Claims
- 1. A drill bit assembly for use with a down hole pneumatic hammer, comprising:
a driver; a pilot bit having a shank, a peripheral drilling surface, a lower surface, and a bore extending from the lower surface generally upwardly through the shank; coupling means rotatably coupling the driver to the pilot bit; underreamer arms rotatably mounted intermediate the driver and the pilot bit and including underreaming surfaces positionable outside the pilot bit perimeter; cam surfaces engageable with corresponding surfaces on the underreamer arms for deployment of the underreaming arms into an extended position, for locking the underreaming arms into the extended position, and for retracting the underreamer arms from the extended position by rotational movement between said driver and said pilot bit; surfaces defining at least one air passageway betweenan outer surface of the driver and the bore in the pilot bit.
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of U.S. application Ser. No. 09/702,277, filed on Oct. 30, 2000, which is a continuation-in-part of U.S. application Ser. No. 09/122,616, filed on Jul. 24, 1998, now U.S. Pat. No. 6,209,665 B1, issued on Apr. 2, 2001, which is a continuation-in-part of U.S. application Ser. No. 08/790,066, filed on Jan. 28, 1997, now U.S. Pat. No. 5,975,222, issued on Nov. 2, 1999, which is a continuation-in-part of U.S. application Ser. No. 08/674,123, filed on Jul. 1, 1996, now U.S. Pat. No. 5,787,999, issued on Aug. 4, 1998. The priority of these prior applications is expressly claimed and their disclosures are hereby incorporated by reference in their entirety.
Continuations (1)
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Number |
Date |
Country |
Parent |
09702277 |
Oct 2000 |
US |
Child |
10157352 |
May 2002 |
US |
Continuation in Parts (3)
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Number |
Date |
Country |
Parent |
09122616 |
Jul 1998 |
US |
Child |
09702277 |
Oct 2000 |
US |
Parent |
08790066 |
Jan 1997 |
US |
Child |
09122616 |
Jul 1998 |
US |
Parent |
08674123 |
Jul 1996 |
US |
Child |
08790066 |
Jan 1997 |
US |