Liner hanger system

A liner hanger system, comprising

• a joint of casing adapted to be connected as part of an outer casing installed within a wellbore,
• a liner adapted to be lowered within the outer casing,
• the bore of said casing joint having vertically spaced, upwardly facing upper and lower landing surfaces formed on an intermediate portion thereof, and a lower annular recess separated from the lower landing surface by a lower annular restriction,
• the said liner including a tubular body having a recess formed thereabout with an annular groove formed in its lower end,
• a hanger comprising a circumferentially expandible and contractible C-ring disposed within and closely about the liner recess when in its normally contracted portion,
• said C-ring having teeth formed thereabout for landing on the landing surfaces of the casing joint when in its expanded portion, and a lower end fitting within the groove when in its contracted portion to permit the liner to be lowered through the outer casing,
• said C-ring being expandable, upon relative vertical movement with respect to the liner, so as to release its lower end from the groove and thereby permit the ring to expand outwardly against the outer casing,
• whereby, upon continued relative movement of the liner and ring, the teeth will move into a position in which they expand outwardly into landed positions on the landing surfaces to permit the liner to be suspended therefrom,
• said liner having a downwardly facing shoulder for landing on the upper end of the C-ring when expanded and an outward enlargement beneath the shoulder to fit within the upper end of the ring so as to hold the ring expanded.