ladder drilling

ladder drilling

[′lad·ər ‚dril·iŋ]
(mechanical engineering)
An arrangement of retractable drills with pneumatic powered legs mounted on banks of steel ladders connected to a holding frame; used in large-scale rock tunneling, with the advantage that many drills can be worked at the same time by a small labor force.
References in periodicals archive ?
Mother-of-two Kathleen Hughes, 66, said: "I came home from shopping and found a workman up a ladder drilling away.