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.
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.
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:
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.
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
In one embodiment of an aspect of the present disclosure,
In one embodiment, the fairlead pieces can be substantially identical mating pieces. As shown in
Also shown in
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
The separable fairlead assembly depicted in
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
Returning to
Returning to
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.
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
In the embodiment depicted in
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
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
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
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.
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