Unattended trailer hitch lock

Abstract

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.