Abstract: The lifting and rotating zeroes and the combination discs of a disc cylinder lock are provided with curved internal camming surfaces designed to mate with external curved camming surfaces on the key shank. The curved camming surfaces consist of segments of mathematically defined spirals, with non-uniform radii as measured from the lock axis.

Abstract: A lock assembly for preventing unauthorized opening of a utility meter box cover. The assembly includes a lock housing detachably mounted to a box side wall by a fastener which is accessible from the box interior. A post is shiftable in a passageway extending through the lock housing between an operative position overlapping the cover and a retracted position clear of the cover. A barrel lock is removably received in the lock housing to prevent shifting of the post from its operative to its inoperative position.

Abstract: A split retaining ring is disclosed for detachably interconnecting a pair of axially aligned circular rims. The ring has ends and a circular side wall with front and rear flanges protruding radially inwardly therefrom. The ring ends are resiliently separable to accommodate installation and removal of the ring onto and off of the rims, and are resiliently closeable to confine the rims radially within the ring side wall and axially between its flanges. The rear flange has a radially tapered configuraiton with oppositely disposed minimum radial dimensions arranged to minimize the extent of separation required between the ring ends during installation and removal.