PURPOSE: To obtain the subject equipment capable of thoroughly dropping mud intermixed in crops during conveying and capable of protection of clogging, etc., of a transfer spiral by making mud discharge slits in the direction intersecting to the axial direction of the transfer spiral of a receiving conduit on the above-mentioned receiving conduit at the bottom part of a grading-wind duct of a thresher.

CONSTITUTION: A grain-receiving conduit 18 having a transfer spiral 20 is attached to the bottom part of a grading-wind duct 17 of a thresher and mud discharge slits 22 are simultaneously formed on the grain-receiving conduit 18 in the direction intersecting to the axial direction of the transfer spiral 20. Thereby, thorough dropping of only mud through the slits 22 is enabled during transfer of grains intermixed with the mud and received by the grain-receiving conduit 18 using the transfer spiral 20.