Abstract: A flexible tube formed by interlocking a first edge of a single strip material with a second edge of the strip material that adjoins the first edge by spirally winding the strip material, allowing passage of a solid object, and having a specific length, wherein the flexible tube has a shape of an ellipse in cross-section perpendicular to a direction of the passage, the ellipse having a shape that prevents a torsional force caused by torsion from propagating to a part on which a torsional force concentrates in a flexible tube with a circular cross-section perpendicular to the direction of the passage, and wherein the ellipse has a shape that creates a space for a cable between an outer surface of the ellipse and an inner surface of a covering material having a circular cross-section with a diameter greater than a length of a major axis of the ellipse.

Abstract: A flexible tube formed by interlocking a first edge of a single strip material with a second edge of the strip material that adjoins the first edge by spirally winding the strip material, allowing passage of a solid object, and having a specific length, wherein the flexible tube has a shape of an ellipse in cross-section perpendicular to a direction of the passage, the ellipse having a shape that prevents a torsional force caused by torsion from propagating to a part on which a torsional force concentrates in a flexible tube with a circular cross-section perpendicular to the direction of the passage, and wherein the ellipse has a shape that creates a space for a cable between an outer surface of the ellipse and an inner surface of a covering material having a circular cross-section with a diameter greater than a length of a major axis of the ellipse.

Abstract: In a flexible pipe having shape retaining capabilities, a first pipe is provided having a first base wire and a first subsidiary wire, the first base wire being wound in a spiral manner, the first subsidiary wire externally covering the first base wire and being fit into an external valley of the first base wire, and a second pipe having a second base wire and a second subsidiary wire, the second base wire being wound in a spiral manner in an opposite direction from the first base wire, the second subsidiary wire externally covering the second base wire and being fit into an external valley of the second base wire. The second pipe being provided inside and in contact with the first pipe. When a torsional force is applied to the first pipe, the second pipe generates a bearing force against the torsional force.

Abstract: In a flexible pipe having shape retaining capabilities, a first pipe is provided having a first base wire and a first subsidiary wire, the first base wire being wound in a spiral manner, the first subsidiary wire externally covering the first base wire and being fit into an external valley of the first base wire, and a second pipe having a second base wire and a second subsidiary wire, the second base wire being wound in a spiral manner in an opposite direction from the first base wire, the second subsidiary wire externally covering the second base wire and being fit into an external valley of the second base wire. The second pipe being provided inside and in contact with the first pipe. When a torsional force is applied to the first pipe, the second pipe generates a bearing force against the torsional force.