The invention relates to a rotary lobe pump for conveying solids-laden fluids engendered in agriculture, in which the conveyed fluid volume flow adapts itself to different operating modes. For improved self-priming, the rotary lobe pump is designed for vertical mounting of the rotary lobes, wherein an angular gear is provided. The rotary lobes are mounted in a topside or underside cover, wherein the axes of the rotary lobes are vertically oriented. Using one of the covers, the rotary lobes can be vertically removed and maintained without having to dismantle other pump components from the pump housing. The rotary lobes can also be removed together with the angular gear as an integral pump component using one of the covers.