<p>The machine has a locking device designed as a slide valve (10) that is inserted in a housing (2) above a bucket wheel (6) and arranged between a lower end of a supply container and the bucket wheel. A wall of the housing has a gap (9), and a sealing valve is provided for sealing the gap. The slide valve is inserted into the housing for locking the supply of material from the storage container to the bucket wheel after removing the sealing valve. The sealing valve is fastened to the housing in the sealing position.</p>
