1. Harvesting unit for corn or the like for a harvesting attachment of a harvesting machine having a working slot (10), in which two retracting rollers (26, 27) are arranged to rotate towards each other, characterized in that the retracting roller (26) has a section (28) with a spiral envelope blade ( 29) .2. A block according to claim 1, characterized in that the other retractor roller (27) has a section (30) with a spiral-shaped envelope blade (31) or a spiral-shaped envelope bar (34) .3. A block according to claim 2, characterized in that the blade (29) and the other blade (34) or strip (37) penetrate each other. 4. A block according to claim 2 or 3, characterized in that there is a corrugation (35) between the sections (33) of the spiral envelope of the bar (34) of the other retracting roller (27). Block according to one of paragraphs. 1-3, characterized in that one or both of the retracting rollers (26, 27) have a smooth retracting zone (36) .6. Block according to claim 4, characterized in that one or both of the retracting rollers (26, 27) have a smooth retracting zone (36) .7. Block according to one of paragraphs. 1-3 or 6, characterized in that one or both of the retracting rollers (26, 27) have a retracting zone (36) with a spiral envelope bar (37) .8. A block according to claim 4, characterized in that one or both of the retracting rollers (26, 27) have a retracting zone (36) with a spiral envelope strip (37) .9. A block according to claim 5, characterized in that one or both of the retracting rollers (26, 27) have a retracting zone (36) with a spiral envelope strip (37) .10. Block according to one of paragraphs. 1-3, 6, 8 or 9, characterized in that the retracting zone (36) of one or both of the retracting rollers (26, 27) is conical. A block according to claim 4, characterized in that the retracting zone (36) of one or both of the retracting rollers (26, 27) is conical. A block according to claim 5, characterized in that the retracting zone (36) of one o
