Rear hub transmission mechanism for bicycles

An improved rear hub transmission mechanism for use in bicycles, said mechanism comprising a hub body having a central through hole for insertion of an axle, one end thereof being provided with a ball bearing slot for receiving, in sequence, a ball race, a ball nest and an axial sleeve;

• a sleeve inserted into said through hole of said hub body via one end of said through hole, said sleeve being positioned within said hub body by means of a nut screwably provided on said axle;
• and a driving assembly consisting of a mounting, a pre-determined number of retaining elements and a gear seat, said mounting having a pre-determined number of notches circumferentially provided therein for acccommodating said retaining elements, said retaining elements being pressed against by a resilient member, one end of said mounting being provided with a tube which passes through said axle into a round hole at one end of said through hole of said hub body, an inner surface of said gear seat being provided with internal ratchet for meshing with said retaining elements of said mounting, one end of said gear seat being fitted with a ball bearing set and a protective cover so that by means of a socket, a jacket and a nut, all components are pressed tightly onto said hub body, an outer surface of said gear seat being provided with a driving gear for driving said hub body unidirectionally, wherein
• an inner surface of said through hole of said hub body is circumferentially axially provided with a plurality of elongated grooves and one end of said through has a polygonal hole;
• said sleeve has a lower section of a smaller diameter and which is provided with external threads and a bracing section above said external threads, and an upper section of a greater diameter which forms a sleeve body having a plurality of elongated grooves circumferentially and axially disposed therein, said upper section of said sleeve having a polygonal flange at one end thereof for matching with said polygonal hole at one end of said through hole of said hub body, said polygonal flange having a polygonal orifice in the center thereof, said elongated grooves of said upper section of said sleeve locking with said elongated grooves in the inner surface of said through hole when said sleeve is inserted into said through hole of said hub body, with said polygonal flange of said upper section of said sleeve fitting in with said polygonal hole of said through hole;
• said tube at one end of said mounting is provided with internal threads and a smooth bracing surface above said internal threads, said external threads of said lower section of said sleeve inserted into said through hole engaging with said internal threads of said tube of said mounting when said tube is passed through said axle into one end of said through hole of said hub body, and said bracing section of said lower section of said sleeve pressing tightly against said bracing surface of said tube of said mounting to prevent said sleeve from moving forward.