Telescopic ladder

A telescopic ladder comprising a telescopic ladder section and a ladder foot section, wherein the telescopic ladder section comprises a rail that is configured to have a fit between at least two rungs:

• each rung of rail includes a rung, a bracket, and a rail tube, wherein the bracket has a plug-in channel that runs through the top and bottom, a connector is provided on the side of the bracket, the inner wall of the plug-in channel is spaced with at least four fitting bumps, and a upper port of the plug-in channel is provided with an inward flanging that extends towards the center direction of the plug-in channel;
• the upper end of each rail tube is inserted into the corresponding bracket's plug-in channel through the lower port of plug-in channel and pressed against the inward flanging to connect the rail tube and the bracket, the fitting bumps reduce the fitting gap between the rail tube and the plug-in channel of bracket, and a descent control device is provided at a lower port of each rail tube;
• the rungs are disposed between the rail tubes, and the ends of the rungs are connected to the corresponding connector, respectively;
• a rail tube of an upper rung of rail is disposed inside a rail tube of a lower rung of the rail, and a folding mechanism is provided between the upper rung of rail and lower rung of rail to lock or unlock the unfolded state between the upper rung of rail and the lower rung of rail;
• the ladder foot section comprises a rung, a bracket, and a ladder foot tube, wherein the bracket is provided at the ladder foot tube, and the rung is disposed between the rail tubes, the ends of the rung are connected to the corresponding connectors, respectively;
• the rail tube of the last rail is sleeved inside the ladder foot tube of the ladder foot section;
• the rail tube of the upper rung of rail has a smaller size than the rail tube of the lower rung of rail, and the rail tube of the last rail has a smaller size than the ladder foot tube;
• the rail tube comprises a first arc edge plate, a straight edge plate, and a second arc edge plate, wherein one end of the straight edge plate is connected to the first arc edge plate, and the other end of the straight edge plate is connected to the second arc edge plate, a first circular arc angle is formed at the connection between the straight edge plate and the first arc edge plate, and a second circular arc angle is formed at the connection between the straight edge plate and the second arc edge plate, thereby enclosing a rail tube having a “bread” shaped cross section;
• an inner wall of an opening of the bracket is spaced with at least four fitting bumps that are configured to enclose a limit port, the upper rung of rail tube passing through the limit port of the bracket is sleeved inside the rail tube of the lower rung of rail, and the limit port is configured to reduce a fitting gap between the upper rung of rail tube and the bracket;
• the rung has a curved surface that is easy to step on, and the size of the rung of the telescopic ladder is configured to increase with the size of the rail tube.