A central-controlled double wheel structure, which comprises:
- an upper base, wherein one side of the upper base comprises a partitioning board which separates a space into two opposing assembling compartments located at both sides of the partitioning board, the partitioning board has a central hole that connects these two opposing assembling compartments, each of the two opposing assembling compartments is installed with a braking pad, with one end of the braking pad extending outwards to form a serrated cogging end, and the other end having a coupling hole, the other side of the upper base has an uprightly placed slot and a through hole which is laterally opened at the wall and connects the two opposing assembling compartments to the slot;
- a lower base, wherein the lower case is assembled to the bottom portion of the upper base, and comprises two connecting boards, each of the two connecting boards is interposed into an assembling compartments of the upper base and has an axial through hole corresponding to the position of the central hole of the central partitioning board, the axial through holes of the two connecting boards and the central hole of the central partitioning board are connected with a central rod, two wheel bodies are assembled to the outer ends of the central rod at the outside of the connecting boards, and each wheel body has a set of cogging teeth located at the inner wall corresponding to the position of the serrated cogging end of the braking pad of the upper base;
- a braking component, wherein the braking component comprises a braking block, a direction limiting member, a toothed braking member, and a connecting seat, which are interposed into the slot of the upper base following the order as above mentioned, the braking block has a head portion with the top end of the head portion being formed into a non-circular assembling hole, two recessed position restricting portions and two toothed cogging portions located at the bottom edge of the head portion, a cone-shaped pole member extending downwards from the center region of the bottom side of the head portion, and the bottom side of the cone-shaped pole member is connected to a holding member which is fitted into a first spring, the direction limiting member has a through hole located in its center which allows the cone-shaped pole member to pass through, two direction positioning convex portions located at two sides of the direction limiting member, and these direction positioning convex portions each has a bulged position limiting portion located at their upper surfaces, the toothed braking member has a through hole in its center that allows the cone-shaped pole member to pass through, two recessed slots located at two sides of the toothed braking member and these recessed slots allow the interposition of the two convex direction positioning portions of the direction limiting member, and toothed portions located at an inner wall of the toothed braking member corresponding to the positions of the toothed cogging portions of the braking block, the connecting seat resides onto a supporting portion of the lower base with its bottom portion which is fitted into a fourth spring, has a top surface that allows the second spring and the third spring to reside against and a convex supporting portion located at the center of the top surface, and also has two connecting plates that are located at one side of the connecting seat and are extended into the two opposing assembling compartments of the upper case from the through hole with each connecting plate being connected with one of the braking pads by a bridge plate;
- a control component, wherein the control component comprises a post member, the lower end of the post member is interposed into the slot of the upper case facilitated with two bearings, and the top end of the post member has a recessed ring slot and a through hole across the top end with threaded openings, the post member has a central axial hole along its length and receives an axial rod, the bottom end of the axial rod is formed into a non-circular structure which allows it to be interposed into the assembling hole of the braking block, the top end of the post member is fitted into an elastic member and is fixedly connected with a connecting member, the connecting member is mounted with a connecting block which has on its top side a recessed slot, and the recessed slot receives a portion of a round pillar member with a certain portion of the pillar member remains outside of the recessed slot;
- an aluminum control rod, wherein the aluminum control rod comprises two housing members which are assembled opposing to each other, and encloses the control component into the space formed with the two housing members, the top end of the aluminum control rod has a laterally placed through hole, and a chamber formed inside of the aluminum control rod which has a bulged position limiting stopper point located at its top side and is installed with an adjusting member, the adjusting member has a non-circular opening that opens towards the through hole of the aluminum control rod, a recessed cogging portion and a direction-limiting slot that are located at the bottom end of the adjusting member, and convex braking portions that are located at opposite sides of the adjusting member.