Abstract:
The invention relates to a padlock in particular to a padlock for securing and monitoring a switch of an industrial plant. The invention further relates to a set of padlocks, to a padlock housing and to a method of retrofitting a padlock.

Description:
BACKGROUND OF THE INVENTION 
     The invention relates to a padlock in particular to a padlock for securing and monitoring a switch of an industrial plant. The invention further relates to a set of padlocks, to a padlock housing and to a method of retrofitting a padlock. 
     A particular area of application of a padlock is in the field of occupational safety. There is the risk in connection with the servicing of industrial plants, for example, of a production machine, that the industrial plant deactivated for the purpose of service work is activated again by accident while the servicing work is still continuing. A substantial danger for the service engineer can result from this. It is therefore customary that the service engineer moves a switch associated with the industrial plant to an OFF position for the duration of the service work and secures it in this position, i.e. the switch is directly blocked or access to the switch is blocked. The named switch is typically an energy supply switch, for example a main electrical switch of a control device or of an energy supply device of the industrial plant (e.g. power switchbox). Alternatively to this, the named switch can, for example, be a valve of a liquid line or of a gas line. 
     In order to effectively avoid an accidental activation of the industrial plant by another person, each service engineer hangs a padlock on the named switch or on a blocking device associated with the switch before starting his work and locks said padlock. The switch is hereby secured in its OFF position, i.e. the switch cannot be moved accidentally back into an ON position by another person. When the service engineer has ended his work, he unlocks his padlock again and releases it from the switch. Each service engineer usually has his own individual padlock (or a plurality of his own individual padlocks) associated with him. 
     This procedure is also called locking out. The padlock used is accordingly called a lockout lock. The document U.S. Pat. No. 5,449,867 shows such a securing of an electric rocker switch by means of a padlock. It is known from the document U.S. Pat. No. 3,171,908 to secure the position of a rotary switch by means of a padlock. 
     So that a plurality of service engineers can block and release the switch again independently of one another, a plurality of receivers (e.g. eyelets) can be provided at the switch for hanging a plurality of lockout locks. This is known from the document U.S. Pat. No. 6,388,213, for example. If only a single receiver for a lockout lock is provided, a securing claw can be used which is hung into the respective eyelet of the switch or of the associated blocking device and which in turn has a plurality of hang-in eyelets for a respective padlock. Only when the last padlock has been removed from the securing claw, the securing claw can be removed from the switch so that it can again be brought into the ON position. Such a securing claw for use at an electric switchbox is known, for example, from documents U.S. Pat. Nos. 6,396,008, 5,365,757 and 3,667,259. 
     It is known in connection with such a securing of a switch of an industrial plant to equip the lockout lock having a lock body used with a housing of plastic, with a shackle being displaceably held at the lock body and with a lock cylinder being arranged in the lock body. The lock cylinder can selectively be brought from an open position into a locked position to lock the shackle to the lock body after the shackle has, for example, been hung into an eyelet of the switch. By forming the lock housing from plastic, a particularly light padlock results which is of advantage in the use as a lockout lock since the service engineers occasionally carry a plurality of lockout locks simultaneously. A housing of plastic can also contribute to a desired electrical insulation. By the use of a plastic housing, there is furthermore a particularly simple possibility of color marking the padlock. Such a lockout lock having a housing of plastic is known, for example, from documents U.S. Pat. Nos. 7,278,283 and 5,755,121. 
     Depending on the specific application or use, a customer may desire different designs of the lockout lock. It may for example be necessary to have a relatively long lock housing so that identity pictures or photos can be applied to the lock housing and/or warning messages can be printed on the lock housing in multiple languages. Such a modification of the exterior of the lockout lock should, however, not necessarily affect its interior (i.e. the lock body, particularly the locking mechanism including for example a lock cylinder, an associated key and displaceable locking members). It is also desirable that such a change of the design may be carried out fast and easily by a locksmith or a service unit. The known padlocks, however, require an enormous investment in inventory to meet the market&#39;s expectations for fast delivery of special versions, due to the numerous possibly required versions (e.g. color, size, shackle engagement length, cylinder configuration). 
     SUMMARY OF THE INVENTION 
     It is an object of the invention to provide a padlock which enables a reliable securing of a switch of an industrial plant with a simple design, and which allows for an easy and fast change of the exterior of the padlock. 
     Particularly, it is an object of the invention to provide a padlock which has a relatively long housing and which can be produced by retrofitting a standard size padlock. It is another object of the invention to provide a padlock which minimizes the necessary inventory investment. 
     This object is satisfied by a padlock having
         a lock body defining first and second passages therein;   a shackle having first and second shanks linearly displaceable in the first and second passages between a locked position and a released position, the first shank being withdrawn from the first passage and the second shank being retained in the second passage in the released position;   a housing having a lock body reception space and a head space;       the housing comprising a reception groove at an outside thereof extending along the head space adjoining the first passage;   and the first shank at least partly overlapping the housing and being pivotable into and out of the reception groove about the second shank in the released position.   

     Such a padlock has a modular design which allows not only to exchange the lock body (including the locking mechanism) if necessary, but also the housing. Particularly, instead of a standard size housing of relatively short length a long housing may be used which for example has bilingual warning messages printed on its exterior. The padlock can be easily and quickly assembled from an existing padlock having a standard size housing and shackle by exchanging the housing and shackle, while optionally keeping the lock body if desired. As such, if a customer requires a padlock (particularly a lockout lock) having a relatively long housing, a locksmith or a service unit may simply provide an off-the-shelf or existing standard lock body with the housing according to the invention and an associated shackle. The padlock according to the invention and particularly its housing therefore in conjunction with standard size padlocks create a modular padlock system which allows an easy and fast modification of the padlock exterior design. 
     The housing including the reception groove can be manufactured very cheaply, particularly when the housing is made of plastic. For example, the housing can be made in an injection molding process. The associated shackle must be of corresponding length but can be of simple design. If an electrical insulation is desired for the use as a lockout lock, the shackle can be made of plastic, or the shackle can be made of a metal or a metal alloy having a plastic cover on the parts protruding from the housing during use. 
     As such, the invention minimizes the inventory investment and at the same time facilitates faster delivery of desired padlock configurations. 
     Moreover, by providing the housing with said reception groove a padlock is created which can only be opened by pivoting the padlock about the second shank in one direction. This also prevents the padlock from unnecessarily engaging plant parts when the lock is opened, since it cannot open about a full angle of 360° as is the case for prior art padlocks. 
     The padlock in accordance with the invention will be explained in the following only by way of example with reference to the drawings and by means of the dependent claims. 
     The invention further relates to a set of padlocks which comprise a first padlock, which is of prior art design, i.e. having a relatively short housing without a reception groove, and a second padlock having the herein described features. 
     The invention further relates to a padlock housing comprising:
         a lock body reception space for receiving a lock body and a head space; and   a reception groove at an outside of the housing extending along the head space for receiving a shank of a shackle of the padlock.       

     The invention further relates to a method of retrofitting a padlock, the padlock comprising a lock body defining first and second passages therein, a first shackle having first and second shanks linearly displaceable in the first and second passages between a locked position and a released position, and a first housing having a lock body reception space. The method comprises the steps of:
         removing the first housing and the first shackle from the lock body; and   mounting a second shackle and a second housing to the lock body;
 
wherein the second shackle is longer than the first shackle along an axis of the first passage; and wherein the second housing is longer than the first housing along the axis of the first passage, the second housing comprising a lock body reception space for receiving the lock body and a head space, and further comprising a reception groove at an outside of the second housing, wherein the reception groove extends along the head space and adjoins the first passage of the lock body.
       

     Further areas of applicability will become apparent from the description provided herein. It should be understood that the description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure. 
    
    
     
       DRAWINGS 
       The drawings described herein are for illustration purposes only and are not intended to limit the scope of the present disclosure in any way. 
         FIG. 1  is a cross-sectional view through the center of a padlock from the front in accordance with the invention; 
         FIG. 2  is a perspective rear view of the padlock; and 
         FIG. 3  shows a set of padlocks comprising a padlock in accordance with  FIG. 1  and a padlock having an identical interior and the same shackle engagement length (clearance) but a smaller sized standard housing. 
     
    
    
     DETAILED DESCRIPTION 
     The following description is merely exemplary in nature and is not intended to limit the present disclosure, application, or uses. It should be understood that throughout the drawings, corresponding reference numerals indicate like or corresponding parts and features. 
     Referring now to  FIG. 1 , where a section through a padlock  10  is illustrated. The padlock comprises a lock body  12 , a U-shaped shackle  14  and a lock actuator  18  that are secured within the lock body  12 . The lock body  12  is incorporated in a housing  20  and terminated at an end (bottom side) by a plastic bumper  22  of the housing  20 . The lock body  12  further defines first and second passages  28 ,  30 , within which respective first and second shanks  32 ,  34  of the shackle  14  are slidably disposed. 
     The first and second shanks  32 ,  34  include respective notches, which are selectively engaged by respective locking members  40 ,  42  or bolt drivers of the lock actuator  18  to inhibit axial movement of the shackle  14  in the direction A when the lock is locked. The first shank  32  is shorter than the second shank  34  and may be withdrawn from the first passage  28 . The second shank  34  is slidably disposed within the second passage  30  but can not be withdrawn therefrom. More specifically, a shackle retaining pin  44  of the lock body  12  extends into a blocking notch  46  defined within the second shank  34 . The blocking notch  46  defines the range of slidable movement of the second shank  34  within the second passage  30 . The shackle retaining pin  44  inhibits a removal of the second shank  34  from the second passage  30 . 
     A rotatable plug  60  secured with a plug retaining pin  62  is operably engaged with the lock actuator  18 . The plug retaining pin  62  also serves as a rotational abutment for the plug  60 , i.e. a so-called stop pin. A key  48  is insertable into a keyhole of the plug  60  to enable rotation of the plug  60  between a first position and a second position. In the first position, which is shown in  FIG. 1 , the plug  60  holds the lock actuator  18  in a locked condition. In the locked condition, the locking members  40 ,  42  of the lock actuator  18  engage the notches of the first and second shanks  32 ,  34  of the shackle  14 , thereby inhibiting axial movement of the shackle  14  in the direction A. In the second position, the plug  60  holds the lock actuator  18  in an unlocked condition (not shown). In the unlocked condition, the locking members  40 ,  42  of the lock actuator  18  retreat from the notches of the first and second shanks  32 ,  34 , enabling the shackle  14  to move in the direction A (and vice versa) by a distance X defined by the shackle retaining pin  44  and the blocking notch  46  of the second shank  34 . During the assembly of the padlock  10  the retaining pin  44  is only introduced into the lock body  12  in a loose manner as will be discussed in the following. 
     When the key  48  is turned to open the lock (not shown) it actuates the lock actuator  18 . A series of cylindrical pins  52  respectively biased with respect to a pin hole cover  84  via pin springs  54  permit the movement of the plug  60  via the key  48  only if bottom pins  56  align the cylindrical pins  52  at a shear line permitting movement of the plug  60  and hence of the lock actuator  18 . 
     As can be seen from  FIG. 1  the housing  20  is of generally rectangular shape and is preferably made of plastic, as this is an electrically insulating and light weight durable material, which can be provided in a multitude of colors in a simple injection molding process. The different colors enable a color coding between different locks  10  and machine parts or operating/servicing personal (not shown). 
     In addition to housing the lock body  12  in a lock body reception space  64 , the housing  20  further comprises a head space  66  at its end  68  housing the second shank  34  of the shackle  14 . This means that a volume of the housing  20  between the lock body  12  and the end  68  (i.e. the top side) of the housing  20  is referred to herein as the head space  66 . For this purpose second shank  34  is guided within the head space  66  between the second passage  30  and the end  68 . The first shank  32  is guided in a reception groove  72  ( FIG. 2 ) arranged at an outside of the housing  20  in the region of the head space  66  adjoining the first passage  28 . In particular, the reception groove  72  is arranged at a corner of the housing  20 . The reception groove  72  extends coaxially with the first passage  28  and is parallel to the second passage  30  of the lock body  12 . 
     In the unlocked state of the padlock  10 , i.e. when the locking members  40 ,  42  are retracted from the notches, the shackle  14  is slid upwardly (with respect to the drawing, it can naturally also slide in any direction A in which the padlock  10  is pointing in use) whilst the second shank  34  is retained in the housing  20  by means of the shackle retaining pin  44 . The distance X the shackle  14  is displaced in the direction A would actually be too small for allowing the pivoting of the first shank  32  about the second shank  34  since the first shank  32  still partly overlaps the housing  20  and the first shank  32  would thus still be stuck within the housing  20 . Accordingly, if the reception groove  72  were not provided, the padlock  10  would not function. 
     The shackle  14  and the lock body  12  are generally of metal or a metal alloy. For example, the lock body  12  can be formed by aluminum or an aluminum alloy to save weight. As can be seen from  FIG. 1  the shackle  14  is at least partly covered with a plastic casing  76  at least in an external region of the padlock  10 , i.e. those parts of the shackle which in the locked state of the padlock are visible. The plastic casing  76  is provided to additionally electrically insulate the shackle  14 . 
     The housing  20  has a length which is at least substantially defined by the sum of a length of the lock body reception space  64  and a length of the reception groove  72 . In practice one would normally select the length of the reception groove  72  to correspond to at least 20% of a length of the housing  20  and to at most 80% of a length of the housing  20 . Other lengths are naturally possible, provided at least a part of the first shank  32  is still received by the reception groove  72  in the released state. In the example of  FIG. 1  length of the reception groove  72  corresponds at least substantially to the length of the lock body reception space  64 . 
     A shank  32 ,  34  is herein defined as a limb of the shackle  14 , the length of the shank  32 ,  34  being defined as the dimension extending from a free end of the shank to the start of the curvature of the shackle  14 . 
       FIG. 2  shows a perspective rear view of the padlock  10  with an installed shackle  14  in the locked position. One can clearly see the reception groove  72  into and out of which the first shank  32  of the shackle  14  is pivoted in use in the released state of the padlock  10 , and which also allows a rectilinear movement of the first shank  32  of the shackle  14  along the direction A for inserting the first shank  32  into the first passage  28  of the lock body or for withdrawing the first shank  32  of the shackle  14  from the first passage  28 . 
     It also becomes clear from  FIG. 2  that the front side of the housing  20  (hidden in  FIG. 2 ) has a large surface not affected by the reception groove  72 . The large surface of the front side of the housing  20  offers enough space, for example, to print warning messages on the padlock  10  in multiple languages or to apply an identity photograph. 
     The invention also relates to a set of padlocks ( FIG. 3 ) comprising at least: a first padlock  110  and a second padlock  10  as herein described, the first padlock  110  including the same lock body as the second padlock  10 , but a smaller sized regular housing  120  and also a shorter shackle  114  (having first and second shanks  132 ,  134 ). In general, the set can include multiple padlocks having a variety of housing lengths and associated reception groove lengths and shackle lengths. Since the plastic housing  20  can be manufactured very cheaply and since also the manufacture of the shackle  14  does not require great expense, the set of padlocks according to  FIG. 3  can be provided based on the same type of internal lock body at low additional costs. As shown in  FIG. 3 , both padlocks  10  and  110  have the same engagement length or clearance of their respective shackles  14  and  114  when the padlocks  10  and  110  are locked. 
     If a customer requires a lockout lock having a long housing  20  (for example having warning messages in multiple languages printed on the housing  20 ), it is possible to retroactively convert a standard size first padlock  110  according to  FIG. 3  to a so-called “long-body” type second padlock  10  by simply exchanging only the housings  120 ,  20  and shackles  114 ,  14 . Such a method of retrofitting a padlock includes the steps of: removing the housing  120  and the shackle  114  of the first padlock  110  from its lock body; and mounting instead the second shackle  14  and the second housing  20  to the lock body. 
     More particularly, the step of mounting the shackle  14  and the housing  20  to the lock body may generally comprise: inserting the second shank  34  of the shackle  14  into the second passage  30  of the lock body  12  (see  FIG. 1 ); retaining the second shank  34  in the second passage  30 ; and subsequently encasing the lock body  12  by means of the housing  20 . 
     For example, the second shank  34  is introduced into the lock body  12  of the padlock  10  via the second passage  30  until the second shank  34  of the shackle  14  abuts at an end of the second passage  30  (see  FIG. 1 ). Once the second shank  34  abuts the end of the second passage  30  the retaining pin  44  is introduced substantially perpendicular to the second shank  34  into a bore  45 , i.e. the shackle retaining pin  44  and the bore  45  are oriented in a transverse direction with respect to an axis of the second shank  34  of the shackle  14 . In this way the shackle  14  is retained in the second passage  30  and can only move in the direction A by the distance X. The retaining pin  44  is only introduced into the bore  45  in a loose manner, such that the retaining pin  44  can be removed again if necessary and the housing  20  and/or the shackle  14  can be exchanged without the need of a tool. During the assembly the housing  20  can already be positioned partly over the lock body  12  such that the bore  45  is still accessible and the second shank  34  can be introduced into the lock body  12 . Once the retaining pin  44  has been introduced into the lock body  12 , the housing  20  is slid further over the lock body  12  and the plastic bumper  22  is placed over the end of the housing  20  (for example forming a snap-fit) in order to secure the housing  20  to the padlock  10 .