the operating condition in the operating condition furthermore the frame part 31 is mounted on supports 3 a ladder 21 completes the operating condition a strut 30 serves as additional strengthening for the frame part 31 a similar task is performed by supports 6 shown in fig1 but omitted from the other drawings for the sake of clarity the charge box 12 is shown in its metering position in fig3 in this position it is disposed beneath the metering flaps the path of the charge box comprises several sections the lower section in which the charge box is shown in fig3 is slightly inclined and is concealed by the frame sections 98 adjacent this section is an intermediate section 59 which is inclined at about 20 u00b0 and has the task of facilitating the withdrawal of the charge box from beneath the metering flaps and of creating a transition to the section of the charge box path which consists of the parts 13 14 and is inclined at about 60 u00b0 on the other hand the section 59 reduces the speed of the charge box as it moves down the path so that the charge box runs on to the lowermost section at a.