The present invention relates to a Radial Expand Collapse or REC tyre building drum of adjustable width for use in the manufacture of tyres of different widths employing the same tyre building drum. REC tyre building drums are broadly of two distinct kinds; those in which rotary movement of a central shaft collapses the drum and those in which a push/pull movement of the central shaft collapses the drum. A rotary REC tyre building drum is disclosed comprising a plurality of segments (14,16) defining an outer circumference of the tyre building drum, the segments being divided into two sets (6,8), one set being located to each opposite side of a transverse central plane (10) of the tyre building drum, the central plane being disposed normal to the rotational axis (12) of the drum, the two sets of segments being adapted to be driven by a rotatable hub assembly between a collapsed position and an expanded position wherein the tyre building drum further comprises mounting each set of segments for selective relative axial positioning to each opposite side of the transverse central plane and means located outside of the rotational axis of the drum to adjust the overall working width of the drum. It is an advantage of the present invention that it allows for an axial positioning mechanism for a rotary REC tyre building drum.
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