초록 ▼

An inner duct is disclosed which can fit inside a duct and extend along a length thereof for receiving communication cable, particularly a light-guide cable. The inner duct has a continuous side wall with protruding ribs on the inside and outside surfaces to maintain an effective supply of lubricant

An inner duct is disclosed which can fit inside a duct and extend along a length thereof for receiving communication cable, particularly a light-guide cable. The inner duct has a continuous side wall with protruding ribs on the inside and outside surfaces to maintain an effective supply of lubricant during the installation of the inner duct and cable in the inner duct. The ribs on the inside surface of the inner duct guide the cable during the placement operation. It is preferred to install a plurality of inner ducts into a duct during which the ribs on the inner duct interlock with one another to prevent spiraling. The ribs also facilitate the dissipation of heat due to friction and ambient sources of heat.

대표청구항 ▼

A radially stable tubular apparatus to protect transmission cable from damage and aid in its installation, said apparatus comprising: an open-ended, elongated hollow tube having a side wall made of synthetic plastic material with a continuous internal surface comprised of spaced-apart and generally

A radially stable tubular apparatus to protect transmission cable from damage and aid in its installation, said apparatus comprising: an open-ended, elongated hollow tube having a side wall made of synthetic plastic material with a continuous internal surface comprised of spaced-apart and generally protruding internal ribs extending along the length of the internal surface of the tube, said internal ribs having a height and being spaced apart a distance sufficient to contain a supply of lubricant therebetween and form the only areas of frictional contact with the transmission cable whereby the tube is adapted to support transmission cable on its internal ribs as the cable is inserted therethrough and thereby reduce the frictional contact between the tube and the cable; an external surface on the side wall having external protruding ribs extending along the length of the tubing, the external ribs being spaced about substantially the entire external surface of the tube so that such external protruding ribs are adapted to touch the surface with which the tube is in contact, wherein there are more internal ribs than external ribs and the external ribs are spaced to hold lubricant therebetween.