Abstract:
The apparatus is a trapped key safety interlock device for use with a coupling that comprises a body provided with a face seal, a rim on one side and a projecting spur on the diametrically opposite side. The safety device includes a coupling part ( 201 ) which is complimentary to the said coupling ( 102 ) and which comprises a body portion having a rim portion ( 207 ) on one side for engagement with the spur of the said coupling and having a spur portion ( 206 ) on the diametrically opposite side for engagement with the rim of the said coupling ( 102 ). The rim portion accommodates a release mechanism ( 16, 18 ) for selectively enabling and disabling a key retention mechanism within the device. The key retention mechanism has a key retention condition and a key releasable condition, wherein the release mechanism comprises a primary release mechanism ( 16 ) and a secondary latching mechanism ( 18 ) resisting movement of the primary release mechanism until it is actuated itself. The method uses this apparatus as the safety device can prevent a vehicle releasably attached to a loading bay by the safety interlock device from being driven away from the loading bay until released using the safety interlock&#39;s release procedure.

Description:
[0001]    This application claims the benefit of United Kingdom Patent Application Serial No. 1504884.6, filed Mar. 23, 2015, which is hereby incorporated by reference in its entirety. 
       FIELD OF THE INVENTION 
       [0002]    This invention relates to an apparatus for preventing a vehicle from being driven away from a loading bay during loading/unloading, and a method for the same purpose. 
       BACKGROUND OF THE INVENTION 
       [0003]    The normal sequence of events at a loading bay is that a vehicle (a semi-trailer, a drawbar trailer, or a lorry) is driven up to a loading bay and the driver contacts staff in the building. The staff then open the loading bay for the driver. 
         [0004]    The loading bay has a door, usually of the ‘up and over’ type, and a dock leveler. The dock leveler is a powered ramp which is adjusted in height to accommodate differences in vehicle loading heights and to enable forklifts to drive from the building into the vehicle. 
         [0005]    There is a risk that if the trailer is allowed to pull away or move prematurely from these loading bays then the forklift could fall from the dock leveler. To prevent such accidents, or simply to prevent such premature vehicle departures, several safeguards are currently employed. These systems include:  
         [0006]    a) Traffic lights, some of which are linked to the dock leveler. This does not prevent the driver from moving off but relies upon him obeying the lights. These systems are quite expensive. 
         [0007]    b) A traffic barrier system which retains the vehicle at the loading bay until a barrier is raised. This also relies upon correct procedure and is expensive. 
         [0008]    c) An inbuilt wheel blocking device which is installed in the ground at each bay and which is raised to prevent the vehicle from leaving until loading is complete. This is very expensive and also relies upon correct procedure to be effective. 
         [0009]    d) A wheel clamp which is fitted when the vehicle arrives and which provides a physical and visual barrier to indicate to the driver and he/she should not drive off. This also relies upon procedures and is cumbersome to operate. 
         [0010]    e) A trapped key safety interlock which actively prevents the vehicle from being driven away from a loading bay during loading/unloading, the apparatus comprising a safety device which is complementary to a coupling on the vehicle and which when fitted to the coupling prevents the vehicle from being driven away, e.g. by causing the air supply for the trailer&#39;s air brakes to be maintained in a fail (disconnected) condition—a condition in which the brakes are automatically engaged. Such a safety device is disclosed in, for example, EP1493620, the whole contents of which are incorporated herein by way of reference. 
         [0011]    The trapped key safety interlock system includes a locking device which is operable to prevent removal of the safety device from the coupling and which prevents removal of a key from the locking device until the locking device is so operated. Only then can the released key be used to operate a device, such as a switch or a door lock, to enable the use of a loading bay.  
         [0012]    This safety device system then further prevents removal of the key from the switch or door lock until that is operated to disable use of the loading bay (since a corresponding key interlock mechanism is provided at that location too). Therefore, only once the loading bay is disabled can that key be removed therefrom for then again unlocking the earlier mechanism that is causing the trailer&#39;s braking system to be engaged. 
         [0013]    This trapped key safety interlock system has now been widely adopted, but a potential breach of its interlock can occur if a user manually interferes with the internal locking mechanism of the device before locking it onto the trailer&#39;s coupling, thus freeing the key either without first engaging the vehicle&#39;s braking system or without first disabling the loading bay. 
         [0014]    The present invention therefore looks to provide a tamper resistant version of trapped key safety interlock. 
       SUMMARY OF THE INVENTION 
       [0015]    The present invention provides a trapped key safety interlock device for use with a coupling that comprises a body provided with a face seal, a rim on one side and a projecting spur on the diametrically opposite side, the safety device including a coupling part which is complimentary to the said coupling and which comprises a body portion having a rim portion on one side for engagement with the spur of the said coupling and having a spur portion on the diametrically opposite side for engagement with the rim of the said coupling, the rim portion accommodating a release mechanism for selectively enabling and disabling a key retention mechanism within the device, the key retention mechanism having a key retention condition and a key releasable condition, wherein the release mechanism comprises a primary release mechanism and a secondary latching mechanism resisting movement of the primary release mechanism until it is actuated itself.  
         [0016]    Preferably the device comprises a key releasably locked within it. The key might instead be released but releasably lockable within it. The device might then be mounted on the coupling. 
         [0017]    Preferably the secondary latching mechanism comprises a sprung member. 
         [0018]    It is preferably located such that it is engaged by the spur of the coupling before the primary release mechanism. 
         [0019]    Preferably the secondary latching mechanism comprises a sprung plate. The sprung plate may be indirectly acted upon by the spur, such as via a captured ball bearing (a ball bearing behind a smaller hole). The ball bearing should preferably be acted upon by the spur of the coupling before the primary release member. 
         [0020]    Preferably the sprung plate is a split sprung plate, having two separately moveable components. Preferably each component underlies a ball bearing. Both ball bearings can thus then be acted upon by the spur. Preferably only one of them pushes down a release mechanism to release the primary release mechanism. 
         [0021]    Preferably the primary release mechanism is a pivotal release mechanism. However, it might instead slide. 
         [0022]    Preferably it is sprung into a non-releasing condition, thus ensuring the key is trapped until released. 
         [0023]    Preferably the primary release member is a pivotal latching member. It is preferably mounted on a pivot pin. 
         [0024]    Preferably the primary release member has a latch on an underside of it. The latch might be on a projecting foot or extending member of the primary release member.  
         [0025]    The primary release member preferably has a flange towards its rear for moving into or out of engagement or alignment with a stub of a rotatable member—rotatable using the key. The flange is moved upon actuation of the primary release member into a position that allows rotation of the rotatable member. 
         [0026]    Preferably the safety device has an outer casing. Preferably the outer casing is fixed relative to the coupling part. It might be removable for servicing purposes. 
         [0027]    Preferably the key is arranged to operate an inner sleeve or inner element relative to the outer sleeve to close a port or window provided in the outer sleeve when the key is rotated into a key release condition. The inner element might be a door. Preferably the door is made of metal to resist tampering. 
         [0028]    The invention also provides a method of preventing a vehicle from being driven away from a loading bay during loading/unloading, comprising the sequential steps of: 
         [0029]    applying to a vehicle at a loading bay a safety device which prevents the vehicle from being driven away from the loading bay; 
         [0030]    locking the safety device to prevent removal of the safety device, by means of a key which is prevented from being removed from the safety device until the safety device is locked; 
         [0031]    removing the key from the locked safety device; and 
         [0032]    using the key to enable use of the loading bay, thus simultaneously trapping the key in a second interlock mechanism so that it cannot be used to unlock the safety device, the key remaining so trapped until it is used to disable use of the loading bay, the safety device being the trapped key safety interlock device described above.  
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0033]    The invention will now be described in further detail, by way of example only, with reference to the accompanying drawings, in which: 
           [0034]      FIG. 1  is a schematic side view of a loading bay; 
           [0035]      FIG. 2  is a schematic side view of the loading bay in use with a trailer unit; 
           [0036]      FIG. 3  is a perspective view of a door lock for the door of a loading bay; 
           [0037]      FIG. 4  is a schematic side view of part of an articulated vehicle, showing thereon a standard “glad hand” or “palm” coupling assembly; 
           [0038]      FIG. 5  is a plan view corresponding to  FIG. 4 ; 
           [0039]      FIG. 6  is a longitudinal section through a prior art safety device as described in EP1493620, for use with the type of coupling shown in  FIGS. 4 and 5 , before fitting to the glad hand coupling; 
           [0040]      FIG. 7  is a longitudinal section through the safety device of  FIG. 6  after the safety device has been fitted to the glad hand coupling and a key has been turned to lock the safety device; 
           [0041]      FIG. 8  shows a perspective view of a preferred embodiment of safety device of the present invention; 
           [0042]      FIG. 9  shows the embodiment of  FIG. 8  with the outer cover removed; 
           [0043]      FIG. 10  shows an internal cutaway view of the preferred embodiment showing a modified trigger or pivotal latching member;  
           [0044]      FIG. 11  shows a sectional side view of the trigger and its associated secondary latching member; 
           [0045]      FIG. 12  shows a front elevation of the new trigger; 
           [0046]      FIG. 13  shows a reverse side perspective of the trigger, showing an interaction of the back of the trigger with a stub of a key activated turnable mechanism—linked to a door of the safety device; 
           [0047]      FIG. 14  shows the new safety device being connected onto a coupling of a trailer; 
           [0048]      FIG. 15  shows a cutaway view of the coupling and safety device from a different angle; 
           [0049]      FIG. 16  shows the engagement with the coupling almost complete, again in cutaway view; 
           [0050]      FIG. 17  shows the arrangement once the key has been turned and removed from the safety device, again in cutaway view; and 
           [0051]      FIG. 18  shows the locked safety device on the coupling, with the key removed and the door closed. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0052]    Referring first of all to  FIGS. 1 and 2  there is shown a schematic view of a loading bay  51  including a switching device  52  for selectively enabling and disabling the use of the loading bay, the switching device including a lock  53  that is operable by a key  39  from  a safety device such as an interlock device (see  FIGS. 6 and 7  for a prior art device and  FIGS. 8  onwards for a device according to the present invention). 
         [0053]    The switching device  52  will be a standard key interlock mechanism, and as such the key  39  will become trapped by the lock  53  upon activation of the loading bay until the lock is turned again to disable use of the loading bay  51 . 
         [0054]    One way of enabling/disabling the loading bay is for this switching device  52  to enable and disable a drive or power source for operating a dock leveler  54 . 
         [0055]    Referring then to  FIGS. 4 and 5 , coupling assemblies fitted in the air supply for trailer braking systems allow air under pressure to be supplied to the brake system of the trailer to release a braking device on the trailer unit of an articulated vehicle. In the event that the air supply fails, the braking device is automatically engaged to prevent movement of the trailer unit (or to brake the moving trailer unit). 
         [0056]    A preferred procedure for loading a trailer unit  57  ( FIG. 2 ) using the above-described safety device  11  will now be described: 
         [0057]    1) The driver of the articulated vehicle with the trailer unit  57  arrives in the vicinity of the loading bay  51  and reverses towards the dock leveler  54 . The driver gets out of the tractor unit, walks to the back of the trailer unit  57 , and opens its doors. 
         [0058]    2) The driver contacts a warehouse operative, who walks back to the tractor unit with the driver, bringing with him a safety device in which the key  39  is trapped. That key will have been removed from the thereafter disabled switching device  52 , and it is retained in the safety device by a key retention device, such as that of any of  FIGS. 6 to 18 .  
         [0059]    3) The driver then reverses the vehicle further until the trailer unit  57  is at the loading bay  51  (preferably in contact with a buffer  58 ), unless of course it was already so positioned. 
         [0060]    4) The driver then disconnects a “glad hands” coupling  71  ( FIGS. 4 and 5 ) between the trailer and the tractor/cab, thereby disconnecting the brake supply line for his vehicle/trailer, with the result that the brakes of the trailer unit  57  engage, or lock on. 
         [0061]    5) The warehouse operative then fits the safety device onto the appropriate half  102  of the glad hands coupling  71  and turns the key  39  to secure the safety device onto the coupling  102 , and removes the key  39 , thereby preventing removal of the safety device until the key is reapplied and turned. Re-connection of the air supply to the emergency braking device (the only way to release the brakes) is thus prevented. 
         [0062]    6) The operative then inserts the key  39  into the lock  53  of the switching device  52  and turns it. This enables operation of the dock leveler  54 . (In addition, this may enable operation of the bay door  56  and/or turn a traffic light  59  from green to red.) 
         [0063]    7) Loading or tipping then commences. Meanwhile, the tractor unit of the vehicle can be driven away, if desired. 
         [0064]    In the example shown in  FIG. 2  the trailer unit  57  is a semi-trailer, which is temporarily supported by a frame  61 . 
         [0065]    8) When loading or tipping has been completed, the switching device  52  is turned off and disabled by turning the key  39 , which is then released from the lock  53  and can be used to unlock the safety device  11  from the coupling at the trailer. Removal of the safety device  11  from the coupling  102  then allows the air supply to be reattached to the brakes, thus releasing the emergency brake and thus allowing the trailer unit  57  to be driven away.  
         [0066]    In the preferred embodiment the switching device  52  utilises a so-called figure lock, which is a commercially available product in which a rotatable central member has raised symbols  47 . See  FIG. 3 . These mate with the key  39  which has an engraved form matching the symbols. When the central member is rotated by the key  39  to the unlocked or operation position, the key  39  is trapped in the lock  38 . When the central member  46  is rotated by the key  39  to the position corresponding to the key release position, the key  39  can be released from the lock  38  and is therefore free for use with the safety device for locking on the brakes of the trailer. 
         [0067]    A similar figure lock is provided on the safety device. 
         [0068]    Other key or lock forms are also useable with this system, such as conventional keys, albeit fitted with mechanisms for interlocking to the lock unit. 
         [0069]    The switching device  52  shown in  FIG. 1  could be replaced by a door lock  62  ( FIG. 3 ) which is operable by the key  39  and which has a bolt  63  for securing the door  56  of the loading bay  51 . The key  39  cannot be released from the door lock  62  until the key  39  has been turned so as to secure the door  56 , thereby disabling the loading bay. 
         [0070]    In another embodiment the door lock may trap a second key, which is released when the first key  39  is turned to unlock the door and which can only then be used to operate an electrical switch, e.g. controlling the supply of power to the dock leveler  54 . This could be a second key—different to the first, thus preventing the key for operating the dock leveler being released to the driver, even in a secured state, until the brakes are locked on. 
         [0071]    Alternatively, the door lock may be combined with such a switch. 
         [0072]    In another embodiment the key  39  may be used to operate a lock on a communication box providing communication through a wall separating the inside of the  loading bay from the outside. The driver inserts the key  39  in the external lock and turns it, thereby trapping the key  39 . This action is communicated (electrically or mechanically) to an internal lock, which thereupon releases a second key, for use by an operator in the loading bay, thereby enabling use of the loading bay. The first key ( 39 ) remain trapped until the operator inserts the second key into the internal lock and turns it, thereby trapping the second key. This procedure obviates direct contact between the driver and the operator. 
         [0073]    The standard coupling assembly  71  shown in  FIGS. 4 and 5  is (according to International Standard ISO 1728) in the supply line (emergency line) which supplies air under pressure to release the braking device on the trailer unit  57 . The assembly  71  comprises a first coupling  101  on the end of a flexible hose  72  extending from the tractor/cab. It constitutes a first supply line section on the tractor unit  73 . A second coupling  102  on the end of a second supply line section  74  is provided on the trailer unit  57 . 
         [0074]    Each coupling  101 ,  102  comprises a body  76  carrying a face seal. One of these bodies is shown in dotted lines in  FIG. 7 —the one  102  on the trailer&#39;s pipe. Another is shown in  FIG. 14  onwards, again the one  102  on the trailer&#39;s pipe. 
         [0075]    The two couplings  101 ,  102  are connected by placing their face seals in mutual contact and rotating them about their common axis until a spur  79  of each coupling engages under a rim  78  of the other coupling so that the face seals are clamped hermetically together. The relative motion of the complementary couplings  101 ,  102  resembles the rotation of one hand palm against the other, so this type of coupling is commonly referred to as a “palm” coupling or a “glad hand” coupling. 
         [0076]      FIGS. 6 and 7  show a prior art safety device of this type. It comprises a coupling part  201  which is complementary to the second coupling  102  (described above) and projects in the axial direction from a generally cylindrical inner part or body  202  which is surrounded by a generally cylindrical outer part or sleeve  203 . The coupling part  201  comprises a body portion  204  shaped so as to be complementary to the body  76  of the second  coupling  102 , a spur portion  206  for engagement with the rim  78 , and a rim portion  207  which is to engage the spur  79  and which is connected to the inner body  202 . 
         [0077]    The outer sleeve  203  is axially slidable relative to the inner body  202  between a first position ( FIG. 6 ), in which the coupling part  201  is exposed for connection to the coupling  102 , and a second position ( FIG. 7 ), in which the sleeve  203  covers the body part  204  (and also the body  76  of the coupling  102 ) to prevent disconnection of the coupling part  201  from the coupling  102 . 
         [0078]    The inner body  202  carries a figure lock  208  operated by a key  39  as described above. The lock  208  has a locking member  209  which is rotatable (by rotation of the key  39 ) between a locking position in which it engages in an annular internal recess  211  in the sleeve  203  to retain the sleeve in its second position ( FIG. 7 ), and an unlocking position ( FIGS. 6 ). In the latter position the key  39  is trapped in the lock  39 . Furthermore, the sleeve  203  when in its first position ( FIG. 6 ) hinders access to the trapped key  39  and also interferes with the key  39  so as to prevent it from being turned to a position in which it is free. 
         [0079]    The inner body  202  and the coupling part  201  define a diametral slot  212  which accommodates a latching plate  213  guided and retained by pins  214  engaging in elongate cut-outs  216 . The plate  213  is urged by a compression spring  217  into a latching position ( FIG. 6 ) in which it engages in an annular internal recess  218  in the sleeve  203  in the first position, thereby preventing the sleeve from being moved to the second position ( FIG. 7 ), which would allow the key  39  to be freed. When the coupling part  201  is connected to the coupling  102 , the spur  79  acts on an extension  219  of the latching plate  213  so as to move the plate  213  out of engagement with the recess  21 , thereby allowing the sleeve  203  to be moved to its second position ( FIG. 7 ). 
         [0080]    The sleeve  203  is provided with a carrying handle  221  which is pivotable between the positions shown in  FIGS. 26 and 27  respectively. The sleeve  203  is freely  rotatable about its own axis relative to the inner body  202 , in both the first position ( FIG. 6 ) and the second position ( FIG. 7 ). 
         [0081]    The above mechanism is modified by the present invention so as to prevent the key&#39;s removal being achievable on a non-fitted safety device (with a locked-in key) simply by pushing a finger through an open front end and depressing the extension  219  of the latching plate  213 . This is achieved by adding a secondary latching member within the rim portion that has to be actuated prior to the extension itself being depressible. 
         [0082]    Referring now to  FIGS. 8 to 18 , a preferred embodiment of the present invention is described. 
         [0083]    As can be seen, as with the previous safety device, this safety device comprises a coupling part  201  which is complimentary to a glad hands coupling  102  (see  FIGS. 14 to 18 ) and which project in a generally axial direction from a generally cylindrical outer casing or outer part  203 . In this embodiment, however, the outer part or casing  203  is fixed relative to the coupling part  201 , rather than being slidable when released. 
         [0084]    The outer part  203  has a window  10  which can be opened or closed by an internal door  12 , which door is operated by a key  38 , which key in this embodiment is as per the previous embodiments. Keys other than figure keys may instead be used, as before. 
         [0085]    The window  12  allows the safety device  11  to be fitted onto the second coupling  102  since the window aligns with an area  14  above a rim portion  207  of the safety device&#39;s coupling part  201 . 
         [0086]    The safety device  201  further has a spur portion  206  much as in the previous product. 
         [0087]    The rim portion  207  is also now modified to comprise not just a latching plate  213 , but also a secondary latching member  18 . In this instance the latching plate is replaced by a pivotal latching member  16 . The secondary latching member  18 , however, is linearly actuated instead. It might instead be rotatable or pivotable. 
         [0088]    The secondary latching member  18  is provided to resist activation of the pivotal latching member  16  until it has itself been interacted upon by the rim of the second coupling  102 . 
         [0089]    The secondary latching member  18  is shown to comprise a ball bearing in  FIG. 8 . There is a second ball bearing  18  as well. Only one of these are operational in this embodiment. The other is a dummy and provides no release function. However, by providing it, it provides symmetry to the appearance of the product. It further provides a bearing surface over which the spur of the second coupling can more easily glide, thus assisting with the smoothness of operation of the product thereon. 
         [0090]    Also for providing a smoothness of operation, an upstanding arcuate flange  20  is also provided—it provides a further support surface for the spur of the second coupling. 
         [0091]    The operational secondary latching member  18  is the one closer to the window in this embodiment. This can be more clearly seen in the breakaway views of  FIGS. 10  onwards. 
         [0092]    Referring first, however, to  FIG. 9 , a further view of the safety device  11  is provided, but this time with the outer part  203  removed. It is now possible to see an inner casing  22 . This inner casing houses and retains, via various bolts or screws or pins, the internal workings and body of the safety device. It too is fixed relative to the rim portion and spur portion.  
         [0093]    Referring next to  FIG. 10 , as can be seen the functional secondary latching member  18  has a ball bearing  24  mounted on a sprung plate  26 . The sprung plate  26  is stepped so as to have a high portion  28  and a low portion  30 . The low portion  30 , as seen in  FIG. 11 , has a rearward upstand  32 . This rearward upstand  32  is for bearing against a latch  34  of the pivotal latching member  16  so as to prevent actuation of the pivotal latching member  16  until the sprung plate  26  is driven downwards against the spring bias provided by a spring  36  (see  FIG. 10 ). Once it has been pushed downwards by the interaction of the ball bearing against the spur of the secondary coupling  102 , as shown in  FIGS. 15 and 16 , the rearward upstand  32  becomes located below the latch  34  on the base of the pivotal latching member  16 . Further insertion of the spur  79  can thus push down the pivotal latching member  16  at its extended end, thus rotating it about its pivot pin  42  for moving a flange  44  at a rear end thereof. This allows the key to turn since it moves the flange out of a blocking engagement with a stub  46  attached to the component that is rotated by the key  38 . This thus also then allows the key  38  to rotate the mechanism  48  of the lock to rotate the door  12  across the window  10  when the spur  79  has been fully rotated over the pivotal latching members extended end  219  and perhaps even over the second ball bearing  50 . 
         [0094]    Once the key has been turned, it is then free to be removed from the safety device for use on, for example, the switch of the loading bay. This then leaves the safety device securely locked onto the coupling  102 . 
         [0095]      FIG. 18  shows the door closed across that window. Because the door is closed, the safety device can no longer be rotated off the second coupling  102  until the key  38  is reinserted and unlocks the door. 
         [0096]    Because of the sprung secondary locking mechanism, e.g. the sprung ball bearings, it is less straightforward to insert something into the safety device to release the pivotal latching member—first the secondary latching member has to be released. The spring tension in the spring  36  for the sprung plate  26  can be made stiff enough to prevent a user using his finger to release the key. Likewise a spring for the pivotal latching member  can also be made adequately strong to prevent inadvertent release. That second spring  54  is provided toward the top of the pivotal latching member  16 . 
         [0097]    The locking sleeve or door is preferably made of hardened steel, or even titanium, to resist attack. Likewise the body and rim/spur portions can be made of metal, such as hardened steel, to ensure they are strong enough to resist attack. 
         [0098]    The above-described safety device is of relatively low cost and only requires the fitting of an interlocked switch in the power supply to the dock leveler. Its use ensures that the trailer unit cannot be moved until loading is completed. By physically interlocking the brakes of the trailer unit with the operation of the loading bay, reliance upon procedural compliance is avoided, eliminating the possibility of human error. No modification of the vehicle is required. 
         [0099]    Various modifications may be made to the safety device within the scope of the invention as defined by the appended claims. For example, it could be modified to suit other couplings. The safety device might even be used in a brake line other than the emergency line, e.g. in an auxiliary line. Furthermore, the figure lock  38  described above could be replaced by any suitable lock, in particular a high security lock to prevent theft of the trailer unit. 
         [0100]    It will also be appreciated that the safety devices described above are applicable not only to articulated vehicles but also to rigid vehicles, with suitable modification of the brake line.