Expansion bolt

1. A method for releasably gripping a hole surface comprising:

providing an expansion bolt comprising a collar, a cable slidingly running through said collar, a first chock connected to a first end of said cable, a second chock connected to said collar by a flexible rod, for cooperation with said first chock such that relative translation of said first chock in a first direction causes said first and second chocks to slidingly assume relative positions corresponding to an expanded configuration of the expansion bolt that grips the hole surface, and a cleaning bushing slidingly connected to said cable and captivated between said collar and first chock; said cleaning bushing being adapted to, in response to application of an impact force to said cleaning bushing, transmit a force to said first chock that results in a translation of said first chock relative to said second chock in a second direction opposite said first direction, to release said grip; wherein said cleaning bushing is adapted for transmitting to said first chock a substantial resulting force, and for transmitting to the second chock substantially no force, in response to the application of said impact force; and said cleaning bushing is adapted to translate relative to the collar so as to cause the release of said grip;

inserting said chocks in a hole and causing the expansion bolt to adopt said expanded configuration;

moving said cleaning bushing so as to make contact with said first chock;

striking said cleaning bushing with a tool in said second direction so as to cause the expansion bolt to relax said grip; and

pulling the expansion bolt out from the hole.

2. An expansion bolt for releasably gripping a hole surface, comprising:

a collar;

a cable slidingly running through said collar;

a first chock connected to a first end of said cable;

a second chock connected to said collar by a flexible rod, for cooperation with said first chock such that relative translation of said first chock in a first direction causes said first and second chocks to slidingly assume relative positions corresponding to an expanded configuration of the expansion bolt that grips the hole surface;

a cleaning bushing slidingly connected to said cable and captivated between said collar and first chock; said cleaning bushing being adapted to, in response to application of an impact force to said cleaning bushing, transmit a force to said first chock that results in a translation of said first chock relative to said second chock in a second direction opposite said first direction, to release said grip;

wherein said cleaning bushing is adapted for transmitting to said first chock a substantial resulting force, and for transmitting to the second chock substantially no force, in response to the application of said impact force; and said cleaning bushing is adapted to translate relative to the collar so as to cause the release of said grip.

3. The expansion bolt of claim 2 , wherein said first chock is frustoconical.

4. The expansion bolt of claim 2 , further comprising a handle connected to a second end of said cable and a spring for biasing said handle away from said collar toward said expanded configuration of the expansion bolt.

5. The expansion bolt of claim 4 , wherein said first chock is frustoconical.

6. The expansion bolt of claim 2 , wherein said cleaning bushing is adapted to come into abutment with said one of said first and second chocks for transmitting said resulting force thereto.

7. The expansion bolt of claim 6 , further comprising a handle connected to a second end of said cable and a spring for biasing said handle away from said second chock toward said expanded configuration of the expansion bolt.

8. The expansion bolt of claim 7 , wherein said first chock is frustoconical.

9. The expansion bolt of claim 2 , further comprising a third chock, substantially identical to and azimuthally spaced apart from said second chock, and adapted for cooperation with said first chock such that relative translation of said first chock in said first direction causes said first and third chocks to slidingly assume relative positions corresponding to said expanded configuration of the expansion bolt.

10. The expansion bolt of claim 9 , wherein said first chock is frustoconical.

11. The expansion bolt of claim 9 , further comprising a handle connected to a second end of said cable and a spring for biasing said handle away from said collar toward said expanded configuration of the expansion bolt.

12. The expansion bolt of claim 11 , wherein said first chock is frustoconical.

13. The expansion bolt of claim 9 , wherein said third chock is connected to said collar.

14. The expansion bolt of claim 13 , further comprising a handle connected to a second end of said cable and a spring for biasing said handle away from said collar toward said expanded configuration of the expansion bolt.

15. The expansion bolt of claim 14 , wherein said first chock is frustoconical.

16. The expansion bolt of claim 13 , wherein said outer surfaces of said second and third chocks each include respective slip-resistant gripping patterns for increasing the slip-resistance of said grip, wherein said gripping patterns comprise spaced-apart, substantially annular portions of the respective said outer surfaces of said second and third chocks.

17. The expansion bolt of claim 16 , further comprising a handle connected to a second end of said cable and a spring for biasing said handle away from said collar toward said expanded configuration of the expansion bolt.

18. The expansion bolt of claim 17 , wherein said first chock is frustoconical.

19. The expansion bolt of claim 13 , wherein said second and third chocks are connected to said collar by respective flexible rods.

20. The expansion bolt of claim 19 , further comprising a handle connected to a second end of said cable and a spring for biasing said handle away from said collar toward said expanded configuration of the expansion bolt.

21. The expansion bolt of claim 20 , wherein said first chock is frustoconical.