Thrust-bearing assembly

A thrust-bearing apparatus, comprising:

• a rotor comprising at least one bearing element including a rotor bearing surface;
• a stator comprising at least one bearing element including a stator bearing surface, the stator positioned so that the stator bearing surface opposes the rotor bearing surface;
• and
• wherein at least one of the rotor or the stator comprises:
• a seat including a generally spherical surface at least partially defining a recess;
• a bearing support positioned within the recess, the bearing support including a generally spherical surface configured so that the bearing support is capable of movement within the recess;
• at least one bearing element mounted to the bearing support;
• a motion-limiting structure configured to limit relative movement between the bearing support and the seat;
• and
• wherein the motion-limiting structure does not extend between the generally spherical surface of the seat and the generally spherical surface of the bearing support.

A motor assembly for use in drilling subterranean formations, comprising:

• a motor operable to apply torque to a rotary drill bit, the motor operably coupled to a thrust-bearing apparatus, the thrust-bearing apparatus comprising:
• a rotor comprising at least one bearing element including a rotor bearing surface;
• a stator comprising at least one bearing element including a stator bearing surface, the stator positioned so that the stator bearing surface opposes the rotor bearing surface;
• and
• wherein at least one of the rotor or the stator comprises:
• a seat including a generally spherical surface at least partially defining a recess;
• a bearing support positioned within the recess, the bearing support including a generally spherical surface configured so that the bearing support is capable of movement within the recess;
• at least one bearing element mounted to the bearing support;
• a motion-limiting structure configured to limit relative movement between the bearing support and the seat;
• and
• wherein the motion-limiting structure does not extend between the generally spherical surface of the seat and the generally spherical surface of the bearing support.