the weights that for example are not made from corrosion proof material although according to a particular embodiment such weights are preferably primed or painted abrasion which might expose the corroding material is nevertheless possible specifically at lug engagement points this is effectively prevented by the plastic a side from this the lugs and lug recesses can also be configured so that in the assembled state the underside of weights 9 i l is spaced away from the upper side of assembly retainer 10 d so that weights 9 i l rest on lugs 11 e l as an alternative to this foam strips could also be introduced between the underside of the weights and the upper side of the assembly retainer so that the weights are protected on all sides from mechanical abrasion and are also vibration damped transport casters 14 b c are conventional casters mounted to stand foot body by bolts 16 extending through caster base 15 recess 4 d has in the region of its support wall 19 a at least one threaded hole 20 a b that with a bolt not shown serves to immobilize column 3 a not shown in fig5 and 6 as a special feature the configuration shown in fig5 and 6 has a threaded in threaded rod 12 f that has on its end.