DCHP-1 Online
single-jack Mining 
n. a relatively small hammer used in single jacking.
See also: double-jack single-jacking
- 1961 The mechanization of mines in 1890--the replacing of hand-steel, single jack and double jack, by drilling machines--had created new problems. . . .
- 1964 The miner, working either a double-jack or single jack job, might worry about the sprags. . . .
- 1961 The mechanization of mines in 1890--the replacing of hand-steel, single jack and double jack, by drilling machines--had created new problems. . . .