A plurality of first moulding holders (16), each for a first moulding (22), is arranged in peripherally staggered array to pivot about a tangential axis (B) on a turntable (10) which can be stepwise rotated about a central pivot (A). A corresponding number of second moulding holders (18) for a second moulding (24) each, which can be moved towards and away from an appropriate first moulding holder (16) in order to bring together or separate the appropriate mouldings (22, 24), is arranged on the turntable (10). Beside the turntable (10) there is an unmoulding station (30) with a pivoting drive (90) to pivot a pair of moulding holders (16, 18) to and fro between a casting and an unmoulding position. Tensioners (42, 44) are arranged to pivot about the axis (B) on the moulding holders (16, 18) with the latter and can be locked and unlocked together in pairs by remote actuation. Drives (60, 70, 80) for actuating the tensioners (42, 44) and to move a pair away and towards each other into the unmoulding position of pivoted moulding holders (16, 18) are arranged solely in the unmoulding station (30).