.