Apparatus for supporting and rotating a down hole tubular

A drive apparatus for an earth boring apparatus including a derrick which defines a pair of spaced rails, said drive apparatus comprising:

• a support member;
• means for guiding the support member along the rails of the derrick such that the support member is movable along the derrick;
• a shaft adapted for connection to a drill string to support the weight of the drill string;
• a first bearing mounted between the support member and the shaft such that vertical loads on the shaft are transmitted via the first bearing to the support member, said first bearing adapted to accommodate a selected degree of variations in the axis of rotation of the shaft associated with rotation of assymetrical down hole tubulars without damaging the first bearing;
• rotary drive means for rotating the shaft;
• a second bearing mounted between the shaft and the rotary drive means to align the rotary drive means precisely on the shaft adjacent the support member such that the rotary drive means follows the lateral movement of the shaft as it turns in the first bearing;
• and
• a torque arm mounted between the rotary drive means and the support member such that the rotary drive means is substantially prevented from rotating about the support member in a plane perpendicular to the longitudinal axis of the shaft but the rotary drive means is free to follow lateral movement of the shaft as it turns in the first bearing without subjecting the second bearing to excessive skew forces.

A drive apparatus for an earth boring drilling apparatus including a derrick which defines a pair of spaced rails, said drive apparatus comprising:

• a support member having an opening passing therethrough;
• means for guiding the support member along the rails of the derrick such that the support member is movable along the length of the derrick;
• a first bearing mounted within the support member adjacent the opening therein;
• a shaft adapted for connection to a drill string to support the weight of the drill string, said shaft mounted in the first bearing such that vertical loads on the shaft are transmitted via the first bearing to the support member;
• a rotary drive unit including a drive motor drivingly engaged to a transmission which is enclosed in a transmission case having an opening passing therethrough, said rotary drive unit positioned on the shaft adjacent the support member such that the shaft passes through the opening in the transmission case;
• a second bearing mounted to the shaft within the transmission case to cause the rotary drive unit to maintain precise alignment with the shaft as the shaft rotates in the first bearing;
• a torque arm mounted between the rotary drive unit and the support member to prevent rotation of the rotary drive unit with respect to the support member in a plane perpendicular to the longitudinal axis of the shaft;
• said first bearing adapted to accommodate shifts in the axis of rotation of the shaft associated with the rotation of assymetrical down hole tubulars without damaging the first bearing;
• said torque arm mounted to the rotary drive unit and the support member to permit the rotary drive unit to follow lateral movement of the shaft as it rotates in the first bearing without applying excessive skew forces to the second bearing.