Abstract:
In various embodiments, an apparatus is disclosed comprising a platform, a hoisting machine mounted on the platform, and a rigging operable to raise and lower the elevator platform, said rigging passing through a fairlead, said fair lead stabilizing said elevator platform to a single location proximate a top of said elevator platform, said fairlead comprising two separable parts wherein said separable parts can be placed around said rigging without accessing an end of said rigging. Such a fairlead improves the serviceability of the equipment and reduce down time for replacement of a worn or damaged fairlead.

Description:
BACKGROUND 
     A fairlead is a device such as a ring or a block that has a guide opening, typically used to guide a rigging such as a line, rope or cable around an object, or to stop the rigging from moving laterally. The American Society of Mechanical Engineers (ASME) defines a fairlead as “the uppermost guide for the suspension wire rope.” Such a device is useful to hold lines, ropes or cables in place or prevent a rigging from snagging. A fairlead can also be used to stop a straight run of line from vibrating or rubbing on another surface. The fairlead may be a separate piece of hardware, or it could be integral with another structure. 
     Fairleads are used in a variety of applications in which riggings are used, including marine vehicles, loading devices, and various hoisting applications such as elevated platforms for building maintenance. In a hoisting application, an elevated platform or basket is typically raised or lowered using a powered hoisting device attached to the platform. The hoisting device utilizes a cable that is guided through a fairlead that stabilizes the lateral movement of the cable, thus stabilizing movement of the platform as well as preventing the cable from snagging. 
     Fairleads typically wear over time from the continuous movement and friction of the rigging against the inner edges of the fairlead, and will eventually require replacement or repair. Generally, when the fairlead needs to be replaced, where the fairlead surrounds the lines, ropes or cables, all of the lines, ropes or cables must be removed from the fairlead so that the fairlead can be removed for replacement. This can be a very time consuming and labor intensive service repair. Furthermore, removal of the lines, ropes or cables may expose the equipment to damage. What is needed is a fairlead assembly that can be easily removed and replaced without removing the lines, ropes or cables to provide access for maintenance. 
     SUMMARY 
     In various embodiments, a fairlead is disclosed that is comprised of at least two separable parts which can be installed with the lines, ropes or cables in the hoist. In one embodiment, a fairlead comprised of two pieces is disclosed. The two pieces are separable and are designed to be installed on a support member that may be further coupled to the housing of a hoisting device. The two fairlead pieces may be mating pieces. In one embodiment the piece may be identical. The two mating pieces may be mounted to a hoist fairlead support member and secured to captivate a wire or cable of a hoisting device. 
     In one embodiment, one mating piece is designed to fit to a “U” fairlead mount. When a second U-shaped piece is mated together with the first, the two U-shaped areas form an enclosed area that allows movement of a restrained cable or wire. One or more holes may be provided to allow for bolts or other fasteners to secure the two mating pieces. 
     Such a fairlead improves the serviceability of the equipment and reduces down time for replacement of a worn fairlead. Further embodiments provide added features such as a self locking capability and indication of degree of wear and are further described below. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The foregoing summary, as well as the following detailed description of preferred embodiments, is better understood when read in conjunction with the appended drawings. For the purposes of illustration, there is shown in the drawings exemplary embodiments; however, the present disclosure is not limited to the specific methods and instrumentalities disclosed. In the drawings: 
         FIG. 1  is a diagram illustrating an example apparatus in which aspects of the described embodiments may be incorporated. 
         FIG. 2  is a diagram illustrating an embodiment of a hoisting device. 
         FIG. 3  is a diagram illustrating an embodiment of a fairlead mounted on a hoist fairlead support bracket. 
         FIG. 4  is a diagram illustrating an embodiment of a fairlead disclosed herein. 
         FIG. 5  is a diagram illustrating a further view of an embodiment of a fairlead disclosed herein. 
     
    
    
     DETAILED DESCRIPTION 
     It is to be understood that the embodiments disclosed herein are not limited in application to the details of construction and the arrangement of components set forth in the following description or illustrated in the drawings. The disclosure is capable of other embodiments and of being practiced or being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. 
     The present disclosure relates to the production and service of hoisting devices used to elevate platforms or baskets typically associated with large structure service and maintenance, such at buildings, bridges, towers, and so on. In particular, the disclosure relates to a restraint device forming the fairlead of a platform or basket, in combination with a hoisting device.  FIG. 1  depicts an exemplary platform apparatus  10  for supporting at least one person. As shown in the figure, a platform  20  can be a flat surface, scaffolding, basket or cabin. The platform is of sufficient size to carry at least one worker. In some embodiments, the platform  20  can support a plurality of workers. The platform is typically coupled to at least one powered hoisting device  30  such that the platform can be elevated or lowered in the vertical dimension. The platform may be further secured with safety lines and guidelines. When maintaining or constructing structures of various kinds, a platform apparatus of this kind provides transport of personnel and materials to and from the various landings of the structure. The platform apparatus may also be used for work on various elevated areas of the structure. 
       FIG. 2  depicts an exemplary hoisting device  200  that may be used to elevate a platform or basket. A motor assembly  240  provides vertical lift control to the platform by winding cable  230  around a spool or drum. Cable  230  may be securely attached to the top of the structure to be traversed. Cable  230  is further guided at the top of the hoisting device by a restraint assembly  210 . Such a restraint assembly guides the line or cable from the spool or drum to the top of the platform by preventing the line or cable from moving laterally and otherwise prevent the line or cable from snagging. The restraint assembly also prevents the line or cable from vibrating or rubbing on other surfaces. The line or cable can be any type of line of sufficient strength and flexibility, such as a rope, chain, or metallic cable. 
     The restraint device comprises a fairlead, which is a member such as a ring or a block that has a guide opening. Such fairleads are typically a single piece that entirely surrounds the cable or rope. Thus a fairlead is normally installed during the downtime of a platform or hoisting device such that the end of the line or cable can be fed through the opening of the fairlead. 
     Fairleads typically wear or may otherwise be damaged over time as the lines or cables continuously move across the inside edges of the fairlead as the platform is raised or lowered during normal use. As can be seen from  FIG. 2 , a fairlead has an opening for the line or cable that encloses the circumference of the line or cable in order to secure the line or cable from lateral movement. However, the line or cable feeds through the opening of the fairlead. The end of the line or cable typically wraps around a spool. A typical replacement or repair of the fairlead requires that the line or cable be unwound from the hoisting device&#39;s spool in order to remove the fairlead and install a replacement. Other configurations are possible that use a configuration other than a spool but similar problems with fairlead replacement may be present. 
     In one embodiment of an aspect of the present disclosure,  FIG. 3  depicts a restraint assembly  300  that is comprised of a fairlead consisting of two pieces  301  and  302 . The two pieces are separable and are designed to be installed on a support member  304  that may be further coupled to the housing of a hoisting device. The restraint assembly  300  operates to restrain movement of a cable or wire  305  passing through an opening  306  of the restraint assembly. The cable or wire may be any type of rigging operable to elevate or lower a platform to be controlled by the hoisting device, and is typically a wire, rope or cable. Furthermore, the fairlead may comprise more than two pieces and may consist of dimensions other than that shown in the figure. Support member  304  is an exemplary embodiment, and may differ according to the type of hoisting device or platform used in the particular application. For example, in some cases a fairlead may be comprised of three separable pieces to enable secure mating to the support member. 
     In one embodiment, the fairlead pieces can be substantially identical mating pieces. As shown in  FIG. 3 , the location, captivation and orientation at the fairlead support is provided when the two halves are mated as indicated. The two identical mating pieces  301  and  302  may be mounted to a hoist fairlead support member  304  and secured to captivate the wire or cable  305 . The first half  302  is mounted under the fairlead support  303 , and the second half  301  is conceptually inverted and rotated 180 degrees with respect to the other piece to mate to the first half and form the complete fairlead mounted on the fairlead support member  304 . 
     Also shown in  FIG. 3  is an inner rim  307  on separable piece  302  that operates to substantially enclose the opening  306  when mated and form the fairlead hole through which the wire or cable  305  can freely move. An aspect of providing the fairlead pieces as identical mating pieces is that only one part type is required to provide the two piece assembly. Thus only one part needs to be fabricated and kept in inventory, reducing the costs associated with maintaining the fairlead. 
     As explained above, fairlead pieces  301  and  302  which form part of the restraint assembly  300  are separable and thus can be removed without pulling the cable or wire through the fairlead opening. Replacement of either or both pieces thus may be performed in-situ, including when the platform is under load. 
     The ability to replace the fairlead in-situ enables a hoisted platform apparatus that incorporates such a fairlead to be maintained and repaired more quickly and efficiently. One aspect is the reduction of down time for service. A typical fairlead device without the capability to be separated can take a minimum of 45 minutes to replace during routine service. Referring back to  FIG. 2 , it can be seen that in order to replace the fairlead at location  210  that surrounds the cable or wire  230 , the hoist device  200  and the attached platform  10  must typically be lowered to a resting position so that the cable or wire  230  can be disengaged from the hoisting device, allowing for the cable or wire to be unwound and the fairlead removed. 
     The separable fairlead assembly depicted in  FIG. 3  can be separated and removed without the need for disengaging the cable or wire, and can even be removed and replaced when the platform is under load. Since each fairlead piece does not completely enclose the cable or wire, removal of the fairlead only requires separation from one another and the support member. Likewise, installation of a replacement fairlead simply requires the insertion of each piece around the cable or line, and mating and securing the pieces to one another and/or the support member. 
     A further feature of the embodiment described above is that a fairlead assembly comprised of two simple components as illustrated provides for ease of manufacturability and reduction of manufacturing and maintenance costs. For example, in the case of a fairlead comprised of a single piece, the fairlead must be designed and fabricated to fit the fairlead support member  304 , provide securing means to the support member, and provide an opening  401  for the wire or cable  305 . The design of such a device as a single assembly is typically more complex and thus more costly than fabricating a mating piece  301  such as that shown in  FIG. 3 . 
       FIG. 4  further provides a more detailed illustration of the fairlead piece  301  designed to fit to a “U” shaped fairlead mount. As shown, the piece  301  includes a U-shaped opening  401 . When a second piece  301  is conceptually inverted and turned 180 degrees with respect to the other piece such that the two U-shaped areas are mated together, the two U-shaped areas  401  form an enclosed area that allows movement of a restrained cable or wire. In other embodiments, the “U” shaped area may be of differing dimensions to accommodate cables or wires of various diameters or to accommodate a plurality of wires and cables. Additionally, the open area  401  may be provided with other shapes provided that the mated pieces fully enclose the open area  401 . The apparatus described herein may be embodied to operate in conjunction with a variety of rigging and platform configurations, and the various embodiments described herein should not be seen as being limited to a particular example. Rigging systems may consist of cables of various diameters or may consist of a plurality of cables operating through a single fairlead. Furthermore, the support member  304  may vary in size and structure depending on the type of hoist device and platform used. In other embodiments a support member may not be provided and the fairlead may be attached directly to a hoist device or rigging or through other means. 
     Returning to  FIG. 4 , the mating piece  301  is shown with bolt holes  403 . Any number of holes may be provided to allow for bolts or other fasteners to secure the two pieces. However only a minimum of one bolt or fastener is typically required to keep the two pieces from separating. Referring to  FIG. 3 , support member  304  connects the fairlead support to the platform or basket. The bolt holes may be located such that the two mated fairlead pieces can be fastened together without penetrating the support member. When the fairlead assembly is mounted on the fairlead support as illustrated, penetration of the fairlead support for attachment is not required, thereby preserving the maximum strength of the fairlead support. In further embodiments, additional bolt or fastener holes may be provided to attach an optional tension holder. 
     Returning to  FIG. 4 , the mating piece  301  further comprises sleeve area  404  that fits onto a fairlead support member  304  as depicted in  FIG. 3 . The support rim  402  secures the fairlead assembly against the U-shaped portion  303  of the fairlead support member. Sleeve area  404  and support plate  402  can be shaped to fit mounting members of various designs and arrangements. For example, the support member may comprise a straight rather than a curved mounting area, in which case the sleeve area and support plate can comprise straight rather than curved features. 
     Support rim  402  is perpendicular to the surface of the separable piece and generally follows the curved outer edge. Support rim  402  operates to mate with support member  304  or curved portion  303  of the support member  304  when the two separable pieces are inverted and mated with one another. Inner column  405  is also perpendicular to the surface of the separable piece  301  and generally follows the curved outer edge of the U-shaped gap. The column  405  operates to enclose the opening area  401  on the second separable part, thus forming a generally circular opening through which a rigging can freely pass. Elevated columns  406  provide additional structural support for fitting the separable piece to the curved portion  303  of the support member  304 . 
     In an alternative embodiment, the fairlead mating pieces  301  and  302  can be self-locking and thus not require bolts or other fasteners. For example, self-locking elements can be bonded to the areas of contact between the mating pieces or to the support member  304 . Alternatively, self-locking fastener elements can be included in place of bolt or fastener holes, thus eliminating the need for additional bolts. 
       FIG. 3  further depicts an indication of degree of wear guide  309 . During normal operation of the platform the movement of the cables and wires will typically cause long term wear on the inner edges of the fairlead opening  306 . Such indicators may be provided to indicate the maximum degree of wear beyond which a replacement is required or recommended. The indicators may be imprinted and integral to structure of the separable part  301 , or can be marked using various marking methods such as ink or paint. Other types or shapes of wear indication guides may be provided to match various fairlead designs and the expected wear patterns on the fairlead. 
       FIG. 5  depicts a top-down view of a fairlead mating piece  301 . Shown are various aspects of the mating piece as described above, including fastening holes  403 , wear indicator  309 , and open area  401 . As illustrated the fastening holes may be equally spaced along the inner circumference of the separable piece. However, the number and placement of the fastening holes  403  may vary without departing from the scope of this disclosure. Similarly, the wear indicator  309  may be varied to match the size and shape of the open area  401 . 
     The various embodiments of the fairlead may be composed of appropriate materials that provide durability, resilience, abrasion resistance and strength. For example, thermoplastic polymers such as nylon and its various embodiments such as Nylatron may be used and can be fabricated using a single injection mold. In other embodiments other types of polymers can be used. However, the materials that may be used to fabricate the disclosure described herein are not limited to polymers. The present disclosure contemplates the use of various materials such as metal, plastic, or wood as may be useful for various applications and embodiments. 
     The method of use of embodiments of the present disclosure will now be discussed. As described above, fairleads typically wear or may otherwise be damaged over time as the lines or cables continuously move across the inside edges of the fairlead as the platform or basket is raised or lowered during normal use. Referring to the embodiment shown in  FIG. 2 , a fairlead has an opening for the line or cable that encloses the circumference of the line or cable in order to secure the line or cable from lateral movement. The line or cable feeds through the opening of the fairlead. The end of the line or cable typically wraps around a spool. 
     In the embodiment depicted in  FIG. 3 , the restraint assembly  300  is comprised of a fairlead consisting of two pieces  301  and  302 . In one embodiment, the fairlead pieces are substantially identical mating pieces. As shown in  FIG. 3 , the two mating pieces  301  and  302  may be mounted to a hoist fairlead support member  304  and secured to captivate the wire or cable  305 . The first half  302  is mounted under the fairlead support  303 , and the second half  301  is conceptually inverted and rotated 180 degrees with respect to the other piece to mate to the first half and form the complete fairlead mounted on the fairlead support member  304 . 
     When the fairlead requires removal, fairlead pieces  301  and  302  are separated by removing any fastening mechanisms and pulled apart. The fairlead pieces can then be removed without unwinding the cable or wire by pulling each fairlead piece through their respective opening  401  depicted in  FIG. 4 . Since each fairlead piece does not completely enclose the cable or wire, removal of the fairlead only requires separation from one another and the support member. Replacement of either or both pieces thus may be performed in-situ, including when the platform is under load. Referring to  FIG. 3 , the hoist device  200  and the attached platform  10  can be left in place and not be lowered to a resting position. The cable or wire  230  can be left in place in the hoisting device. 
     To install a replacement fairlead, two new fairlead pieces  301  and  302  can be placed around the cable or line, mated to one another and secured to one another and/or the support member. 
     Referring to  FIG. 4 , which depicts a more detailed illustration of the fairlead piece  301  designed to fit to a “U” shaped fairlead mount, a method for removing and replacing such a fairlead is described. As shown, the piece  301  includes a U-shaped opening  401 . To install the U-shaped fairlead, a first piece  301  is conceptually inverted and turned 180 degrees with respect to a second piece  302  such that the two U-shaped areas are mated together and the two U-shaped areas  401  form an enclosed area that allows movement of a restrained cable or wire. 
     As described above, in various embodiments the “U” shaped area may be of differing dimensions to accommodate cables or wires of various diameters or to accommodate a plurality of wires and cables. Additionally, the open area  401  may be provided with other shapes provided that the mated pieces fully enclose the open area  401 . The methods described herein may be embodied to operate in conjunction with a variety of rigging and platform configurations, and the various embodiments described herein should not be seen as being limited to a particular example. Rigging systems may consist of cables of various diameters or may consist of a plurality of cables operating through a single fairlead. Furthermore, the support member  304  may vary in size and structure depending on the type of hoist device and platform used. In other embodiments a support member may not be provided and the fairlead may be attached directly to a hoist device or rigging or through other means. 
     Returning to  FIG. 4 , the mating piece  301  is shown with bolt holes  403 . Any number of holes may be provided to allow for bolts or other fasteners to secure the two pieces. However only a minimum of one bolt or fastener is typically required to keep the two pieces from separating. When removing a fairlead assembly for repair or replacement, the bolt or fastener is removed to enable the unmating and removal of the fairlead pieces  301  and  302 . In an embodiment whereby the fairlead mating pieces  301  and  302  are self-locking, removal of bolts or other fasteners may not be required. 
     It will be understood that each of the elements described above, or two or more together may also find a useful application in other types of methods differing from the type described above. Although the more detailed examples provided above relate to elevated platforms for building maintenance, it should be apparent to one of ordinary skill in the art that the apparatus and methods described herein will find application to other systems that utilize fairlead mechanisms. Additionally, the foregoing description has set forth various embodiments of the apparatus and methods via the use of diagrams and examples. While the present disclosure has been described in connection with the preferred embodiments of the various figures, it is to be understood that other similar embodiments may be used or modifications and additions may be made to the described embodiment for performing the same function of the present disclosure without deviating there from. Furthermore, it should be emphasized that a variety of applications, including marine and transportation systems, are herein contemplated. Therefore, the present disclosure should not be limited to any single embodiment, but rather construed in breadth and scope in accordance with the appended claims. Additional features of this disclosure are set forth in the following claims.