rising by rotating anticlockwise in the direction of the arrow b whereas a decrease in the sliver tension results in the bar 11 lowering by rotating clockwise in the direction of the arrow c the sensor 16 is connected to the control unit 17 for the overall carding and collection machine and receives from it the limiting values of the angle u03b1 for example u03b11 and u03b12 measured with respect to a reference line 18 preferably lying in the rotational plane of the rod 14 and passing through the intersection of the axis 13 with said plane these angles corresponding to the maximum and minimum allowable tension for the sliver the connection line 19 is used to transmit the relevant data in real time according to a modified embodiment of the present invention the sensor 16 for measuring the angular deviation of the sliver can be replaced by a sensor for measuring the angular momentum generated on the pivot 12 for instance on a transducer 20 which generates a signal corresponding to the torsional angular momentum u03c4 generated by the sliver 7 under tension deviated about the bar 11 which must be monitored and remain for example between limiting values u03c41 and u03c42 corresponding to the maximum and minimum allowable tension for the sliver in all cases the sliver tension is measured by sensors on the basis of the effect induced by this on the bar 11 in the direction of rotation indicated by the arrows b and c the signals generated by said sensors are transmitted to the control unit 17 which continuously compares the received values with the allowable limiting values which have been fed into it.