continuously running during operation the shaft 20 is driven in a manner controllable by means of a clutch and brake that is intermittently in the direction of the dashed arrow the clutch and brake are arranged so that in the presence of a control signal of a control circuit 60 which is explained in greater detail with reference to fig2 the shaft 20 is connected with the drive and in the absence of the control signal braked with interruption of this connection the edges pointing in the transport direction leading edges of the letters contained in the stack apply more or less closely against an abutment wall 40 which leaves a gap or stack exit free toward the drawoff belt 25 permitting the passage of the letters in the transport path of the letters a pair of continuously driven transport rollers 43 and 44 are arranged by which the letters are moved on positively as soon as they have come into their pickup zone these transport rollers serve here in addition as guide rollers of conveyor belts 48 and 49 which are trained in the transport direction around additional guide rollers 50 and 51 while the driven transport roller 43 is mounted fixed the transport roller 44 is mounted flexible in known manner e g on a pivotable lever but for greater simplicity this is not shown in the drawings along the transport path of the letters contiguous to the stack exit abutment wall 40 a.