be set down to form a pile is denoted by 8 the pile being denoted by 9 according to the invention a single column 10 is provided to enable the jaw 5 to be raised in the vertical plane and to ensure stable guidance for same in said vertical plane on two opposed sides the said column displays a guide section 11 with two opposed surface guides 11a on which there run guide wheels 12 supported on the trolley 4 the v shaped arrangement of the surface guides 11a or the guide wheels 12 provides optimum stability for the movement of the column 10 in the vertical plane these movements are effected in accordance with the invention by means of a rack 13 which is of one piece with the column 10 a pinion 14 engages with the rack 13 the former being splined to the output shaft 15 of a geared motor 16 supported on the trolley 4 the latter also supports another geared motor 17 for moving the trolley along the runways according to the invention said runways 3 are likewise equipped with a rack 18 which is engaged by a pinion 19 supported at the end of a shaft 20 actuated by said geared motor 17 on one of the runways 3 or on one side of the trolley 4 the latter exhibits at its ends a slide wheel 21 the other runway 3 is designed with a section 11 with opposed surface guides 11a in the shape of a v wherein guide wheels 12 engage in the same manner as that referred to above regarding.