Patent ID: 7874352
Filing Date: 2011-01-25
Classification: E21B

Abstract:
1. An apparatus for gripping a tubular for use with a top drive, comprising: a connection at one end for rotationally fixing the apparatus relative to the top drive; one or more gripping members at a second end for gripping the tubular; a plurality of fluid operated actuators simultaneously operable to move and hold the gripping members in contact with the tubular, wherein the plurality of fluid operated actuators include a first actuator and second actuator configured for selective simultaneous actuation or independent actuation such that the second actuator switches to independent actuation in the event of fluid failure of the first actuator; and a backup assembly adapted to maintain the gripping member in contact with the tubular, wherein the backup assembly comprises a check valve operable in conjunction with the first actuator to ensure the first actuator remains operable in the event of fluid failure.