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a. A light, mobile, and fast-cutting drill in which the bit does not
reciprocate but remains against the rock in the bottom of the hole,
rebounding slightly at each blow. There are three types of hammer drills;
drifter, sinker, and stoper. Lewis
b. A development of the piston drill in which the drill steel is not
attached to the piston but remains in the hole, the piston delivering a
rapid succession of light hammer blows. The drill steel is frequently
hollow so that air or water may be driven through to cool the bit and
clean the hole. Rotation of the bit is automatic. Also known as
jackhammer. Barger
c. A percussive drill. BS, 12
d. A rock drill powered by compressed air that reciprocates a free piston,
causing it to strike the shank of the drill steel. When of light
construction, a hand hammer drill, otherwise supported on a tripod or bar.
Pryor, 3
Source:
Dictionary of Mining, Mineral, and Related Terms
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