Shock absorber structure of a castor wheel

A shock absorber of a caster wheel comprising:

• a tubular leg, a mounting tube, a protective hood, a shaft, a top compression spring and a bottom compression spring, a caster seat, and a caster wheel;
• said tubular leg having three protruding stripes within an internal wall thereof, said internal wall being divided into three fan-like insertion slots, a bolt hole being formed on each protruding stripe;
• said mounting tube having an external peripheral edge configured with three fan-like filing blocks adapted to be inserted into said fan-like insertion slots of said leg, a top end of said mounting tube having a cap attached thereto and a bottom end being screwed with a circular base seat, the center of said cap provided with a circular hole and the base seat provided with a hexagonal hole, said base seat having three securing holes corresponding to the bolt holes of said protruding stripes;
• said protective hood having an inner surface and provided therein a horizontal partition board having a hexagonal through hole in communication with the Interior of the mounting tube, said partition board further having three mounting holes corresponding to the bolt holes and the securing holes;
• said shaft having a hexagonal middle portion, a circular top end portion, and a circular bottom end portion, free ends of said top and bottom portions being threaded;
• said caster seat having said caster wheel mounted to a lower portion thereof, an upper portion having a bearing seat with an insertion hole receiving two bearings, and
• wherein said tubular leg, said mounting tube and said protective hood are mounted together by screws through said bolt holes, securing holes and mounting holes;
• said shaft extends through said hexagonal hole of said protective hood and said hexagonal hole of said base seat;
• said top end portion of the shaft protrudes through the circular hole of said cap and said bottom end of the shaft portion protrudes through the insertion hole of the bearing seat and the bearings;
• a nut is mounted on the threaded end of the bottom end;
• said top compression spring is mounted on the top end portion of the shaft between the cap and the middle portion, and the bottom compression spring is mounted on a bottom portion of the middle portion of the shaft between the bearing and the protective hood.