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1,329,500
member, whereby the drill may be raised
and allowed to drop through the force of
gravitation at the end of every half revolu-
tion of the revoluble member, and means
5 on which the cable is wound, for raising the
drill tool or bit after completing the well,
and means to-effect a positive release of the
anti-frictional means from the ends of the
slot at the end of each half revolution of the
10 revoluble member and a tripping device for
the positive releasing means, and means on
the frame to act as a buffer for the walking
beam as the drill tool or bit drops, in order
to relieve the impacts of the walking beam.
15 6. In a well drilling rig, the combination
with a frame, of an oscillatory walking
beam fulcrumed thereon and provided with
a drilling tool suspended from its outer
end, revoluble means on the frame and pro-
20 vided with an elongated slot having offset
shoulders, at its opposite ends extending in
opposite directions, a connector on the inner
end of the beam and having a device engag-
ing said slot and adapted to engage said
shoulders every -half revolution of the re- 25
voluble means to tilt the beam for raising
the tool, elements carried by the revoluble
means adjacent the opposite ends of the slot,
each adapted to alternately cause a disen-
gagement of the device with one of the 30
shoulders every half revolution of the rev-
oluble means, to cause a positive drop of
the tool, and tripping means arranged in the
path of said elements to cause a positive
actuation of the elements. 35
In testimony whereof I hereunto affix my
signature in the presence of two witnesses.
ROBERT M. BRADFORD.
Witnesses:
A. BABIN,
WM. W. HUFF.