To perform those of maintenance, inspection and cleaning operations mechanically as traveling without walking on a corridor by attaching a workbench forming a nearly horizontal working plane in a mounting state detachably to an endless belt where an upper part slides on the upper part of a platelike member and forms a traveling corridor.

When inspection is carried out, an operator gets on an endless belt 7 and performs it as traveling along a belt conveyor. Likewise, when repairing is carried out, a workbench 10 is mounted on the endless belt 7, and a slab 10b of this workbench 10 is superposed on a flat bar 11, aligning a hole 10f of this slab 10b with a tapped hole 12 of the flat bar 11, and they are secured tight enough by a bolt 14. Then, the operator rides on the workbench 10 together with repair parts, and a motor is driven, the endless belt 7 is rotated, moving it up to a necessary spot. Cleaning of a moving corridor, namely, a surface of this endless belt 7 is carried out periodically by way of driving this endless belt 7 into no-load running.