A drive beam (18.2) for a reciprocating floor includes a pair of elongate U-shaped channel members with longitudinally extending edges arranged and welded together edge to edge to define an elongate substantially rectangular in transverse cross-section tube member with opposed welded side walls (718) each with a lengthwise welding seam. A pair of elongate opposed reinforcing members (712) is fast with a respective associated welded side wall (718) and located inside the tube member.