Drilling shaft abutting apparatus

摘要

A drilling shaft abutting apparatus is disclosed herein. The apparatus includes a plate having an arcuate edge. The arcuate edge is configured to at least partially encircle a drilling shaft. The apparatus also includes a first blade mounted on the plate for pivoting movement between a first retracted position and a first fully-pivoted position. The first blade passes across the arcuate edge during movement between the first retracted position and the first fully-pivoted position. The first blade prevents items from falling down a hole at least partially occupied by the drilling shaft. The apparatus includes at least one actuator operable to selectively urge the first blade to at least one of the first retracted position and the first fully-pivoted position.

主权项

1. A drilling shaft abutting apparatus comprising:
a plate having an arcuate edge, said arcuate edge configured to at least partially encircle a drilling shaft; a first blade mounted on said plate for pivoting movement between a first retracted position and a first fully-pivoted position wherein said first blade passes across said arcuate edge during movement between said first retracted position and said first fully-pivoted position and wherein said first blade prevents items from falling down a hole at least partially occupied by the drilling shaft; at least one actuator operable to selectively urge said first blade to at least one of said first retracted position and said first fully-pivoted position; and a second blade mounted on said plate for pivoting movement between a second retracted position and a second fully-pivoted position wherein said second blade and said first blade are engaged for at least one range of concurrent motion and for at least one range of lost motion in which only one of said first and second blades is moving.