Patent Publication Number: US-10760336-B2

Title: Fall arrester

Description:
FIELD OF THE INVENTION 
     The present invention relates broadly to a fall arrester. 
     BACKGROUND TO THE INVENTION 
       FIG. 1  illustrates a common rope access system used for descent of a user  1  where a descender device  2  engages a working rope  3  for controlled descent, and a fall arrester  4  engages a backup rope  5 . If the descender device  2  or other associated equipment fails, the fall arrester  4  automatically brakes on the backup rope  5  to arrest fall of the user  1 . There are various fall arrester designs which can be generally categorised as either automatic hands-free followers or back-up manual devices. 
     In a typical automatic follower there is provided a housing having a hinged gate for enclosing the backup rope. The follower also includes a large cam and lever with a head of the lever coupled to a user&#39;s harness via a lanyard and carabiner-style snap hook. If the user falls the lever pivots the large cam which brakes the backup rope within the housing. 
     In a typical manual device there is provided a primary cam for braking where the user&#39;s carabiner and lanyard is connected to a body of the device. The body includes a pivoting cover plate which can be opened for locating the fall arrester on the backup rope. The manual device, on rapid descent of a user, rocks the housing relative to the primary cam for braking of the rope. The manual device also includes a secondary cam and lever which connects to the user&#39;s carabiner so that rocking of the housing is promoted by the secondary cam which frictionally engages the backup rope. This style of manual device presents a dropped objects hazard in that it must be detached from the user&#39;s carabiner when attaching to the backup rope. 
     It is to be understood that any acknowledgement of prior art in this specification is not to be taken as an admission that this prior art forms part of the common general knowledge. 
     SUMMARY OF THE INVENTION 
     According to a first aspect of the present invention there is provided a fall arrester comprising:
         a body adapted to couple to a user via a coupling;   a lever including a primary cam, the lever pivotally coupled to the body and arranged to cooperate with the coupling whereby in operation descent of the user urges the coupling into contact with the lever which pivots to effect braking of rope passing through the fall arrester between the primary cam and the body.       

     Preferably the fall arrester also comprises an inertial cam pivotally coupled to the lever proximate the primary cam and configured on rapid descent of the user to pivot into contact with the rope to initiate pivotal movement of the lever for braking of the rope with the primary cam. 
     According to a second aspect of the invention there is provided a fall arrester comprising:
         a body adapted to receive a rope;   a lever including a primary cam arranged to brake the rope on descent of the fall arrester, the lever pivotally coupled to the body;   a tow cam movably coupled to the body and configured to contact the lever to pivot it and release the primary cam from the rope to permit manual towing of the fall arrester along the rope during its descent.       

     Preferably the body includes a closed opening adapted to retain the coupling. More preferably the lever is positioned relative to the closed opening whereby ascent of the user provides contact of the coupling with the body to effect raising of the fall arrestor independent of the lever and the primary cam. 
     Preferably the fall arrester also comprises a secondary cam connected to the lever whereby gripping the rope and the coupling toward one another urges the rope into contact with the secondary cam pivoting the lever to promote braking of the rope between the primary cam and the body. More preferably the secondary cam is pivotally connected to the lever and biased to maintain contact with the rope to hold the fall arrester at a required position along the rope. Even more preferably the fall arrester further comprises a secondary cam lock connected to the lever and arranged to lock the secondary cam in a retracted position to permit sliding movement of the fall arrester in both directions along the rope. 
     Preferably the fall arrester additionally comprises a tow cam pivotally coupled to the body to provide contact with the lever to pivot it and release the associated primary cam from the rope to permit manual towing of the fall arrester along the rope on its descent. More preferably the tow cam is configured relative to the lever to disengage from the lever to permit braking of the rope via the primary cam beyond a predetermined pivot angle of the tow cam. Even more preferably the tow cam connects to a tow line which is manually pulled to pivot the tow cam to allow towing of the fall arrester. Still more preferably the tow line includes a mechanical fuse which breaks at a predetermined pull load wherein the tow cam is deactivated. 
     Preferably the fall arrester still also comprises an accelerator element pivotally coupled to the body and adapted to engage the coupling to accelerate contact of the coupling with the lever for accelerated braking of the rope with the primary cam. More preferably the accelerator element is operatively coupled to a biasing member which urges the coupling to maintain contact with the lever. 
     Preferably the body includes a base body and a movable cover plate which in an open position provides for attachment of the fall arrester to the rope. More preferably the body is configured with the cover plate in a closed position to substantially house at least the primary cam and the lever. Even more preferably the body includes an inverted cam movably mounted to the base body to only permit closure of the cover plate into the closed position with the fall arrester correctly oriented relative to the rope to ensure braking on descent. 
     Preferably the fall arrester is integrally connected to the coupling. More preferably the coupling is in the form of a swivel connector. 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
       In order to achieve a better understanding of the nature of the present invention preferred embodiments of a fall arrester will now be described, by way of example only, with reference to the accompanying drawings in which: 
         FIG. 1  is a schematic illustration of a common rope access system including a fall arrester; 
         FIG. 2  is a perspective view of a fall arrester of an embodiment of the invention together with a coupling; 
         FIGS. 3A and 3B  are perspective views of the fall arrester of  FIG. 2  together with different length coupling arrangements; 
         FIGS. 4A and 4B  are side elevational views of the fall arrester of  FIG. 2  in closed and open configurations respectively; 
         FIG. 5  is a side elevational view of the fall arrester of the embodiment of  FIGS. 4A and 4B  with the cover plate removed for clarity; 
         FIGS. 6A and 6B  are side elevational views of the fall arrester of  FIG. 5  shown in automatic and manual modes respectively; 
         FIGS. 7A and 7B  are side elevational views of the fall arrester of  FIG. 5  in the automatic mode; 
         FIGS. 8A and 8B  are side elevational views of the fall arrester of  FIG. 5  in the manual mode; 
         FIG. 9  is a schematic illustration of the fall arrester of  FIG. 5  shown in the case of a “panic grip”; 
         FIG. 10  is a perspective view of the fall arrester of  FIG. 5  in an inverted position. 
         FIGS. 11A and 11B  are perspective views of a fall arrester of another embodiment of the invention shown with the cover plate removed for clarity; 
         FIGS. 12A and 12B  are side elevational views of the fall arrester of  FIGS. 11A and 11B ; 
         FIG. 13  is a cross-sectioned view of the fall arrester of  FIGS. 11A and 11B  shown in the automatic mode braking the rope. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     As best shown in  FIGS. 2 and 3A / 3 B there is a fall arrester  10  according to a preferred embodiment of the present invention which is coupled to a user&#39;s harness (not shown) via a coupling arrangement  6 . In this embodiment the coupling arrangement  6  includes a coupling in the form of a swivel connector  7  connected integral with the fall arrester  10 . The swivel connector  7  is connected to either a short or long lanyard  8  as shown in  FIGS. 3A and 3B , respectively. The lanyard  8  is at an opposite end connected to a carabiner  9  which detachably connects to a connection point defined by a D-ring (not shown) attached to the harness. 
     As best shown in  FIGS. 4A /B and  5  the fall arrester  10  is designed to be attached to a backup rope or safety line  12 . The fall arrester  10  comprises a body  14 , and a lever  16  pivotally coupled to the body  14 . The lever  16  includes a primary cam  18  which in this embodiment is formed integral with the lever  16  which is arranged to co-operate with a coupling, an example of such a coupling being the coupling arrangement  6 . In operation, descent of the user urges the coupling into contact with the lever  16  which pivots to effect braking of the safety line  12  between the body  14  and the primary cam  18 . 
     The body  14  includes a base body  20  and a moveable cover plate  22  which in this example pivots about the base body  20 . The base  14  includes a pivot axle  24  about which the cover plate  22  pivots. The pivot axle  24  also provides a pivotal mount to which the lever  16  is pivotally coupled. The base body  20  together with the cover plate  22  define a closed opening  26  designed to retain the coupling. The base body  20  and the cover plate  22  are slotted so that the opening  26  is maintained for connection to the coupling with the cover plate  22  both closed and open as illustrated in  FIGS. 4A and 4B  respectively. 
     The base body  20  includes a retaining button  28  which retains the cover plate  22  in the closed position of  FIG. 4A . The retaining button  28  is depressed to release the cover plate  22  and allow it to pivot about the pivot axle  24  into its open position as shown in  FIG. 4B . In operation, ascent of the user releases the coupling from the lever  16  and the coupling contacts the body  14  about the opening  26  to effect raising of the fall arrester  10  independent of the lever  16  and the primary cam  18 . As best illustrated in  FIG. 5 , the primary cam  18  under the influence of gravity pivots away from the safety line  12  for relatively free movement of the fall arrester  10  along the safety line  12 . In this embodiment the lever  16  and primary cam  18  are otherwise not actively biased. 
     The fall arrester  10  further comprises an accelerator element  30  pivotally coupled to the base body  20 . The accelerator element  30  is biased via a biasing member in the form of a torsion spring (not shown) in a clockwise direction as viewed in  FIG. 5  to maintain contact with the coupling. This means that on rapid descent of a user the coupling is forced by the accelerator element  30  into contact with the lever  16  to initiate braking of the safety line  12  with the primary cam  18 . The accelerator element  30  thus avoids a situation where the fall arrester  10  accelerates at the same rate as the user without the coupling contacting the lever  16  to effect braking via the primary cam  18 . 
     The fall arrester  10  also comprises a secondary cam  32  connected to the lever  16 . The secondary cam  32  is designed so that gripping the safety line  12  and the coupling toward one another forces the safety line  12  into contact with the secondary cam  32 . This contact with the secondary cam  32  pivots the lever  16  in a clockwise direction as shown in  FIG. 6B  to promote braking of the safety line  12  between the primary cam  18  and the body  16 . The secondary cam  32  in this embodiment is pivotally connected to the lever  16  to permit operation of the fall arrester  10  in either an automatic or manual mode as shown in  FIGS. 6A and 6B  respectively. 
     The fall arrester  10  further comprises a secondary cam lock  34  mounted on the lever  16  and designed to retain the secondary cam  32  in a fixed and retracted position in the automatic mode. The secondary cam lock  34  is depressed to release the secondary cam  32  which is biased to pivot outwardly of the lever  16  into frictional engagement with the safety line  12  in the manual mode. 
     In the automatic mode as shown in  FIG. 7A  the fall arrester  10  is free to slide or float in both upward and downward directions along the safety line  12 . In moving upwardly along the safety line  12  the coupling lifts the body  14  of the arrester  10  without influencing pivoting of the lever  16  which under the influence of gravity pivots in an anti-clockwise direction moving the primary cam  18  away from the safety line  12 . The fall arrester  10  similarly travels downwardly along the safety line  12  without gripping the safety line  12 . In travelling in both directions the secondary cam  32  is retracted clear of the safety line  12 . In rapid descent the fall arrester  10  is activated wherein the accelerator element  30  pushes the coupling into contact with the lever  16  to rotate the primary cam  18  in a clockwise direction to effect accelerated braking of the safety line  12  with the primary cam  18 . 
     In the manual mode as illustrated in  FIGS. 8A and 8B  the secondary cam  32  is biased toward the safety line  12  by releasing or depressing the secondary cam lock  34 . The secondary cam  32  thus maintains frictional engagement with the safety line  12  pivoting the lever  16  in a clockwise direction to press cam  18  against the safety line  12 . This means that the fall arrester  10  is held stationary or parked at a required position along the safety line  12 . The secondary cam  32  thus forces the primary cam  18  to lightly brake the safety line  12  to effectively park the fall arrester  10  at a required height. If the user rapidly descends or falls the coupling contacts the lever  16  pivoting the primary cam  18  to brake the safety line  12  against the body  14 . 
     The fall arrester  10  as best illustrated in  FIGS. 8A and 8B  also comprises a tow cam  36  pivotally coupled to the base body  20 . The tow cam  36  is designed in the manual mode to tow the fall arrester  10  downwardly along the safety line  12 . The tow cam  36  is configured to contact an underside surface  38  of the lever  16  to pivot the lever  16  in an anti-clockwise direction to release the associated primary cam  18  from the safety line  12 . A tow line  40  is connected to the tow cam  36  so that when the tow line  40  is pulled it pivots the tow cam  36  in the anti-clockwise direction. The tow cam  36  is actuated independent of the primary cam  18  via the tow line  40 . The lever  16  at its underside surface  38  is shaped wherein the tow cam  36  beyond a predetermined pivot angle disengages from the lever  16 . Up until the predetermined pivot angle, the tow cam  36  bears against the underlying surface  38  of the lever  16  to pivot the lever  16  and release the primary cam  18  from the safety line  12 . The secondary cam  32  in the manual mode maintains frictional contact with the safety line  12  for smooth lowering of the fall arrester  10 . The tow line  40  includes a mechanical fuse such as the breakaway cord  42  shown in  FIG. 9 . The breakaway cord  42  detaches from the remainder of the tow line  40  at a predetermined pull load wherein the tow cam  36  is deactivated. The tow cam  36  is biased in a clockwise direction via torsion spring  43 . 
     The body  14  of the fall arrester  10  of this embodiment houses the lever  16  and primary cam  18  together with the majority of the other moving components. The lever  16  is open-ended so that it is only effective in pivoting of the associated cam  18  on contact with the coupling in descent only. As illustrated in  FIG. 9 , this also means that in a “panic grip” the coupling or in this example the carabiner  43  does not contact the lever  16  and influence the primary cam  18 . Rather, the secondary cam  32  in a “panic grip” contacts the safety line  12  and pivots the lever  16  and the associated cam  18  into braking contact with the safety line  12 . The carabiner  43  moves freely within the slotted opening  26  with the accelerator element  30  being pivoted away against its biasing force. 
     The fall arrester  10  as shown in  FIG. 10  is configured so that it can be attached to the safety line  12  in a single orientation only wherein braking of the safety line  12  is effected on descent of the fall arrester  10 . For this purpose the base body  20  is provided with an invert cam  44  which pivotally retracts with the fall arrester  10  oriented in the correct disposition. With the invert cam  44  retracted, the cover plate  22  is free to pivot across the base body  20  for retention with the button retainer  28 . If the fall arrester  10  is incorrectly oriented relative to the safety line  12 , the invert cam  44  extends from the base body  20  as shown in  FIG. 10 . This means the cover plate  22  is obstructed by the invert cam  44  not permitting full closure of the cover plate  22 . This consequently alerts the user to incorrect orientation of the fall arrester  10 . 
     In order to further understand the invention, operation of the preferred fall arrester  10  involves the following steps: 
     1. In a safe environment, the fall arrester  10  which is integrally connected to a coupling is connected to a user&#39;s harness via a lanyard and carabiner; 
     2. The fall arrester  10  is opened by depressing the retainer button  28  and pivoting the cover plate  22  anti-clockwise to present an elongate passage for attaching or capturing the safety line  12 ; 
     3. The cover plate  22  is pivoted in a clockwise direction for closure about the safety line  12 ; 
     4. The user descends a working rope using a conventional descender device and relies upon the fall arrester  10 , typically in the automatic mode, to function as a backup safety device; 
     5. The user having descended to a required working height can elect to park the fall arrester  10  in a manual mode at a required height along the safety line  12 ; 
     6. The user can tow the fall arrester  10  in the manual mode sliding it downwardly along the safety line  12  using the tow line  40  and associated tow cam  36 . 
     In the event of a fall or rapid descent, the fall arrester  10  in either its automatic or manual mode brakes or locks against the safety line  12  to arrest descent of the user. 
     If the tow line  40  is being used with the breakaway cord  42 , the breakaway cord  42  will detach from the remainder of the tow line  40  and the tow cam  36  will be deactivated. 
       FIGS. 11 to 13  show another embodiment of a fall arrester according to the present invention. The fall arrester  100  of this embodiment is essentially the same as the preceding embodiment except for the inclusion of an inertial cam  130 . For ease of reference and in order to avoid repetition the fall arrester  100  is for corresponding components to the preceding embodiment shown or designated with an additional “0”. For example, the housing of this fall arrester  100  is designated as  140 . 
     As best shown in  FIG. 11A  the inertial cam  130  is pivotally connected to the lever  160  at the primary cam  180 . The inertial cam  130  pivots or swings about pivot pin  150  fixed to the lever  160  at the primary cam  180 . The inertial cam  130  is configured on rapid descent of a user to pivot into contact with the rope  120  as shown in  FIG. 11B . The inertial cam  130  contacts the rope  120  and thus initiates pivotal movement of the lever  160  and the associated primary cam  180  for braking of the rope  120  with the primary cam  180 . The inertial cam  130  can thus swing from a retracted position of  FIG. 11A  for normal operation of the fall arrester  100  to an extended position of  FIG. 11B  for activation of the primary cam  180 . 
     As shown in  FIGS. 12A and 12B  the fall arrester  100  can operate in an automatic mode with the secondary cam  320  in a fixed and retracted position. In the automatic mode the fall arrester  100  is free to slide or float in both upward and downward directions along the rope or safety line  120 . In the event of rapid descent which may be associated with a panic grip, the inertial cam  130  as shown in  FIG. 12B  is swung outward of the primary cam  180  due to the inertia difference in the system. The inertial cam  130  includes teeth such as  170  designed to contact and pick up the rope  120  and thus initiate locking of the primary cam  180 . In rapid descent the falling mass further activates the primary cam  180  for braking of the rope  120  to arrest the fall. 
       FIG. 13  depicts the fall arrester  100  with the rope  120  braked following rapid descent. Inertial cam  130  has retracted into a rebate  190  in the lever  160  at the primary cam  180 . The inertial cam  130  in this retracted position does not contact or damage the rope  120 . The fall arrester  100  is otherwise constructed to operate in a similar manner to the preceding embodiment. 
     Now that several preferred embodiments of the present invention have been described it will be apparent to those skilled in the art that the fall arrester has at least the following advantages: 
     1. The fall arrester is retained on the coupling or carabiner and lanyard whilst being attached or detached from the safety line thus eliminating a drop hazard; 
     2. The fall arrester can be operated in either an automatic or manual mode and these modes can be switched whilst in operation with relative ease; 
     3. The fall arrester eliminates hazards associated with a “panic grip” by one or a combination of the following design features:
         i. The body houses the lever and associated primary cam so that the lever cannot be grasped;   ii. The carabiner or other coupling is not retained by the lever but rather contacts or engages the lever on descent only;   iii. The secondary cam on contact with the safety line urges the primary cam into braking contact with the safety line;   iv. The primary cam may include an inertial cam which ensures braking of the rope;       

     4. The fall arrester can be safely towed via the tow cam which is activated independent of the primary braking cam; 
     5. The tow cam is designed to deactivate if over pulled by panic. 
     Those skilled in the art will appreciate that the invention described herein is susceptible to variation and modifications other than those specifically described. For example, the shape and configuration of the fall arrester and its associated components may vary from that described provided it functions in accordance with the essential characteristics of the invention. The fall arrester need not necessarily include the secondary cam in which case it would function in the automatic mode only. All such variations and modifications are to be considered within the scope of the present invention the nature of which is to be determined from the foregoing description.