applies glue to the spine of topmost folded product 20 b while the raceway together with the folded products continues to move underneath glue application heads 30 in arrow direction a a control unit 36 a gluing unit 37 and a sensor 34 control the quantity of adhesive and the instant of its application for this purpose glue application head 30 is connected to lines 38 and 38 line 39 carries the adhesive and lines 38 transmit the control pulses and supply the compressed air for the adhesive application sensor 34 detects the front edge of the folded product and transmits a signal via line 41 for further processing to control unit 36 which controls the length of the glue line to be applied and the interval in which no glue is applied a vertically adjustable hold down device 40 is provided for holding down folded product 20 b during glue application following the application of glue to spine 32 the group of folded products 18 fig1 as already described in fig1 is conveyed to a station 26 where a cover is put on the adhesive to join all folded products to one another it is therefore advantageous to provide the gluing station as the last station immediately before the location where the cover is placed on the raceway once the cover is placed on the adhesive the glued product is preferably conveyed to a pressure applying station 29 where cover 22 is pressed onto the remaining folded.