Patent ID: 8313070

Claim:
A base-clamp assembly for supporting an instrument-support apparatus having a shank extending adjacent to an equipment-mounting rail for supporting instruments relative to a patient position adjacent to the rail, the base-clamp assembly comprising: a base; a shank clamp for attaching the shank to the base; a rail clamp having a first rail jaw fixedly supported relative to the base, and a second rail jaw mounted for pivoting relative to the base and opposing and movable relative to the first rail jaw, the first and second rail jaws forming a rail opening, the second rail jaw being movable between an open position in which the rail opening is sized for receiving a rail and a closed position in which the rail jaws securely hold the rail; and an actuator assembly operable for moving the second rail jaw relative to the first rail jaw, the actuator assembly including a first force-applying element movable relative to the base and the second rail jaw, for applying a first force to the second rail jaw tending to move the second rail jaw toward the closed position, and a drive assembly manipulable for moving the first force-applying element relative to the base, wherein the drive assembly includes a frame movable relative to the base and the first force-applying element includes a roller mounted to the frame for rotation about a roller axis, the roller applying the first force to the second rail jaw.