Rotation restricted barrel lock

#This invention relates to barrel locks, specifically to means for preventing rotation of a barrel lock when opened by a key.

#Barrel locks are used to secure meter rings like the ones shown in U.S. Pat. No. 4,702,093 (DeWalch, 1987), as well as a variety of other locking hardware. In the present disclosure, the term “locking hardware” is used to refer to any device which is secured by a barrel lock. A barrel lock, as defined in the present disclosure, is commonly characterized as having a generally cylindrical case with a head portion, a smaller diameter shank portion, and a shoulder portion interposed between the head and shank portions. The shank portion includes retaining means, usually a pair of retractable steel balls, to prevent extraction of the lock from the meter ring or other locking hardware when the lock is locked. Usually barrel locks are removed from the locking hardware when they are unlocked. In many cases removal of the lock is required for opening the locking hardware.

#Many barrel locks, such as the one described in U.S. Pat. No. 4,289,000 (Nielsen, 1981), rely on axial movement of the key to actuate the lock. Although the operation of axially actuated locks is independent of lock rotation, these locks have a relatively small number of possible key codes, are often easy to pick, and require the use of a rather large and cumbersome key. To overcome these difficulties, barrel locks have been developed which are actuated by rotation of the key relative to the lock. In the present disclosure, this type of lock will be referred to as a “rotationally actuated barrel lock.”

#FIG. 1 shows a cutaway view of a barrel lock installed in a typical meter box.

#FIG. 2 shows an isometric view of the preferred embodiment spring clip and barrel lock.

#FIG. 3 shows an isometric view of the preferred embodiment lock having flats on the shank.

#FIG. 1 shows a meter box 100 of the type commonly used in the utility industry. The door 102 of the box 100 is hinged generally at 104 and includes a central hole 106 with a surrounding boss 108 which serves to retain the meter 110. The bracket 120 is welded to the floor 112 of the box and includes a flat portion 122 with a lock receiving aperture 124 therethrough. The door 102 is usually secured with a barrel lock 114, which is inserted into the threaded flange 140 until the locking balls extend beyond the aperture 124 in the bracket 120.

#Referring to FIGS. 2 through 4, the present embodiment includes a modified lock 130 with two opposing flats such as 132a on the shank 134, and a spring clip 150 which is retrofitted onto the bracket 120. The spring clip 50 includes two flat spring portions 152a and 152b, and a flat plate portion 154 with a lock receiving opening 156 therein. Adjacent to the lock receiving opening 156 are two protrusions 158a and 158b, which include bent portions 160a and 160b, as shown in FIGS. 4 and 5. Referring to FIGS. 5 and 6, when the spring clip 150 is installed onto the bracket 120, the bent portions 160a and 160b extend into the lock receiving aperture 124 in the bracket 120. The flat spring portions 152a and 152b serve to maintain pressure between the flat plate portion 154 of the spring clip and the bracket, so that the bent portions 160a and 160b are retained in the aperture 124 and serve to secure the spring clip to the bracket. The protrusions 158a and 158b are sized and positioned to engage the flats 132a and 132b, respectively, on the shank 134 of the lock 130, and prevent rotation of the lock. In other embodiments, the clip or the original bracket could be constructed with any internal shaped means designed to engage the flats or other suitable shaped means on the lock case.

#FIG. 7 shows an alternative embodiment barrel lock 170 having a notch 172 in the shoulder portion 174. FIG. 8 shows a split bushing 176, with a prong 178 designed to engage the notch 172 in the barrel lock 170. Referring to FIG. 9, the bushing 176 is pressed or otherwise non-rotatably installed in the lock receiving portion 192 of the locking hardware 190 prior to insertion of the lock 170. When the lock is inserted, the notch 172 engages the prong 178, and the lock is prevented from rotating. FIG. 10 shows a split bushing 180 having a central aperture 182 with internal flats 184a and 184b, which are designed to engage the flats 132a and 132b on the barrel lock 130 shown in FIG. 3. In other embodiments, any suitable shaped means could be used to non-rotatably couple the bushing and the barrel lock.