Steering wheel lock

A steering wheel lock comprising a casing having a front side and a rear side and a lock cylinder at the rear side, a stop bar having a coupling rod at one end fastened to the front side of said casing and adapted for stopping at an instrument board of a motor vehicle, a clamping plate coupled to the casing and locked by said lock cylinder to secure said casing to a steering wheel, a partition plate mounted inside said casing, and an alarm circuit assembly mounted on said partition plate inside said casing, wherein:

• said casing comprises two wheel-like circular coupling blocks bilaterally disposed at the rear side and spaced from each other by a space, two arched wing plates disposed at two opposite lateral sides and adapted for covering over the periphery of the steering wheel, and a mounting hole at the front side, which receives the coupling rod of said stop bar, said arched wing plates each having a sloping flange at an outer end for fitting over the periphery of the steering wheel;
• said partition plate comprises a top platform which holds said alarm circuit assembly, a flat front extension board and two rear tabs respectively fastened to said casing on the inside by respective screws, and a speaker mounting hole at said front extension board;
• said alarm circuit assembly comprises a battery box fastened to the platform of said partition plate, a battery mounted in said battery box, an alarm control circuit fastened to said battery box at one side and having a switch lever inserted through said partition plate and adapted for pressing on the steering wheel to alert said alarm circuit assembly, and a speaker mounted in said speaker mounting hole and connected to said alarm control circuit by an electric wire;
• said clamping plate comprises an elongated, smoothly curved clamping section adapted for covering over the periphery of the steering wheel at the bottom, a flat rib raised from one side of said clamping section in the middle, and a circular coupling block connected to said flat rib and inserted into the space of said casing and pivotably connected between the two circular coupling blocks of said casing by a pivot, the circular coupling block of said clamping plate having a plurality of transverse teeth raised around the periphery for the engagement of a lock bolt of said lock cylinder, the clamping section of said clamping plate having two sloping flanges at two opposite ends for fitting over the periphery of the steering wheel.