Patent ID: 8474537

Claim:
A wellhead connector for connecting an upper tubular member to a lower tubular member, the connector comprising: a housing adapted to be secured to the upper tubular member for sliding over the lower tubular member, the housing having an axis, an annular cam cavity, and an annular hydraulic chamber axially separated from the cam cavity by a stationary annular bulkhead; a plurality of dogs carried in the cam cavity, with the dogs being located within an aperture of the housing for movement from an unlocked position inward to a locked position for engagement with a profile on the exterior of the lower tubular member; a cam ring carried in the cam cavity for axial movement, the cam ring having an inner side which engages an outer side of each of the dogs for moving the dogs inward into the locked position; an annular primary piston carried in the hydraulic chamber for axial movement; an annular band extending downward from a lower side of the primary piston concentric with the axis of the housing, the band having inner and outer side walls joining the lower side of the primary piston with a bottom surface of the band, the band being symmetrical about a center line between inner and outer sides of the primary piston when viewed in a transverse cross-section: a plurality of rods connected between the primary piston and the cam ring for moving the cam ring in unison with the primary piston, each of the rods extending sealingly through a hole formed in the annular bulkhead; an annular secondary piston carried in the hydraulic chamber for axial movement independently from the primary piston and located below the primary piston; and an annular recess on an upper side of the secondary piston, the recess having a mating configuration for the band to receive and mate with the band while the primary and secondary pistons are in abutment with each other.