Patent Document

CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims priority from PCT/GB/2011/052253 filed on Nov. 18, 2011, GB 1019462.9 filed on Nov. 18, 2010, and GB 1112332.0 filed on Jul. 18, 2011, all of which are hereby incorporated by reference in their entireties. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a rescue descender system primarily, but not exclusively for use in fall arrest or fall safety systems for personnel safety when working at height. 
     2. State of the Art 
     Fall arrest or fall safety systems are known in which personnel working at height are secured to a safety line in order to arrest a fall, should this occur. Such safety lines can comprise a self retracting lifeline which includes a safety block secured to an anchor point and a safety line which pays out as the user moves away from the safety block. A brake device engages to prevent paying out of the safety line in the event of a fall. Typically the system includes an energy absorption device arranged to absorb the energy of the fall when the line payout stops in order to arrest the fall. 
     Typically, in the circumstances of a fall, the user can be left suspended in mid air. In order to be rescued, the user can be hooked from above by a rescuer (if in reach and accessible), or a rescuer can descend to the individual to attach them to a rescue line. Alternatively, devices have been proposed to enable a suspended user to self instigate lowering to ground or rescue level. Such arrangements are disclosed in, for example, GB2414005 and WO2009/027619. Such systems can be referred to as self rescue devices. 
     GB2414005 discloses a rescue descender system comprising a casing, which incorporates a bracket for attachment to a person&#39;s body harness whereby the bracket can be releasably attached to a load element attached to a safety line and the safety line may then be attached to a secure anchorage. Various release mechanisms are disclosed including release that is initiated remotely such as by the transmission and receipt of radio signals. The receipt of radio signals may be used to initiate the activation of an actuator that can then carry out the release operation. An example given of a typical actuator is a pyrotechnic actuator (explosive squib) that is initiated electrically. When the load element is released from the bracket, elongate that is also attached to the load element is deployed at a speed controlled by a speed control means thereby controlling the descent of the person being rescued. 
     When a person is arrested after a fall, loads of up to 6 kN can be applied between the harness and safety line 
     WO2009/027 length of descent line 619 discloses methods of attaching the rescue apparatus to a harness in normal use whereby the weight of the rescue apparatus is supported at least in part by alternative means other than the rigid load elements described in GB2414005. 
     In both documents identified, the prior art systems described use a descent line that is payed out from the descent reel is connected to the safety line by a load element and a release means actuated to permit release of the load element to allow paying out of the descent line from the descent line reel or store. In both prior art arrangements the full load of the fall and the suspended user is passed via the release means. This results in a high force necessary to effect release of the release means. Hence in WO2009/027619 the invention utilises detonation of an explosive squib as an exemplary release means for releasing the release pin  15 . 
     SUMMARY OF THE INVENTION 
     An improved arrangement has now been devised. 
     According to a first aspect, the present invention provides a descender device for enabling a suspended body to be lowered, the descender device comprising:
         a descent line,   a release element to be actuated by a person, the release element arranged in a restraint configuration to inhibit the descent line from being deployed and in a release configuration to permit the descent line to be deployed; wherein,   a restraint arrangement is arranged prior to deployment of the descent line, to clamp or pinch a length of flexible line thereby to inhibit deployment of the descent line, the restraint arrangement being reconfigurable upon release of the release element to permit the descent line to be deployed.       

     The descent line may in use connected (either directly or by means of an intermediate line or lines or connectors) to a lifeline device such as a self retracting lifeline of a safety block. Connection loops, rings and/or karabiners may be provided for this purpose. 
     It is preferred that the release element is connected to a pull tether, which pull tether extends over a shoulder portion of a harness. 
     In one embodiment, it is preferred that the release element secures through a loop or ring, which loop or ring is attached to a flexible line. 
     In one embodiment, the release element may secure through a loop or ring formed in, or connected to, the descent line or a length of separate line, such as a binding line (which separate/binding line is typically connected to the descent line). 
     In one embodiment the release element may comprise a pin extending through the loop or ring, the loop or ring preferably being pulled off over the end of the pin when moving to the release configuration. 
     In one embodiment, the release element is preferably connected to a pull tether, which pull tether has a finger pull portion to be gripped by a user, and in addition to the finger pull portion, a second pull formation. 
     It may be preferred that the second pull formation is in use positioned adjacent the shoulder, torso or back of a user. This provides for ease of remote access to pull the tether by means of the second pull formation. 
     The second pull formation may comprise a loop or ring, preferably a rigid or semi rigid form, secured with respect to the pull tether and arranged to stand proud of the user when the device is mounted (typically by harness) to the user. 
     In a preferred embodiment the restraint arrangement comprises a clamp arrangement which is arranged to clamp or pinch a binding portion of the descent line and/or a length of separate binding line (which binding line is typically connected to the descent line). 
     Preferably, the binding portion, or binding line is clamped or pinched at one or more points intermediate the opposed ends of the line and spaced from the release element. 
     It may be preferred that movement of the release element to the release configuration permits (or causes) the restraint arrangement to reconfigure from the clamping position, to permit the line to pass. 
     In a preferred embodiment, the restraint arrangement comprises a plurality of spaced bars (pinch bars), the flexible line (for example the descent line and/or a binding line) preferably passing serpentine-wise through the bars. 
     It is preferred that the spacing of the bars on the rack can reduce to clamp or pinch the flexible line between the bars or expand to permit the line to pass via the bars in the rack. 
     Beneficially, moving of the release element to the release configuration permits or causes the spacing between the bars on the rack to increase from the reduced spacing configuration. 
     It is preferred that the flexible line (the descent line and/or a separate binding line) is secured relative to the release element in the restraint configuration to inhibit the descent line from being deployed and released from the release element in a release configuration, in order to permit the descent line to be deployed. 
     In one embodiment the binding line and the descent line are configured to both extend through the clamping arrangement before deployment of the release line. 
     In such an embodiment it is a preferred consequence that the descent line and the binding line are arranged to be drawn through the clamping arrangement in unison (preferably side by side) when the descent line is deployed. 
     The binding line and the descent line may beneficially be connected to one another (typically at a connector ring) at a position downstream deployment-wise of the clamping arrangement. 
     In certain embodiments, the release means may comprise a pin. 
     It is preferred that, when actuated to permit the descent line to be deployed the release element is forced to rupture or break a capture element (such as for example a breakable clip) securing the release element in the restraint configuration. 
     It is preferred that the descent line is stored on-board the descender device. 
     The descent line is preferably wound on a reel pending deployment. 
     The device preferably includes a brake arrangement to limit the deployment rate of the descender line. 
     According to a second aspect, the invention provides a descender device for enabling a suspended body to be lowered, the descender device comprising:
         a descent line,   a release element to be actuated by a person, the release element arranged in a restraint configuration to inhibit the descent line from being deployed and in a release configuration to permit the descent line to be deployed; wherein,   the release element is connected to a pull tether, which pull tether extends in a harness over a shoulder portion of the harness.       

     According to a further aspect, the invention provides descender device for enabling a suspended body to be lowered, the descender device comprising:
         a descent line,   a release element to be actuated by a person, the release element arranged in a restraint configuration to inhibit the descent line from being deployed and in a release configuration to permit the descent line to be deployed;   wherein, the release element secures through a loop or ring, which loop or ring is attached to a flexible line.       

     It is preferred that the release element comprises a pin extending through the loop or ring. 
     According to a further aspect, the invention provides a descender device for enabling a suspended body to be lowered, the descender device comprising:
         a descent line,   a release element to be actuated by a person, the release element arranged in a restraint configuration to inhibit the descent line from being deployed and in a release configuration to permit the descent line to be deployed; wherein, the release element is connected to a pull tether, which pull tether has a finger pull portion to be gripped by a user, and also spaced from the finger pull portion and a second pull formation.       

     The features described as preferred or optional in respect of the first aspect may also be considered preferred or optional features of the further aspects of the invention. 
     According to a further aspect, the invention provides a descender system for enabling a suspended body to be lowered, the descender system comprising:
         a descent line,   a descender device provided with a release element arranged in a restraint configuration to inhibit the descent line from being deployed and in a release configuration to permit the descent line to be deployed, wherein:
           i) the descender device includes a load member movable between a first position in which the release element is restrained to be held in the restraint configuration and a second position in which the release element can be moved to the release configuration; and/or,   ii) the descender device includes a clamp arrangement arranged prior to deployment of the descent line, to clamp or pinch the descent line, or a length of line connected to the descent line, at one or more points intermediate the opposed ends of the line and spaced from the release means, the clamp arrangement being reconfigurable to permit the line to pass; and/or;   iii) the load of the suspended body imparted to the descender device is not transmitted primarily via the release element the load on the release element is substantially independent of the load imparted by the suspended body.   
               

     In accordance with the invention, the descent line can extend completely through the descender device as a unitary line or can be comprised of a plurality of connected lines tethers or webs. The descent line is in use connected (either directly or by means of an intermediate line or lines) to a lifeline device such as a self retracting lifeline of a safety block. Connection loops and/or karabiners may be provided for this purpose. 
     It is preferred that the load member is normally biased to the first position. This may be achieved by a spring element. 
     It is preferred that the load member is moved to the second position when a load is applied to the load member as a result of the person becoming suspended in a fall arrest event. This means that the load member moves effectively automatically to the second position when the person becomes suspended. 
     The load member preferably has an abutment portion which moves with the load member (and may in fact comprise a portion of the load member), the abutment portion abutting, engaging or otherwise blocking the release element in the first position (thereby preventing movement of the release element from the restraint configuration), and being removed from abutment or engagement with the release element in the second position (thereby permitting movement of the release element from the restraint configuration). 
     In a preferred embodiment, the load element is movable pivotably (or rotatably) between the first and second position. 
     It is preferred that the load element is arranged for attachment to a user wearable harness. 
     According to a further aspect, the present invention provides a fall arrest system incorporating a descender system as defined herein. 
     The invention will now be further described, by way of example only, and with reference to the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS   
         FIGS. 1A and 1B  are front and side views, respectively, of a first embodiment of a rescue descender device  1  in accordance with the invention in an initial or first configuration. 
         FIG. 2  is a schematic perspective exploded view of the rescue descender device  1  of  FIGS. 1A and 1B . 
         FIGS. 3A and 3B  are front and side views, respectively, of the rescue descender device  1  of  FIGS. 1A and 1B  in an alternative configuration. 
         FIGS. 4A and 4B  are front and side views, respectively, of the rescue descender device  1  of  FIGS. 1A and 1B  in a further configuration. 
         FIGS. 5A and 5B  are front and side views, respectively, of the rescue descender device  1  of  FIGS. 1A and 1B  in a final configuration. 
         FIGS. 6A ,  6 B,  6 C and  6 D are views showing the rescue descender device  1  of  FIGS. 1A and 1B  mounted to a harness worn by a user. 
         FIGS. 7A ,  7 B and  7 C are opposed side views and a front view, respectively, of an alternative embodiment in accordance with the invention, in a first (line pinching or clamping) configuration. 
         FIGS. 8A   8 B and  8 C are opposed side views and a front view corresponding to the views of  FIGS. 7A ,  7 B and  7 C but in an alternative (line pinching or clamping) configuration. 
         FIGS. 9A and 9B  are opposed side views of the arrangement of  FIGS. 7A to 8C  in a line released configuration. 
         FIG. 10  is a perspective view of the parts making up an alternative embodiment of a descender device according to the invention. 
         FIGS. 11A and 11B  are side and front views, respectively, of the embodiment of  FIG. 10 . 
         FIG. 12  is a front view of the embodiment of  FIG. 10  in an alternative configuration. 
         FIGS. 13A and 13B  are side and front views, respectively, of the embodiment of  FIG. 10  in an alternative configuration. 
         FIGS. 14A ,  14 B and  14 C are perspective views of a further embodiment of the invention in various sequential stages of operation. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring to the drawing there is shown a rescue descender device  1  in accordance with the invention. As shown in  FIGS. 6A to 6D , the rescue descender device  1  is arranged to be worn on the back of a user mounted to a body harness  30  and be conneted to fall arrest lifeline  36 , such as a self retracting lifeline as are known in the art. 
     The rescue descender device  1  comprises, a first length of binding webbing  2  comprising an upper loop  3 , a lower loop  4  and an intermediate webbing length  5  which is stitched together to form a double thickness between the upper and lower loops  3 , 4 . The upper loop  3  of the first length of webbing is arranged to be connected to a fall arrest lifeline such as the self retracting lifeline  36  as are known in the art. 
     The first length of binding webbing  2  is wrapped, serpentine fashion, around a restraint device  6  which comprises a U shaped frame  7  having spaced limbs  8 , at their upper ends joined by a curved crosspiece, and at their lower ends connected to a fixing bracket  9  connected to a descent line store device  10 . 
     A series of movable pinch bars  11  are mounted on the spaced limbs  8  and the first length of binding webbing  2  is wrapped around the movable pinch bars  11  as shown in the FIGS. in serpentine fashion. The movable bars  11  can slide up and own the spaced limbs  8 , upward movement being limited by a load arm mounting component  12  that is fixed relative to the U shaped frame  7 . The movable pinch bars  11  are provided with respective bores to accommodate the limbs  8 . The load arm mounting component  12  carries a pivotally mounted pivoting load arm  13  which has a cross bar  14  and a pair of spaced arms mounting arms  15   a    15   b . The pivoting load arm  13  is connected by a webbing loop harness connector  16  to the safety harness (not shown) worn by a user. The webbing loop harness connector  16  is looped around the cross bar  14  of load arm  13 . 
     The pivoting load arm  13  is provided with an abutment piece  17  such that when the pivoting load arm  13  is biased to its normal at rest position (as shown in  FIGS. 1A and 1B ) by the biasing torsion spring  18 , the abutment piece  17  is positioned to lie adjacent the head of a release pin  19 , which is mounted in respective receiving bores  20  of the mounting component  12 . The head of the release pin  19  is connected to an end of a pin release tether  21 . The lower loop  4  of the first length of webbing  2  is connected via a connector clasp  22  to a descent line  23 . The descent line  23  is fixed at its other end and is wound on a descent line drum  24 . 
     The descent line drum  24  is mounted to a support plate  25 . A brake device  26  is also mounted to the support plate  25 . The brake device  26  is coupled to rotation of the descent line drum  24 , by means of a gear arrangement comprising a main gear  27  which rotates with the brake device  26  and is connected to a brake pinion gear  28  by means of an idler gear  29 . As the brake device  26  rotates to deploy the descent line  23 , the brake pinion gear  28  is activated by the main gear  27  in order to brake the rotation of the descent line drum  24  and slow deployment of the descent line  23 . 
     As shown in  FIGS. 1A and 1B , when the rescue descender device  1  is ready for use, it is in the configuration shown. The webbing loop harness connector  16  is connected to the users harness and the upper loop  3  is connected via the safety line  36  (for example a standard self retracting lifeline) to an anchor point. In this way the user is securely anchored to an anchor point via the rescue descender device  1 . In this configuration, the release pin  19  cannot be removed from the receiving bores  20  of the load arm mounting component  12 . This is because the abutment piece  17  of the pivoting load arm  13  is positioned adjacent the head of the release pin  19  and prevents removal of the release pin  19 . In the embodiment shown the torsion spring  18  biases the pivoting load arm  13  to this ‘normal’ position, although the shape of the pivoting load arm  13  is such that the pivoting moment normally biases the pivoting load arm  13  to this position under gravity in any case. In this configuration the user can move about their business unhindered, but the release pin  19  cannot be removed either intentionally or un-intentionally. 
     In the event of a fall arrest event, the rescue descender device  1  reconfigures from the position shown in  FIGS. 1A and 1B  to the position shown in  FIGS. 4A and 4B  via the intermediate position shown in  FIGS. 3A and 3B . As the user becomes suspended from the anchor point via the safety line  36  connected to the upper loop  3  of the first length of the binding webbing  2 , the intermediate webbing length  5  pulls up on the series of movable bars  11  causing the movable bars  11  to slide upwardly and pinch the intermediate webbing length  5  securely. This ensures that the intermediate webbing length  5  and the movable bars  11  are held fast. The main upward force acts via the lowermost of the movable bars  11  and the intermediate binding webbing length  5  which is wrapped around the lowermost of the movable bars  11 . This configuration is shown in  FIGS. 3A and 3B . 
     Simultaneously, under the weight of the user now suspended from the anchor point, the pivoting load arm  13  pivots downwardly (arrow A). In so doing, the abutment piece  17  of the pivoting load arm  13  pivots out of its blocking position adjacent with the head of release pin  19 . Therefore once the fall arrest event occurs and the pivoting load arm  13  is loaded by the user—s suspended weight, the abutment piece  17  moves such that the release pin  19  can be pulled out of the receiving bores  20  of the load arm mounting component  12 . 
     In the embodiment the release pin  19  can only be removed from its home position secured in the receiving bores  20  of the load arm mounting component  12  when the pivoting load arm  13  is moved from its normal position. Furthermore the arrangement ensures that the pivoting load arm  13  moves from its home position automatically as a result of a fall arrest event. The pin release tether  21  is connected to the release pin  19  and has an end accessible to be pulled by the user to enable the release pin  19  to be removed when ready. 
     As shown in  FIGS. 6A to 6C  the release tether  21  can be secured within a pack or enclosure mounted on or with the harness  30  ready for use. In the embodiment shown the release tether is secured to a shoulder strap  30 a on the front of the user and a finger grip toggle  31  is connected to the tether line  21  to be pulled by the user in order to release the release pin  19 . The tether line  21  is provided with a Velcro type band  32  to secure to the shoulder strap  30   a . An over cover  33  is provided to prevent accidental release. In a preferred embodiment the tether line  21  can be provided with a second pull formation  37  in addition to the finger pull toggle  31 . The second pull formation  37  is a rigid or semi-rigid ring (such as a ‘D’ ring) secured in position on the tether line  21 . The second pull formation  37  is in use positioned to stand proud of, or project from, the shoulder strap of the harness adjacent the shoulder, torso or back of a user. The second pull formation  37  is shown in  FIGS. 6A   6 B  6 D (but omitted from  FIG. 6C ). In use the second pull formation  37  can be accessed remotely from the user, for example by means of hook rod used from above, in order to pull the release tether line remotely from the user. This enables the user to be lowered using the decent device actuated from a remote position. 
     Once the user has fallen and his fall has been arrested, he is suspended by the device  1  which is attached to the harness  30  on the back of the user. As shown in  FIGS. 6C and 6D , when the user is ready he opens the over cover  33 , peels back the band  32  and pulls on the pin release tether  21  to remove the release pin  19  from its home position. The resultant operation is shown in  FIGS. 5A and 5B . The release pin  19  releases from the lower loop  4  of the first length of the binding webbing  2 . As a result of releasing the lower loop  4  of the first length of webbing, the lower loop  4  can drop down releasing the tension on the intermediate webbing length  5  wound around the lowermost one of the movable pinch bars  11 . As a result the series of movable bars  11  can drop downwardly (see the arrows in  FIG. 5B ) becoming spaced out on the U shaped frame  7 . The intermediate webbing length  5  is no longer bound fast by the movable pinch bars  11  and as a result the intermediate webbing length  5  can feed through the pinch bars  11  in an upward direction of the U shaped frame  7 . 
     The closed end of the lower loop  4  catches on the connector clasp  22  and pulls the connector clasp  22  through the movable bars  11  along a serpentine path in an upward direction of the U shaped frame  7 . In so doing the descent line  23  is also pulled from the descent line drum  24  along the same path. As a result loop  2  moves away from the U shaped frame  7 , and the U shaped frame  7  and the user attached via the webbing loop harness connector  16  descends relative to the upper loop  2 .  FIGS. 4A and 4B  show the connector clasp  22  pulled completely through the U shaped frame  7  and bars  11  together with the upper end of the connector clasp  22 . The brake device  26  acts to slow the rate of descent in accordance with a preset desired descent rate. 
     In this embodiment, the release pin  19  is not a primary load supporting member of the rack restraint device  6 . The main vertical load is taken up by the intermediate webbing length  5  folded under the lowermost pinch bar  11 . The length  5  is clamped between the pinch bars  11 , such that the downward pulling force exerted by the loop  4  on the pin  19  is negligible when compared with the impulse weight or force as a result of the suspended user. 
     Accordingly the force required to remove the pin  19  (when the abutment piece  17  is moved clear of the path of the release pin  19 ) is sufficiently low to enable the user to remove the pin  19  manually by pulling on the release pin tether  21 . The pivoting load arm  13  moves automatically as a result of the load applied by the suspended user to clear the abutment piece  17  from obstructing removal of the release pin  19 . The load of the suspended user imparted between the length of webbing  2  (connected to the safety line  36 ) and the descender device is not transmitted primarily via the release pin  19 . The load on the release pin  19  is substantially independent of the load imparted by the suspended user. 
     The first length of webbing  2  is connected to the descent line  23  by the clasp  22 . These can be considered effectively as a single line as they act as such when deployed. The webbing  2  is connected to the safety line  36 . 
     Referring now to  FIGS. 7A to 9B , there is shown an alternative embodiment of the invention. 
     In the arrangement shown in  FIGS. 7A to 9B  the restraint device  6  of the first embodiment having the U shaped frame  7  with the bars  11  movably mounted on the limbs  8  is replaced by a cam action restraint device  56 . The cam action restraint device  56  comprises a cam actuator  57  which is mounted to a support plate  58  by means of a pivot pin  59  mounted between limbs  60 . A length of descent line  61  extends in the channel defined between the limbs  60  past the position of the pivot pin  59  and the cam actuator  57 . The cam actuator  57  has a length of descent line  61  extending radially with respect to an arcuate slot  63 . The length of descent line  61  receives the pivot pin  59 . The arcuate slot  63  receives the release pin  64 . The cam actuator  57  is provided with a serrated grip zone  65  for biting into the length of descent line  61  to clamp the length of descent line  61  fast against the  38 . 
     The cam action restraint device  56  is provided with a pivoting load arm  66  corresponding to the pivoting load arm  13  of the first embodiment, which has projecting abutment pieces  67  corresponding to the abutment piece  17  of the first embodiment. The abutment pieces  67  act to prevent removal of the release pin  64  from the arcuate slot  63  until the load is applied to pivot the pivoting load arm  66  as a result of a fall (in a similar means to operation of the first embodiment). The arrangement of this embodiment is set up for use by arranging the cam action restraint device  56  in the configuration shown in  FIGS. 7A to 7C . In this position, presence of release pin  64  in the arcuate slot  63  ensures that the cam actuator  57  pivots about the end of the eccentric slot  62  closest to the arcuate slot  63 . In so doing when the length of descent line  61  is pulled upwardly by a load, acting in the direction of arrow Z (as shown in  FIGS. 8A to 8C ), the cam actuator  57  tends to pivot to become increasingly engaged with length of descent line  61 , ensuring that the clamping grip against support plate  58  is increased. 
     The arcuate slot  63  permits pivoting of the cam actuator  57  about the pivot pin  59  to a limited arc. In this way increasing load on the length of descent line  61  results on an increasingly secure grip of length of descent line  61  against support plate  58 . In the set up position, the pivoting load arm  66 , which is connected to the users harness, is biased to a position in which one of the abutment pieces  67  are positioned adjacent the end of the release pin  64 , preventing the release pin  64  from being removed from its position within arcuate slot  63 . 
     When the user falls and the fall is arrested, the pivoting load arm  66  pivots to a release position under the load applied by the user suspended from the length of descent line  61 . This is the position shown in  FIGS. 8A to 8C . This happens in a similar manner as for the first embodiment. In so doing, the abutment piece  67  moves clear of the release pin  64  and no longer acts as an obstruction to removal of the release pin  64  from the arcuate slot  63 . The user can pull on a release pin tether  68  which is connected to the release pin  64  in order to pull the release pin  64  completely out of the arcuate slot  63 . In so doing, cam actuator  57  is able to move away from the length of descent line  61  and the support plate  58  and the clamping grip of the cam actuator  57  against the support plate  58  is released. The eccentric slot  62  moves with respect to the pivot pin  59  from the clamping position shown in  FIGS. 7 and 8  to a release position shown in  FIGS. 9A and 9B . The cam actuator  57  is free to rotate to the release position as shown in  FIGS. 9A and 9B . In this position, the length of descent line  61  can pas through the cam action restraint device  56 . 
     The length of descent line  61  can extend completely through the device and be connected at an upper end to the safety line and wound below the cam action restraint device  56  onto a storage reel (such as the reel  24 ). Up-line and down-line of the cam action restraint device  56 , the descender device can be in accordance with the first described embodiment. Accordingly when the cam action restraint device  56  has been released to the configuration of  FIGS. 9A and 9B , the length of descent line  61  can be wound from the descent line drum  24  along the path through the cam action restraint device  56 . The brake device  26  acts to slow the rate of descent in accordance with a preset desired descent rate. 
     In this embodiment, the release pin  64  is not a load supporting member of the cam action restraint device  56  and accordingly the force to remove the pin  64  (when the abutment piece  67  is moved clear of engagement with the release pin  64 ) is sufficiently low to enable the user to remove the pin  64  manually by pulling on the release pin tether  68 . The pivoting load arm  66  moves automatically as a result of the load applied by the suspended user to clear the abutment piece  67  from obstructing removal of the release pin  64 . The load of the suspended user imparted between the length of descent line  61  and the descender device  56  is not transmitted primarily via the release pin  64 . The load on the release pin  64  is independent of the load imparted by the suspended user. 
     Referring now to  FIGS. 10 to 13B , there is shown a further embodiment of a descender device  101 , which is similar in general terms to the device  1  of  FIGS. 1 to 5 . In this embodiment a restraint rack device  106  has a U shaped frame comprising spaced limbs  108  and two pinch bars  111  which are slidably mounted on the limbs  108 . The main difference of this embodiment over the first described embodiment is in relation to the connection between the binding webbing  102  and the descent line  123 . 
     In the previously described embodiment the lower loop  4  of the binding webbing  2  was secured to the upper end of the descent line  23  by means of the clasp  22 . This requires the clasp  22  to be pulled through the bars  11  when the descent line is being deployed. In practice the clasp can foul or become trapped resulting in non-ideal deployment or even malfunction. 
     In the embodiment of  FIGS. 10 to 13B , the binding webbing  102  and the release line are connected at a D ring  170  which is positioned downstream of the restraint rack device  106  and which therefore does not need to be pulled through the rack during deployment of the release line  123 . The upper portion of the release line  123  is threaded serpentine fashion through the pinch bars  111 . The binding webbing is likewise threaded serpentine fashion through the pinch bars  111  and the lower loop  104  is secured about a release pin  119  which is secured in a cradle  118  provided on a platform  112  by means of a breakable clip  171 . The platform  112  is provided with mounting apertures top enable mounting on the limbs  8  and is secured in position the rack frame device limbs  108  by means of a pin  175  passing through bores  181 , and also the mating plugs  185 . The swing arm  113  is pivotally mounted on the plugs  185  and provides for securing to the users harness. 
     As shown most clearly in  FIG. 11B , the release pin  119  is secured by the breakable clip  171  in a specific orientation in the cradle  118 . When the device is loaded as a result of a fall arrest event, the binding webbing  102  is pulled tight resulting in the pinch bars  111  being pulled upwardly towards the top of the rack device  106 . The release line  123  is pinched by the pinch bars preventing the release line  123  from being pulled through the device. In the loaded condition, the loop  104  of the binding webbing  102  is secured over the release pin  119 . The webbing  102  extends downwardly from the pin  119  via an opening  190  in the cradle  118 . Therefore in the loaded condition, the tension in the webbing  102  tends to securely hold the release pin  119  in the cradle. The end of the pin  119  rests on a ledge  195  adjacent the opening  190 . When the user is suspended and wishes to deploy the release line  123 , the user tugs sharply on the release pin tether  121 . In doing so the release pin ruptures the clip  171  and pivots from the position shown in  FIG. 10B  to the position shown in FIG.  1 lB. In the position shown in  FIG. 12  the end of the release pin  119  is no longer supported on the ledge  195  and the downward force acting on the pin by means of the loop  104  causes the loop  104  to be pulled downwardly off the end of pin  119  and through the opening  190 . In so doing the binding action exerted by the binding webbing  102  on the pinch bars  111  is released and they are able to move apart on the limbs  108 . This enables the binding webbing  102  and the release line  123  to be drawn simultaneously through the pinch bars  111 . This situation is shown in  FIGS. 13A and 13B . 
     A variation on this theme is shown in the embodiment of  FIGS. 14A to 14C , in which like items are referred to with the same reference numbers as the previous embodiment of  FIGS. 10 to 13B . In this embodiment the opening  190  is replaced by a slot  290  downwardly through which the end loop  104  of the binding webbing  102  is pulled when the release pin breaks free from the clip  171 . A guide frame  199  is provided for the release pin tether  121  in order to ensure that the release pin is pulled from the correct direction to effect release.

Technology Category: 1