PURPOSE: To make work for the inside of a duct part performable from an opening by forming a conveyor with a section C-shaped self-propelled car guide, forming an opening for self-propelled car traveling, and the duct part, and installing a slit, to be interconnected to the inside of the duct parts, in the side of the guide part.
CONSTITUTION: In a duct part 33, there are provided with plural pieces of wiring 25 being connected to feeding rails 41A and 41B or connected to the rail side equipment 42, and they are set up an inner surface of this duct part 33. And, with width corresponding to width l of the duct part 33, a groove 28 is formed in a ceiling 27, and the duct part 33 is inset in this groove 28 whereby a rail device 30 is set up on the ceiling 27 in turning an opening 31 downward toward the chamber inside. Consequently, when the wiring into the duct part 33 and the rail side equipment 42 are varried out and, what is more, maintenance, inspection, etc., for them 25 and 42 are performed, first removal of insulating covers 49 and 49a takes place. And, various jobs can be easily done by reducing manhours through the opening 31 and a slit 39.