rotated about a vertical axis between the fiber bale rows 2 and 3 without touching the side faces 2c or 3c thereof turning now to fig6 for determining the position of the carriage 5 there is used a counter 10 which is connected with a control device 11 such as a microcomputer including a microprocessor to the control device 11 there is connected with the intermediary of an interface 12 the driving device drive motor 13 for propelling the carriage 5 and the driving device drive motor 14 of the gearing not illustrated for turning the tower 4 the counter 10 is driven by the drive motor 13 by means of for example a mechanical coupling symbolically illustrated by a broken line to the control device 11 there is further coupled by means of an interface 15 a counter 17 which is driven by the drive motor 16 by means of for example a mechanical clutch the drive motor 16 effects the height adjustment of the opening device 7 the counting system informs the control device 11 of the exact position of the carriage 5 at each point in time in the control device 11 there are stored the geometrical initial positions a1 and a2 and the end positions e1 and e2 of the two bale rows 2 and 3 if for example as shown in fig3 a the end zone e2 is reached the control device computes how far the carriage 5 should travel in the direction of the location a2 to ensure that the opening device 7 may be turned without projecting beyond the end faces 2a 3a of the respective fiber bale rows.