A system intended for the transport and storage of product carriers, comprising a plurality of elongated transport units, adapted to be connected to each other so as to form a transport network. The transport units comprise a frame (1a, 1b; 2a, 2b etc.) with carrier rollers (7) for the product carrier (9) and an elongated transporting screw (15) provided with driving members (17), the threads of which are adapted to cooperate with engagement members (43) provided at the bottom side of the product carrier in such a manner that upon operation of the screw (15) the product carrier (9) is advanced along the transport unit, the transporting screws (15) being driven in such a manner that they are always started and stopped in a predetermined position of the transporting screw. By means of a computer apparatus counting and registering the number of revolutions of the transporting screws a permanent and exact control of the position of each product carrier in the system is made possible. The engagement members (43) of the product carriers (9) may be formed by ridges, spaced mutually along the transporting screw with the same cross-sectional thread profile as the thread groove of the transporting screws, said rims each meshing with the transporting screw during the transport.