To set a conduit and insert the conduit into a sheath pipe which is a bent pipe as well as a straight pipe in operation only in a starting shaft, give free head turning property while keeping certain degree of stability in a conduit at the head, and suppress and stabilize rotation of the conduit while allowing deviation and bending of the conduit.
The conduit loosely fitted in two or more support plates connected by a plurality of flexible tie-rods across a join part is pressed by a rung in which a steel rope is locked and a pressing plate pivoted universally and is inserted into the sheath pipe. When the sum of friction force of the conduit and an internal wall of the support plate is F and the sum of friction force on a floor surface in the sheath pipe through a wheel or a guide and the support plate is R, the following relation, F>R, must be satisfied.
YAMAMURA YUKIO
KATSUMOTO SHINOBU
YAMATE KOICHI
