Harnischfeger Technologies, Inc.

Curt L Silvestri

Jack W Nelson

David A Kaphingst

Marcia H Dalkert

A blasthole drill including a deck wrench for holding a drill pipe section to facilitate the unthreading of an adjoining drill pipe section from an overall drill pipe string. The deck wrench includes an engagement surface which is selectively engageable with an engagement surface of a drill pipe section to substantially prevent rotation of the drill pipe section in either direction about its longitudinal axis. The deck wrench is engageable with an upper drill pipe section so that a joint between the upper drill pipe section and a rotary head can be tightened when the rotary head is rotated in one direction. The deck wrench is engageable with a lower drill pipe section so that a joint between the lower drill pipe section and the upper drill pipe section can be broken when the rotary head is rotated in an opposite direction. The joint between the rotary head and the upper drill pipe section, once tightened, should be stronger than the joint between the upper drill pipe section and the lower drill pipe section. As a result, when the rotary head is rotated in order to break the joint between the upper drill pipe section and the lower drill pipe section, the joint between the rotary head and the upper drill pipe section will not break. The engagement between the deck wrench and the drill pipe is such that the drill pipe has a limited range of pivotal movement in either direction about its longitudinal axis to allow a certain amount of momentum to be transferred to the drill pipe by the rotation of the rotary head to enhance the tightening or loosening effect of the relevant joint.

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Mesa, AZ, United States of America

Curt L Silvestri