piston drill

piston drill

[′pis·tən ¦dril]
(mechanical engineering)
A heavy percussion-type rock drill mounted either on a horizontal bar or on a short horizontal arm fastened to a vertical column; drills holes to 6 inches (15 centimeters) in diameter. Also known as reciprocating drill.
References in periodicals archive ?
In previous editions of the Balance Piston drills, as many as 2,000 Filipino soldiers from different branches of the armed services took part.