Title:
DRILL STRING HOLDER FOR ROCK DRILL
Document Type and Number:
Japanese Patent JPS5278701
Kind Code:
A
Abstract:
A drill string holder for a rock drilling machine has two jaws opposite each other for gripping a drill string, e.g. the drill string in core drilling with a diamond drill bit. The jaws are forced into their gripping positions by means of a heavy spring. A first selectively actuatable hydraulic piston is arranged to overcome the spring and permit the jaws to release their grip. A selectively actuatable second piston is located inside the first piston. By means of the second piston, the operator can apply a selectively variable force to the jaws when the jaws are released from the spring. This permits the operator to let the drill string gently down into the bore hole by applying a controlled braking force on it.
Inventors:
YON ARUNE RAGERUSHIYUTATSUTO
Application Number:
JP14792476A
Publication Date:
July 02, 1977
Filing Date:
December 10, 1976
Export Citation:
Assignee:
ATLAS COPCO AB
International Classes:
E21B7/02; E21B19/08; E21B19/086; E21B19/16; (IPC1-7): E21B3/00
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