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STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
   Not applicable. 
   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to cable locks, and particularly to cable locks used in secure facilities where there is a risk of residents utilizing heavy, portable objects as weapons. 
   2. Description of the Prior Art 
   Secure institutions such as prisons, schools, and hospitals often have means for residents to store personal property, such as lockers, storage cabinets, or foot lockers. These storage facilities are typically secured by using a padlock of some sort, operable either by key or combination. The locks most commonly employed at present are constructed primarily from hardened steel, which increases the weight of the padlocks, and results in a rigid structure. One popular model weighs close to six ounces despite being less than three inches in length. This poses a security problem itself: the relatively heavy weight and rigid structure of the locks allows them to be effectively used as weapons by residents, either as a projectile or by placing the lock inside a sock to form a makeshift bludgeon. 
   A cable lock, with its flexible cable, greatly reduces the rigid structure of a traditional padlock and thus reduces the potential for injury if the lock is used as a projectile. Combination-operated cable locks are known in the prior art, being typically utilized to temporarily secure bicycles and other moveable objects to a stationary object. However, such locks typically have cables or chains several feet in length and of at least ¼″ in diameter to accommodate a variety of objects being secured, and to enable such objects to be secured to stationary objects of varying size and shape. The length and diameter of these cables renders them heavy and typically impractical or unusable for securing lockers and other containers in institutional settings such as prisons, schools, and hospitals. 
   Alternatively, lightweight cable locks having a rigid plastic body are known in the prior art, and are typically used by travelers to secure luggage. Such locks may have a significant length of retractable cable, which poses its own danger in an institutional setting as a weapon. Furthermore, the plastic bodies of these locks are not usually impact or tamper resistant, which diminishes their security. 
   U.S. Pat. No. 5,819,560 illustrates a padlock possessing a composite plastic body, which reduces weight. However, the padlock still possesses a rigid structure by virtue of its hardened steel and dense plastic structure, which increases the risk of injury if the lock is thrown. It also is key-operated, which present the added problem of keys that secured residents have to keep, with the risks of loss or theft. 
   BRIEF SUMMARY OF THE INVENTION 
   The present invention summarized is a locking device consisting of a flexible cable of small diameter and short length, attached at one end to a locking mechanism of a combination or permutation type capable of being engineered smaller and lighter than the combination locking mechanisms typically found in prior art cable bicycle locks. The other cable end is attached to a key designed to be received and secured into the locking mechanism. The key and locking mechanism are fabricated from a lightweight material, such as aluminum or titanium, and preferably in a relatively simple mechanical fashion to ensure light weight, while retaining strength, security, and reliability. The cable is made of a flexible material of high tensile strength that is cut-resistant, such as braided or twisted steel strands, as is well known in the art, and may be coated with a durable plastic sheath such as vinyl or PVC to further protect the cable. Additionally, the locking mechanism is designed to accept a master key, which enables the administrator of an institution that the locking device is ideally suited for to unlock any lock on the premises without needing to know each individual lock&#39;s unique combination. 
   In the preferred embodiment, the locking mechanism consists of a hollow cylinder surrounded by a series of numbered, notched dials. The key has arranged along its length a series of locking lugs corresponding to each of the numbered dials. To close and secure the lock the numbered dials are aligned to a preset combination, the key is inserted into the hollow cylinder, and is finally secured into the body of the lock when the numbered dials are aligned to any combination other than the preset. 
   It is an object of the invention to provide a reasonably strong and secure padlock for use primarily by patients, residents, or incarcerated inmates in an institutional setting which will allow residents to secure their property. It is a further object of the invention to provide a padlock that is small enough and light enough so that it is not practically useful as a weapon. 

   
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
       FIG. 1A  is a perspective view of a lock as constructed according to the present invention; 
       FIG. 1B  is a sectional view of the lock as shown in  FIG. 1A ; 
       FIG. 1C  is an exploded view of the lock as shown in  FIG. 1A ; 
       FIGS. 2A-E  are component views of the notched numerical dials as shown in  FIG. 1  that form part of the locking mechanism of the preferred embodiment; 
       FIGS. 3A-C  are component views of the lock core as shown in  FIG. 1  that forms part of the locking mechanism of the preferred embodiment; 
       FIGS. 4A-D  are component views of the key as shown in  FIG. 1  that forms part of the locking mechanism of the preferred embodiment; 
       FIGS. 5A-C  are component views of the tabbed washers as shown in  FIG. 1  that form part of the locking mechanism of the preferred embodiment; 
       FIGS. 6A-C  are component and sectional views of the assembled lock core end housing as shown in  FIG. 1  and lock core as shown in  FIG. 3  that form part of the locking mechanism of the preferred embodiment; 
       FIGS. 7A  and B are component views of the cammed locking washers disposed inside of the lock core end housing shown in  FIG. 6  that form part of the locking mechanism of the preferred embodiment; 
       FIGS. 8A  and B are component views of the swaged key fixably attached to the end of the cable as shown in  FIG. 1  that forms a part of the locking mechanism of the preferred embodiment; 
       FIGS. 9A-D  are component views of a lock core end housing half as shown in  FIGS. 1 and 6  that form part of the locking mechanism of the preferred embodiment; 
       FIGS. 10A-C  are component views of the numerical index ring as shown in  FIG. 1  that forms a part of the locking mechanism of the preferred embodiment; and 
       FIGS. 11A-C  are component views of the cammed key used to effect removal of the swaged key as shown in  FIG. 8  from the lock core end housing as shown in  FIG. 6 , useful with the locking mechanism of the preferred embodiment. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   Referring to the figures, the preferred embodiment is showed in  FIGS. 1A-C . The lock consists of a cable  6 , which is permanently attached at one end to a key  1 . The other end of the cable  6  is attached to a lock core housing  2 , which in turn holds a hollow core shaft  20  in place. A lock assembly  3 , formed from a plurality of numerical dials  30  interleaved with an equal number of tabbed washers  50 , is fitted onto the shaft  20 . The lock assembly  3  is held in place on the shaft  20  by affixing a retaining clip  4  onto the end of the shaft  20  distal from the core housing  2 . The cable  6  is attached to the key  1  by fastening means that are well known in the art. The cable  6  is attached to the core housing  2  by inserting a swage key  80 , which is permanently affixed to the end of the cable  6 , into the end of the core housing  2  where a securing mechanism housed therein locks the cable  6  into place. The cable  6  may be removed by inserting the master unlock key  7  into the end of the core housing  2 , thereby disengaging the securing mechanism and releasing the cable  6 . An alternative embodiment has the securing mechanism embedded into the end of key  1 , where the key is comprised of a separate key shaft secured into a key housing, and core housing  2  and shaft  20  comprising a single, unified, cast piece. 
     FIGS. 2A-D  depict the numerical dials  30  which form a part of the lock assembly  3 . Each dial  30  is disc-shaped, possessing a first surface  37 , a second surface  38 , a third essentially circular surface  35  running perpendicular to the first surface  37  and the second surface  38  and defining the outermost circumference of the dial  30 , and a circular flange  36  normal to and extending from the second surface  38 , concentrically inset from the circular surface  35 . A center hole  31  is positioned concentrically in and runs perpendicular to the first surface  37  and the second surface  38 . A notch  32  radially extends from the center hole  31  and is sized to an identical width as channel  22  and a height sufficient to just accommodate locking lugs  12   a ,  12   b ,  12   c , and  12   d . The center hole  31  is sized so as to allow the dial  30  to slide onto the shaft  20  and spin freely in place, but with minimal play. The circular flange  36  should extend from the second surface  38  a distance at least equal to the length of one of the corresponding locking lugs  12   a ,  12   b ,  12   c , or  12   d , less the thickness of a tabbed washer  50 . Disposed and equally spaced upon circular surface  35  are a plurality of numbered concave depressions  34  equal to and corresponding with the number of stops on the numbered dial  30 . A unique symbol, number, or other identifying mark is affixed to each concave depression  34  to facilitate entry of the lock&#39;s preset combination. A series of small round depressions  33 , located on the first surface  37 , equal in number to the number of stops on the numbered dial  30 , and equally spaced around and radially positioned adjacent to the center hole  31 , engage a protrusion  54  on each interleaved tabbed washer  50 , thereby providing a positive stop for each depression  34 . 
   The lock core of the preferred embodiment is built upon a core shaft  20 , depicted in  FIGS. 3A-C . The core shaft  20  is tubular in shape, possessing a center bore  21  and at least one radially disposed channel  22  that runs the length of the core shaft  20 . Core shaft  20  is of a length sufficient to accommodate the complete lock assembly  3  and ensure it is held fast with a minimal amount of play along the length of shaft  20  when the shaft  20  is secured into the core housing  2  and retaining clip  4  is affixed. The center bore  21  is sized and shaped to just accommodate key shaft  11  with a minimal of play, while the channel  22  is sized to accommodate the protruding locking lugs  12   a ,  12   b ,  12   c , and  12   d . Also radially positioned around the circumference of core shaft  20  are a plurality of notches  23   a ,  23   b , and  23   c  positioned so as to engage an equal number of protrusions  53  on each tabbed washer. The core shaft  20  is attached to the core housing  2  by fitting the two halves of the core housing  2  around notch  26  and flange  27  on shaft  20 . The lock assembly  3  of interleaved numerical dials  30  and tabbed washers  50  are secured in place on the core shaft  20  by use of retaining clip  4 , which is positioned in groove  24 . Ideally the core shaft  20  as depicted in  FIGS. 3A-C  is fabricated as a single piece of cast aluminum, to ensure simplicity, light weight, and low cost. 
   In  FIGS. 4A-D  the key  1  consists of a key shaft  11  of a diameter sized to fit within the center bore  21  of the core shaft  20 . Radially disposed along the length of the key shaft  11  are locking lugs  12   a ,  12   b ,  12   c , and  12   d , separated from each other by spaces  13   a ,  13   b ,  13   c , and  13   d . The lugs  12   a ,  12   b ,  12   c , and  12   d  are radially positioned and each sized so as to engage channel  22  of the core shaft  20  and when fully inserted into the lock assembly  3  fit within the space between the numerical dials  30  created by each flange  36 . The spaces  13   a ,  13   b ,  13   c , and  13   d  are each sized so as to accommodate the thickness of a numerical dial  30  as measured between the first surface  37  and the second surface  38 . Key  1  may be permanently attached to the end of cable  6  by crimping a barbed fitting onto the end of cable  6  and inserting the end into cavity  14 , where the barbed fitting can engage channel  15 ; however, any method which allows for the permanent and secure attachment of key  1  onto the end of cable  6  is appropriate and in keeping with the scope of the invention. Should a different attachment method be utilized, cavity  14  and channel  15  may be modified or omitted, as appropriate. Ideally the key  1  as depicted in  FIGS. 4A-D  is fabricated as a single piece of cast aluminum, to ensure simplicity, light weight, and low cost. 
     FIGS. 5A-C  depict the tabbed washers  50 . Each washer  50  is roughly disc-shaped, possessing a first surface  51  in a second surface  52 . A center hole  55  is concentrically centered and runs perpendicular between the first surface  51  and the second surface  52 . A notch  56  radially extends from the center hole  55  and is sized to an identical width as channel  22  and a height sufficient to just accommodate locking lugs  12   a ,  12   b ,  12   c , and  12   d . The center hole  55  is sized so as to allow the washer  50  to slide onto the core shaft  20  with minimal play. A plurality of protrusions  53  are radially disposed around the circumference of the center hole  55  and placed so as to engage notches  23   a ,  23   b , and  23   c  on the core shaft  20 , thereby fixably placing notch  56  in line with the channel  22  and preventing the washer  50  from rotating around the core shaft  20 . A second protrusion  54  engages depressions  33  on numerical dial  30  so as to provide positive detents for each numbered depression  34  on numerical dial  30 . Tabbed washer  50  is ideally machined from steel for enhanced durability. 
   The cable  6  is secured to the lock core housing  2  through a securing mechanism contained in the end of the lock core housing as depicted in  FIGS. 6 through 9 . Turning to the figures which show the preferred embodiment of the securing mechanism as assembled into the core housing  2  and its working components, swage key  80 , permanently affixed to one of the ends of cable  6 , is inserted into aperture  91 , where it makes contact with locking disc  70 . Increasing pressure on the swage key  80  results in the locking disc  70  rotating to accommodate the swage key flat  83 . Once the swage key flat  83  passes the locking disc  70 , circular spring  61  forces the locking disc  70  to rotate back around the swage key  80  through the swage key locking channel  82 , thereby securing the cable  6  to the core housing  2 . Turning to  FIG. 8 , the swage key  80  is permanently affixed to the cable  6  by inserting an end of the cable  6  into the swage key end cavity  84 , then crimping the swage key barrel  81  onto the cable  6 . 
   Details of the locking disc  70  are depicted in  FIG. 7 . The locking disc  70  is roughly disc-shaped, possessing a first surface  71  and a second surface  72 . A center hole  76  is concentrically centered and runs perpendicular between the first surface  71  and the second surface  72 . The circular spring  61  engages hole  73  to allow the spring  61  to rotate the disc  70  into a locked position. The disc  70  secures the swage key  80  in place by use of a flat  74  that corresponds to swage key flat  83 . As the swage key flat  83  passes the disc flat  74 , the circular spring  61  rotates the disc flat  74  out of alignment with swage key flat  83 , and into swage key locking channel  82 . A cam lug  75  extending radially from the outer circumference of the disc  70  engages the master unlock key  7 , which thereby forces the disc  70  to rotate against the tension of circular spring  61 , bringing flat  74  back into alignment with swage key flat  83 , and thereby allowing removal of the swage key  80  from the core housing  2 . 
   The core housing  2  is depicted in greater detail in  FIG. 9 , and is assembled from two mirrored halves. The swage key  80  is inserted into aperture  91 , which is shaped so as to accommodate the cross-sectional profile of the swage key  80  as taken from the portion of the key possessing the flat  83 , thereby preventing the swage key  80  from rotating within the aperture  91 . Alternatively, recession  96 , located at the bottom of aperture  91 , may be shaped so as to receive the tip of swage key  80  so modified in shape as to prevent the swage key  80  from rotating within the aperture  91 . The locking disc  70  is placed into channel  95 , with the circular spring  61  located immediately beneath it, as viewed in  FIGS. 9A and 9C . One end of the circular spring  61  engages notch  62 , to allow the spring  61  to be tensioned. An arc-shaped slot  94  is provided to insert the master unlock key  7 , allowing access to the locking disc  70 . End flange  27  and groove  26  on core shaft  20  fit into notch  93 , to fixably secure shaft  20  to end housing  2 . Once the shaft  20  and components of the mechanism to secure cable  6  are placed into one of the halves of end housing  2 , the two halves are mated and permanently secured together by use of two drift pins placed into holes  92   a  and  92   b.    
   An index ring  100 , depicted in  FIG. 10 , is slipped over the core shaft  20  to provide a fixed index mark  101  which serves as a reference for dialing the lock&#39;s unique combination into the numerical dials  30 . The index ring  100  is fixed in place and prevented from spinning around the core shaft  20  by the presence of a notch  102 , which is sized to just engage an index tab  25  with minimal play, located on the end of the core shaft  20  proximal to the core housing  2 . 
   The master unlock key  7 , depicted in  FIG. 11 , is fabricated from a single curved piece of metal, and is sized so as to just fit inside slot  94  on core housing  2 . Into one end of the unlock key  7  a curve  111  is milled, and set partially into the inside curve of the key. This curve  111  engages cam lug  75  as described above, allowing for the quick opening of the lock. 
   To close the lock, the numerical dials  30  are turned to the lock&#39;s preset combination by lining up the appropriate numbered depressions  34  with index mark  101 , which causes notches  32  to line up with channel  22 . The key  1  is then inserted into the lock core shaft  20 , where locking lugs  12   a ,  12   b ,  12   c , and  12   d  fit into the spaces created by flanges  36 . The numerical dials  30  are then turned to a combination other then the lock&#39;s preset combination, thereby securing the key  1  into the core shaft  20  as each notch  32  is rotated out of alignment with channel  22 . The lock may be opened by resetting the numerical dials  30  to the lock&#39;s preset combination, and then pulling the key  1  from the core shaft  20 . 
   The above embodiment is only used to illustrate one possible method of practicing the present invention, and is not intended to limit the scope thereof. A person having skill in the art will recognize changes that may be made thereto while still practicing the claimed invention.

Summary:
A cable padlock having a thin flexible cable, with a key attached to one cable end and a locking mechanism for receiving and securing the key attached to the other cable end, preferably of a combination or permutation type. The key and locking mechanism are constructed of lightweight materials such as aluminum, providing for a lightweight, compact, and potentially inexpensive padlock. A mechanism for detaching the cable from the locking mechanism by application of a master key is provided to allow an administrator of a facility utilizing a number of the locks to remove each lock without needing to lookup each lock&#39;s unique combination. The lock is accordingly useful in prisons, institutions, and other secured facilities where there are concerns that a traditional heavier lock could be used as a makeshift weapon.