Abstract: Wall members (1) of a partition wall which can be assembled by roller cross-heads (1a, 1b), along a main guide rail (3-3a) and branch rails (3b, 3c) of displaceable wall members (1) are displaced (A, B, C) by self-propelling trolleys (2, 2a, 2b) which move inside a continuous channel provided in or on the guide rails (3-3a, 3b, 3c). The self-propelling trolleys (2, 2, 2b) have an electrical linking device (4) which acts on suspension projections (6) or recesses provided on the roller cross-heads (1a, 1b). One of the roller cross-heads (1a, 1b) of the wall members is mounted to be displaceable horizontally (1i), to move the sealing ledges (1d, 1e) in and out (1f, 1v) by way of a system of levers, connecting rods, and springs (1t, 1p, 1l, 1n, 1r, 1o).