UNATTENDED TRAILER HITCH LOCK
A trailer hitch lock provides a finned, external shell around a centrally-disposed lock assembly. The material of the shell, its distribution of fins, and the fin dimensions all cooperate to defeat a destructive attack on the lock by a portable angle grinder.
1 . A trailer hitch lock that comprises: (a) a lock assembly that includes a locking mechanism operably movable vertically from a first unlocked position into a second locked position, wherein said locking assembly is disposed in a vertically-oriented, central chamber located within (b) a shell comprising a plurality of fins that radially extend from said locking assembly by a distance within the range of 36-100 mm, wherein the shell surrounds said lock assembly and engages a trailer hitch receiver coupling.
2 . A lock according to claim 1 further comprising one or more seals around movable parts to provide resistance to moisture infiltration into said lock.
3 . A lock according to claim 1 wherein said lock assembly further comprises a freely rotating ring around a key opening into a locking mechanism, said ring having a central hole that tapers at an angle within the range of 75°-100° towards an opening that exposes said key opening.
4 . A lock according to claim 1 wherein the shell is made from aluminum alloys having a Knoop hardness of at least 50.
5 . A lock according to claim 4 wherein the shell is made from aluminum alloys having a Knoop hardness within the range of 70-140.
6 . A lock according to claim 1 wherein said lock assembly is made of stainless steel.
7 . A lock according to claim 1 wherein said lock assembly in secured in said shell with a locking ring having radially extending, diametrically opposing, threaded, openings that receive set screws from within said locking ring and extending radially outwardly in said openings into a recess of said shell.
8 . A lock according to claim 1 wherein said shell has a plurality of fins that radially extend from said locking assembly by a distance within the range of 40-75 mm.
9 . A lock according to claim 1 wherein the fins are distributed around the shell surface at a radial fin-to-fin distribution angle that is within the range of 30-40°.
10 . A lock according to claim 1 wherein said shell is a unitary part that has been cast in place around said lock assembly.
11 . A lock according to claim 1 wherein said shell is made of a hardened steel core coupler sandwiched between a top shell piece and a bottom shell piece that are joined together around the core coupler.
12 . A lock according to claim 1 wherein the lock assembly further comprises a locking ring that is secured in position in said shell with a pair of opposing set screws that can only be accessed when the lock assembly is in an unlocked position and removed, wherein the set screws extend into a groove in said shell.
13 . A trailer hitch lock that comprises: (a) a lock assembly that includes a locking mechanism operably movable vertically from a first unlocked position into a second locked position, wherein said locking assembly is disposed in a vertically-oriented, central chamber located within (b) a shell comprising a plurality of fins that radially extend from said locking assembly by a distance, wherein the shell surrounds said lock assembly and is shaped to receive and engage a trailer hitch receiver coupling.