Abstract:
A retractable lifeline safety device usable as heights above the ground. The safety device is attached to the structure on which the worker is performing the task, and a lifeline such as a cable is withdrawn from the housing thereof, the end of which is attached to a belt or harness worn by the worker. The cable may be easily drawn out of the housing in response to the worker moving about normally in the appropriate work space, and the cable is automatically drawn back into the housing of the safety device as the worker draws closer thereto. However, should the worker fall, a brake mechanism within the safety device is automatically engaged by a sprocket and pawl system, stopping the worker&#39;s descent.

Description:
CROSS REFERENCE TO RELATED APPLICATION(S) 
       [0001]    This application is a Continuation Application claiming the benefit of priority of the co-pending International Patent Application No. PCT/US2007/015289, with a filing date of 10 Jul. 2007, which claims the benefit of priority of U.S. Utility Provisional Patent Application No. 60/819,676, filed 10 Jul. 2006, the entire disclosures of all Applications are expressly incorporated by reference in their entirety herein. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates generally to safety devices and methods for fall protection, and more specifically, to safety devices, in an exemplary embodiment, including retractable lifelines, operable for arresting or decelerating the rapid downward movement of a person or object after a fall. 
         [0004]    2. Technical Background 
         [0005]    Numerous conventional devices and methods, including retractable lifelines, are known to arrest the downward progress of a person or object after the initiation of a fall from a height. In such conventional retractable lifelines a person or object is secured to a predetermined point of a structure such that a risk of injury from a fall is minimized. Typically, if a fall occurs, the person or object secured to the retractable lifeline descends rapidly at the onset, thereby triggering a braking mechanism which, in turn, stops or slows the rate of fall. Further, under normal conditions the person wearing or attached to the device is able to withdraw a cord or cable from a housing thus extending the distance between the person and the secure point on the structure. In addition, the person may retract or rewind the cord or cable back onto the housing thus shortening the distance between himself and the secure point on the structure. This allows the person working to operate at varying distances from the secure point on the structure and does not limit him to a specific, static spot. 
         [0006]    In one such conventional, retractable lifeline, a spool assembly having a drum is provided within a housing about which a cord or cable is wound. The lifeline is designed to attach to a secure point on a structure at a predetermined height, the end of the cord or cable attaching to a safety harness worn by a person working at a height either above or below the structure. The drum is operable for rotational movement at a relatively slow rate of speed as the person to which the lifeline is secured causes the cord to extend and/or retract. The lifeline also typically includes a centrifugally actuated brake mechanism which generally consists of one or more pawls mounted inside the housing or on the drum such that the pawls rotate along with the drum as the strap, cord or cable is extended or retracted. The brake mechanism is operable for locking in the event of a fall. Specifically, in the event of a fall, the cord or cable stops extending or slows after the brake mechanism is actuated, thereby preventing injury. The lifeline is also typically provided with a sprocket that is mounted within the housing and is operable for ensuring that the pawls do not contact the cord during use. The sprocket is either stationary or held in frictional engagement with a separate washer or ring that is fixed to the housing, thus preventing the washer or ring from any movement. Thus, while the sprocket may move, its movement is limited to the extent of its frictional relationship to the stationary washer or ring. In addition, a spring or other suitable mechanism may be provided which is designed to continually exert a small force on the drum around which the cord or cable is wrapped in the direction of continually winding the cord or cable around the drum. This force serves to take up slack in the cord or cable when the person is moving toward the secure point on the structure, thus decreasing the distance and decreasing the amount of cord or cable needed to maintain continual connection between the person and the secure point in the structure. 
         [0007]    Disadvantageously, conventional retraceable lifelines stuffer from many shortcomings. By way of example, conventional retractable lifelines are typically formed by molding and can require numerous components, thus increasing the overall complexity and costs of manufacture. By way of another example, conventional lifelines may inadvertently lock up if the cable is withdrawn too quickly even though a fall is not occurring. By way of another example, conventional lifelines undesirably have power springs attached to the drum/spool by means of a screw, rivet, or other conventional device. This, in turn, requires that the power spring, and the overall size of the lifeline, to be large enough to accommodate a rivet or the like. By way of another example, conventional housings for lifelines are susceptible to damage from external forces due to their structural design. By way of yet another example, typical retractable lifeline devices have numerous parts/components that are exposed to high levels of potentially damaging forces. Specifically, the frictional forces holding the sprocket and spool assembly in place may cause excessive wear and strain on the other components. Ultimately, this may lead to failure of the device. Also, the pawls in known devices are subject to repetitive striking forces when the brake mechanism is activated and again when the spool is reversed and the pawls are released from the sprocket. By way of another example, known lifelines lack of any warning signal when a lockup is imminent. 
       SUMMARY OF THE INVENTION 
       [0008]    In view of the shortcomings of current retractable lifelines, a need exists for an improved retraceable lifeline. The present invention is designed to overcome the deficiencies and shortcomings of the devices described above. The present invention is designed to reduce the manufacturing costs and alleviate much of the unnecessary stress on the internal components caused by friction and striking forces. 
         [0009]    According to an exemplary embodiment, a retraceable lifeline device is provided that includes a cable wrapped about a rotatable spool which is, in turn, enclosed within a housing. One end of the cable terminates to a fastening mechanism such as a hook, eye, or the like for attaching to or securely clipping to a safety harness worn by a worker or climber or stationary attachment point. The opposed end is fixed to the spool upon which the cable is wound about. In exemplary embodiments, the housing is secured to an elevated surface or the worker (not shown), by a swivel assembly which allows the retractable line to freely rotate while maintaining engagement with the surface. 
         [0010]    Contained within the housing, a spool assembly having a spool/drum is supported by an axle. The axle is provided with a slot for receiving a portion of a power spring. A power spring assembly is mounted within the housing and contains the power spring. The inner end of the power spring terminates in an axle hook that fits securely within the slot in the axle. The exterior end of the power spring terminates in a spool hook that fits into a hook relief and a spool slot. The power spring has a band that holds the power spring together. A spring cover attaches to the spool such that the spring cover encases the power spring within the spool by conventional means. 
         [0011]    The end of the cable that attaches to the hook forms a loop by looping back on itself and being secured by at least one, but preferably two duplex ferrules. Such loop attaches to the hook and protrudes from a cushion. The opposite end of the cable is secured inside the housing to the spool by means of a cable stop. A portion of the cable, the reserve cable, is fixed to a spool drum about which the cable winds and unwinds. On the end of the reserve cable opposite to the cable stop, a clamp secures the reserve cable to the spool drum. The clamp is preferably attached to the spool drum by a clamp screw accessed from the exterior of the spool drum. The clamp screw attaches to a clamp flat. In the event of a fall in which the cable extension reaches the reserve cable, the screw, the screw hole threads, or the clamp flat breaks and allows the reserve cable to be withdrawn from the spool, thus providing additional time to slow the rate of extrusion of the cable from the spool. 
         [0012]    On the lower end of the housing where the cable exits, a cable guide separates the cable from the body of the housing and prevents the cable from rubbing against the housing while it is withdrawn and retracted. The cable guide has a cable guide tab protruding around its perimeter for engagement with the housing. The cable guide tab is held in place, or nested, within the housing by a cable guide mount. 
         [0013]    Within the spool and adjacent to the power spring are two pawls rotatably mounted on corresponding pawl axles. The pawls are held on the pawl axles by pawl washers and snap rings. The rotation of the pawls are arrested by pawl springs that attach the tip of the pawls. The pawl springs exert enough force on the ends of the pawls to keep their position stationary. Pawls stops are provided to limit the extent of the rotation of the pawls. A pair of spring guards are attached to the axle in opposite relation between the pawls such that the spring guards provide protection to the pawl springs. 
         [0014]    Inside the housing is provided at least one spring washer, a friction ring and a sprocket. On a side of the sprocket opposite the friction ring is provided at least one of washers and a pressure plate. The pressure plate is held against the washers and secured to the housing by a plurality of pressure plate screws. The pressure of the sprocket against the friction ring creates the drag friction needed to arrest the rotating spool. 
         [0015]    The sprocket has at least one tooth with a terminal end disposed at a predetermined tooth ramp angle such that the tooth protrudes slightly further toward the pawls. During normal operation of the retractable line the pawls do not engage the sprocket or contact the tooth. As the centrifugal force-begins to rotate the pawls about the axles, the tips of the pawls will contact the tooth causing all audible click. 
         [0016]    In other exemplary embodiments, the housing is strengthened by inclusion of case indents. The case indents are generally comprised of the indent web wall and the indent vertical wall. The case indents follow the contour of the spool. 
         [0017]    In all exemplary embodiments, the retractable lifeline is easier to manufacture and maintain. Further, the present invention provides an audible and tactile indicator of impending lockup by utilizing a sprocket with one or more distinct teeth. Normally, the sprocket consists of a plurality of teeth each identical and spaced so the pawls may enter into a root area thereby engaging the sprocket. The present invention alters a tooth on the sprocket to extend slightly beyond the normal teeth. A tooth ramp on the top of this odd tooth is provided at a predetermined tooth ramp angle such that as the pawls begin to rotate on the pawl axles, the end of the pawl will contact the tooth ramp and deflect off. Thus the pawl will strike the tooth ramp but not engage the root area and not engage the sprocket. The pawl contacting the tooth ramp produces an audible signal and a tactile signal which alerts the user that lockup is imminent. In the event of a fall, the velocity of the pawls is such that the pawl will enter the root area and engage the sprocket. Still further, the exemplary embodiments of the present invention provide a retractable lifeline that has power springs attached to the drum/spool by means of a band, thereby permitting a smaller size than that of conventional devices. Still further, the exemplary embodiment of the present invention provides a retractable lifeline which has a housing constructed with case indents, thereby providing a stronger and lighter device. Still further, the exemplary embodiments disclose an assembly which includes pawls that are resistant to damage via their connection to the spool assembly. 
         [0018]    Additional features and advantages of the invention will be set forth in the detailed description which follows, and in part will be readily apparent to those skilled in the art from that description or recognized by practicing the invention as described herein, including the detailed description which follows, the claims, as well as the appended drawings. 
         [0019]    It is to be understood that both the foregoing general description and the following detailed description present exemplary embodiments of the invention, and are intended to provide an overview or framework for understanding the nature and character of the invention as it is claimed. The accompanying drawings are included to provide a further understanding of the invention, and are incorporated into and constitute a part of this specification. The drawings illustrate various embodiments of the invention, and together with the detailed description, serve to explain the principles and operations thereof. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0020]    These and other features, aspects and advantages of the present invention are better understood when the following detailed description of the invention is read with reference to the accompanying drawings, in which:— 
           [0021]      FIG. 1  is an exploded perspective view of a retractable lifeline constructed in accordance with an exemplary embodiment of the present invention. 
           [0022]      FIG. 2  is an exploded perspective view of a spool assembly of the retractable lifeline of  FIG. 1  wherein the orientation of pawls is shown. 
           [0023]      FIG. 3  is a cross-sectional view of a cable guide of the retractable lifeline of  FIG. 1  showing the preferred arrangement of a cable guide mount and a cable guide tab. 
           [0024]      FIG. 4  is a perspective view of a power spring and its installation within the spool assembly of  FIG. 1 , showing a band and a band hole. 
           [0025]      FIG. 5  is a perspective view of the spool assembly showing a reserve cable. 
           [0026]      FIG. 6  is a cross-sectional view of the retractable lifeline with the housing removed. 
           [0027]      FIG. 7  is a cross-sectional view of an exemplary embodiment of the lockup indicator showing one pawl in normal operating position and one pawl in lockup position with the sprocket. 
           [0028]      FIG. 8  is a cross-sectional view of another exemplary embodiment of the lockup indicator showing one pawl in normal operating position and one pawl in lockup position with the sprocket. 
           [0029]      FIG. 9  is a perspective view of a Belleville washer used in the exemplary embodiments of the retractable lifeline of the present invention. 
           [0030]      FIG. 10  is a cross-sectional view of an exemplary embodiment of the housing of the retractable lifeline of the present invention wherein the housing is constructed with case indents. 
       
    
    
     DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS 
       [0031]    The present invention will now be described more fully hereinafter with reference to the accompanying drawings in which exemplary embodiments of the invention are shown. However, this invention may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. These exemplary embodiments are provided so that this disclosure will be both thorough and complete, and will fully convey the scope of the invention to those skilled in the art. Like reference numbers refer to like elements throughout the various drawings. Further, as used in the description herein and throughout the claims that follow, the meaning of “a”, “an”, and “the” includes plural reference unless the context clearly dictates otherwise. Also, as used in the description herein and throughout the claims that follow, the meaning of “in” includes “in” and “on” unless the context clearly dictates otherwise. 
         [0032]    In the exemplary embodiments described herein, the present invention provides a retractable lifeline safety device operable for arresting or decelerating the rapid downward movement of a person or object after a fall. The exemplary embodiments of the invention also provide a retractable lifeline that is easier and more cost efficient to manufacture and that signals a user when a lockup is about to occur. Further, the exemplary embodiments of the present invention provide a retractable lifeline warns the wearer of an impending lock up of the cable if the same is being withdrawn too quickly. Still further, the exemplary embodiments of the present invention provide a retractable lifeline that has power springs attached to the drum/spool by means of a band eliminating the need for bulky fasteners, thereby permitting a smaller size than that of conventional devices. Still further, the exemplary embodiment of the present invention provide a retractable lifeline which has a housing constructed with case indents, thereby providing a stronger and lighter device. Still further, the exemplary embodiments disclose an assembly which includes pawls that are resistant to damage via their connection to the spool assembly. 
         [0033]    Referring now to the drawings, and specifically to  FIG. 1 , there is shown an exemplary embodiment of a retractable lifeline constructed in accordance with the principles of the current invention and designated generally as  10 . The retractable lifeline device  10  is generally includes a spool assembly having a cable  12  wrapped around a rotatable spool or drum  14  which is, in turn, enclosed within a housing  16 . The housing  16  is formed by two complimentary halves,  18  and  20 , being removably joined together, the first half  18  having a spring which securely attaches to a sprocket contained within the opposed half  20 , thus forming an enclosure for the spool  14  and other movable components of the retractable lifeline  10 . In the exemplary embodiment illustrated, the spring side portion  18  and the sprocket side portion  20  of the housing  16  are held together by at least one, but preferably a plurality of bolts  22 , However, it will be understood by those skilled in the art that any suitable means for removably securing the halves  18  and  20  together may be employed, including, but not limited to screws, ties, seals and the like. One end of the cable  12  terminates to a fastening mechanism  24  such as a hook, eye, or the like for attaching to or securely clipping to a safety harness worn by a worker or climber. The opposed end is fixed to the spool  14  upon which the cable  12  is wound about. 
         [0034]    The housing  16  is secured to an elevated surface or a person (not shown) by a swivel assembly  26  having a swivel bolt  28  with a swivel base  30 , the swivel bolt  28  being rotatably engaged with one or more bearing washers  32  and a swivel body  34 . In exemplary embodiments, the swivel assembly  26  securely connects to an elevated surface (not shown) and allows the retractable line  10  to freely rotate while maintaining engagement with the surface. The end of the swivel bolt  28  opposite the swivel base  30  has an enlarged portion  36  that is contained within and held by the housing  16 , as best shown in  FIG. 6 , thus securing the retractable line  10  to the swivel assembly  26 . When the lifeline  10  is secured to an elevated point by the swivel assembly  26 , it may twist and rotate about the swivel assembly  26  to reduce any wind of the cable  12  caused by the rotation. In exemplary embodiments, the lifeline  10  may also be provided with a plurality of washers or needle/roller type bearings in the swivel assembly  26  operable for reducing the frictional forces which may be exerted on the swivel assembly  26 . Thus, the wear or damage to the swivel assembly  26 , cable  12  or the housing  16  is reduced, thereby extending the useable life of the retractable line  10 . 
         [0035]    Contained within the housing  16 , the spool  14  is supported by an axle  38  horizontally supported by and spanning the distance between the spring side portion  18  and the sprocket side portion  20  of the housing  16 . The axle  38  has a slot  40  running lengthwise from the spring side portion  18  to approximately the middle of the axle  38  for receiving a portion of a power spring  50 . The end of the axle  38  nearest the sprocket side portion  20  of the housing  16  has rotation-prevention means, such as a hole  42  through which a pin  44  is inserted. The pin  44  nests securely within a pin slot  46  on the sprocket side portion  20  of the housing  16  such that the pin  44  and axle  38  are prevented from rotating during normal operation when subjected to centrifugal forces as the cable  12  is withdrawn from and retracted into the housing  16 . 
         [0036]    A power spring assembly  48  operable for biasing the spool  14  to rotate in the retractable direction, an exploded view of which is illustrated in  FIG. 4 , is mounted adjacent to the spring side portion  18  and contains the power spring  50 . The inner end of the power spring  50  terminates in an axle hook  52  that fits securely within the slot  40  in the axle  38 . The exterior end of the power spring  50  terminates in a spool hook  54  that fits into a hook relief  56  and a spool slot  58 . The power spring  50  has a band  60  that holds the power spring  50  together. The band  60  passes around the power spring  50  and through a band hole  62  in the end of the power spring  50  such that the band  60  forms a continuous, unbroken loop surrounding the power spring  50 . A spring cover  64  attaches to the spool assembly  14  such that the spring cover  64  encases the power spring  50  within the spool  14  by conventional means  66  such as, for example, screws. The spring cover  64  has a cover hole  68  in its center such that the axle  38  passes through the spring cover  64  and into the spring side portion  18  of the case  16 . Thus, the spring cover  64  and spool  14  are free to rotate around the axle  38 . The use of the band  60  eliminates a stress concentration on the edge of the conventional weld which is used for the power spring. Further, by using the band  60 , the power spring may be more compact in size. This is a specific advantage over conventional lifelines which typically use a rivet or screw to hold the band and/or the power spring together. 
         [0037]    Referring now to  FIG. 2-5 , it can be seen that the end of the cable  12  that attaches to the hook  24  forms a loop  70  by looping back on itself and being secured by at least one, but preferably two duplex ferrules  72 . Such loop attaches to the hook  24  and protrudes from a cushion  74  that comprises a cylindrical tube encasing the duplex ferrules  72 . Such cushion  74  can absorb shock in the event that the retraction of the cable  12  reaches a velocity that would cause impact damage to the housing  16 . The opposite end of the cable  12  is secured inside the housing  16  to the spool  14  by means of a cable stop  76 . A portion of the cable  12 , the reserve cable  78 , is fixed to a spool drum  80  about which the cable  12  winds and unwinds. The cable stop  76  secures the end of the cable  12  to the spool drum  80  creating the terminal end of the reserve cable  78 . On the end of the reserve cable  78  opposite to the cable stop  76 , a clamp  82  secures the reserve cable  78  to the spool drum  80 . Advantageously and distinct from conventional lifelines, the clamp&#39;s flat portion is oriented to allow easy access to the screw without having to move the cable  12 . During normal operation of the retractable line  10 , the cable  12  may be withdrawn up to the point at which the clamp  82  engages the cable  12 . The clamp  82  is preferably attached to the spool drum  80  by a clamp screw  84  accessed from the exterior of the spool drum  80 . However, it will be appreciated and understood by those skilled in the art that any means for securing the clamp  82  to the spool drum  80  may be used. The clamp screw  84  attaches to a clamp flat  86 . The clamp flat  86 , screw or hole threads, is sized to break off at a predetermined load. Thus, in the event of a fall, the clamp flat  86  breaks and allows the reserve cable  78  to be withdrawn from the spool  14 , thus providing additional time to slow the rate of extrusion of the cable  12  from the spool  14  and slowing the rate of descent. In addition, the power spring  50  may be sized to have just enough turning capacity to extend and retract only the cable  12  that does not include the reserve cable  78 . When the clamp  82  releases the reserve cable  78  and it is withdrawn, the spool  14  continues to rotate which will cause the pin to break and allow the spool  14  to release the reserve cable  78  even though the power spring  50  has reached the limit of its extension turns. 
         [0038]    Referring now specifically to  FIG. 3 , it can be seen that on the lower end of the housing  16  where the cable  12  exits, a cable guide  87  separates the cable  12  from the body of the housing  16  and prevents the cable  12  from rubbing against the housing  16  while it is withdrawn and retracted. The cable guide  87  has a cable guide tab  88  protruding around its perimeter for engagement with the housing  16 . The cable guide tab  88  is held in place, or nested, within the housing  16  by a cable guide mount  90 . This has the advantage of allowing for molding the cable guide  87  with only one pull direction instead of two pull directions, as required by conventional lifelines. In other exemplary embodiments, the lifeline  10  may be provided with cable guide mounts extending along a back wall of the housing between the mounts. This would extend the mounts all the way around the cable guide. 
         [0039]    Within the spool  14  and adjacent to the power spring  50  is a braking system having a centrifugal clutch mechanism. In exemplary, embodiments, the centrifugal clutch mechanism includes at least one, but preferably two pawls, pawl A  92  and pawl B  94 . In exemplary embodiments, pawls A  92  and B  94  are mounted on pawl axle A  96  and pawl axle B  98 , respectively. Pawls A  92  and B  94  are held on the pawl axle  96  and  98  by pawl washers  100  and snap rings  102 . Pawls A  92  and B  94  are preferably, rotatably mounted on pawl axle A  96  and pawl axle B  98  such that pawl A  92  and pawl B  94  can freely rotate. In exemplary embodiments, the rotation of pawl A  92  and pawl B  94  is arrested by pawl springs  104  that attach the tip of pawl A  92  to the end of pawl B  94  and the tip of pawl B  94  to the end of pawl A  92 . The pawl springs  104  exert enough force on the ends of pawl A  92  and pawl B  94  to keep pawl A  92  and pawl B  94  in a stationary position, disposed inwardly toward each other and the axle  38 . During normal operating conditions, pawl A  92  and pawl B  94  do not rotate about the axles and thus cable  12  is withdrawn and retracted without interruption. A pawl stop A  126  and a pawl stop B  128  are placed adjacent to the axle  38  to limit the extent of the rotation of pawl A  92  and pawl B  94 . Pawl stop A  126  limits rotation of pawl A  92  and pawl B  94  inward to prevent the pawl springs  104  from being compressed and to decrease the amount of rotation available for pawl acceleration. Likewise, pawl stop B  128  prevents pawl A  92  and pawl B  94  from overextending during production when a sprocket may not be present. The pawl stops further prevent damage to the pawl springs from spring surge by limiting the distance the pawl could accelerate. A pair of spring guards  130  are attached to the axle  38  in opposite relation between pawl A  92  and pawl B  94  such that the spring guards  130  provide protection to the pawl springs  104 . Specifically, the spring guards  130  are used to prevent the pawl springs from being replaced without removing the pawls from the pawl axles. Attempting to replace the pawl springs while the pawls are still assembled causes excessive trauma to the pawl springs. 
         [0040]    Inside the sprocket side portion  20  of the housing  16  is a friction ring  106  that nests against the sprocket side portion  20  of the housing  16 . Adjacent to the friction ring  106  is a sprocket  108 . On the opposite side of the sprocket  108  from the friction ring  106  is at least one of the washers  110  and the pressure plate  112 . The pressure plate  112  is held against the washers  110  and secured to the sprocket side portion  20  of the housing  16  by a plurality of pressure plate screws  114 . The pressure plate screws  114  securely attach the pressure plate  112  to the sprocket side portion  20  of the housing  16  and prevent the pressure plate  112  from moving. The pressure plate screws  114  are tightened to a predetermined load, thereby pressing the pressure plate  112  into the washers  110 , effectively exerting a compression force on the washers  110 , the sprocket  108 , and the friction ring  106 . It will be understood by those skilled in the art that the friction components of the present invention are what slows and stops descent of a worker or object in the event of a fall. The pressure of the sprocket  108  against the friction ring  106  creates the drag friction needed to arrest the rotating spool  14 . Spring loading the sprocket creates a more consistent friction between the sprocket and the friction ring. Using washer type springs which are approximately the diameter of the sprocket allows for a more compact mechanism. Such washer type springs are known as wave washers and Belleville washers. 
         [0041]    During normal operation of the retractable line  10 , pawl A  92  and pawl B  94  rotate freely within the friction ring  106 , sprocket  108 , washers  110 , and pressure plate  112 . This is shown in  FIG. 7  by pawl B  94  and its position in relation to the sprocket  108 . A sheave  116  attaches to the spool drum  80  by means of a plurality of sheave screws  118  and prevents the cable  12  from contacting the washers  110 , the sprocket  108 , and the friction ring  106 . In the event of a fall, the spool  14  will initially rotate at a high rate of speed as the cable  12  is rapidly withdrawn from the retractable line  10 . As a result of this high-speed withdrawal of the cable  12 , the spool  14 , including pawl A  92  and pawl B  94  will rapidly rotate around the axle  38 . This rapid rotation creates a centrifugal force upon the tip of pawl A  92  and pawl B  94  of such magnitude as to overcome the compression force of the pawl springs  104 . As the centrifugal force overcomes the compression force of the pawl springs  104 , pawl A  92  begins to rotate around pawl axle A  96  and pawl B  94  begins to rotate around pawl axle B  98 . As pawl A  92  and pawl B  94  continue to rotate on pawl axle A  96  and pawl axle B  98  respectively, the tips of pawl A  92  and pawl B  94  will come into contact with the sprocket  108 . As pawl A  92  and pawl B  94  contact the sprocket  108 , the tips of pawl A  92  and pawl B  94  will each slide into one of a plurality of root areas  120  of the sprocket  108 . This is best shown in the exemplary embodiment of  FIG. 7  by the position of pawl A  92 . Once pawl A  92  and pawl B  94  have engaged the sprocket  108  and are nested in the root areas  120 , the rotational force of the spool assembly  14  is transferred to the sprocket  108 . This causes the sprocket  108  to rotate against the washers  110  and the friction ring  106 . The frictional resistance caused by the compression force from the pressure plate  112  compressing the washers  110 , friction ring  106 , and sprocket  108  causes the sprocket  108  to slow its rotation. This, in turn, slows the rotation of pawl A  92  and pawl B  94  and thus slows the rotation of the spool  14 . As the rotation of the spool  14  is slowed and slopped, the withdrawal of the cable  12  from the retractable line  10  is slowed and stopped and, thus, the fall is arrested. 
         [0042]    As seen best in  FIG. 9 , another exemplary embodiment is available that makes use of at least one washer-type spring, such as a wave washer and/or a Belleville washer  122 . In this embodiment, the sprocket  108  has a shoulder  124  around its perimeter. The pressure plate  112  rests directly above the shoulder  124  and a plurality of Belleville washers  122  separates the pressure plate  112  from the shoulder  124 . The pressure plate screws  114  are tightened to cause the pressure plate  112  to compress the Belleville washers  122  against the sprocket  108 . This compression force acts to slow and stop the rotation of the sprocket  108  in the event of a fall. A third embodiment consists of a Belleville washer with or without another washer that bears directly on the sprocket or on a shoulder of the sprocket. The shoulder of the sprocket would provide a radius and act to spread out the contact area of the Belleville washer on the sprocket. 
         [0043]    Referring back to  FIG. 7 , the sprocket  108  has a tooth  132  with a terminal end disposed at a predetermined tooth ramp angle  134  such that the tooth  132  protrudes slightly further toward pawl A  92  and pawl B  94 . During normal operation of the retractable line  10  pawl A  92  and pawl B  94  do not engage the sprocket  108  or contact the tooth  132 . As the centrifugal force begins to rotate pawl A  92  and pawl B  94  on pawl axle A  96  and pawl axle B  98 , the tips of pawl A  92  and pawl B  94  will contact the tooth  132  causing an audible click. The tooth  132  is inclined at the tooth ramp angle  134  such that pawl A  92  and pawl B  94  will bounce off the tooth  132 , missing the root area  120  and failing to engage the sprocket  108 . As the velocity and centrifugal force increases, pawl A  92  and pawl B  94  will rotate further and will overcome the tooth ramp angle  134  and enter the root area  120  thus engaging the sprocket  108 . Referring now to  FIG. 8 , another exemplary embodiment of the sprocket  108  is shown. As shown, the tooth  132  is provided with a distinct configuration from that illustrated in  FIG. 7 . Specifically, the tooth  132  is provided with a ramped surfaced having a generally planar tip. 
         [0044]    The housing  16  is strengthened by inclusion of case indents  136  as seen on  FIG. 10 . In exemplary embodiments, the case indents  136  are generally comprised of the indent web wall  138  and the indent vertical wall  140 . The case indents  136  follow the contour of the spool  14 . These case indents  136  strengthen the housing  16  and add little weight. Further, the case indents  136  do not decrease the clearance for the internal components because they follow the circular outline of the spool  14 . 
         [0045]    The embodiments described above provide advantages over conventional retractable lifelines and associated methods of manufacture. It will be apparent to those skilled in the art that various modifications and variations can be made to the present invention without departing from the spirit and scope of the invention. Thus, it is intended that the present invention cover the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.