A stairlift comprises a rail which in use is attached to a stairway; a carriage which is mounted on the rail for movement along the rail; and a chair mounted on the carriage on which a user sits while completing his/her journey.
The rail should fit the contours of the stairway as closely as possible so as to protrude into the stairway to the least possible extent. However there is an increasing demand for rails to be configured from a selection of standard rail components, and to be easily disassembled for re-use after an existing installation is no longer required. This means that the components that form the rail must be capable of being securely fixed together for use; but equally capable of being disassembled without damage.
One example of stairlift rail is formed from sections of round tube joined end-to-end. Each section has a flange or tang extending from the surface of the tube, the tangs of all the rail sections combining and being adapted to provide a drive surface for a pinion on the output shaft of a motor/gearbox unit mounted within the carriage. It is important that, when the rail is assembled, the sections of rail remain in the correct relative rotational position so that tangs of juxtaposed rail sections remain in alignment. Correct alignment of the tangs not only ensures the structural integrity of the rail as a whole, but is also necessary to maintain ride quality.
In the past, juxtaposed rail sections of this type have typically been held together by a split tubular internal spigot that is expanded to frictionally engage the inner surfaces of the tube sections. However, over time and when subjected to cycles of torque applied as the carriage moves up and down the rail, these frictional joints can loosen.
It is an object of the present invention to provide a method and/or apparatus for forming a stairlift rail that will go at least some way to addressing the aforementioned drawbacks; or which will at least provide a novel and useful choice.