CraneE.| Prospecting, Mining and Milling Machinery. 221 
of the three general forms of drills: The first type is shown 
in figure 28, and represents the movement which is found on 
several makes of rigs. The rope is wound on adrum, UC, 
which is provided with a friction brake, B. It passes from 
the drum through the pulleys on the oscillating beam, A, to 
the drill. When the drive wheel turns, the outer end of the 
beam moves up and down, thus raising and lowering the 
tool. The stroke of the drill is regulated by increasing or 
decreasing the radius of the crank. The tool is lowered by 
loosening the brake and running off sufficient rope from the 
drum, C, then tightening or resetting the brake, when work 
may be resumed. 
k 
TO DRILL 
CRANE, 
Fig. 29. A form of actuating mechanism for a self-contained drilling outfit. 
The second form is shown in figure 29. It represents a 
common movement. A chain sixteen or eighteen feet long is 
partially wound on adrum, M, provided with a ratchet. The 
chain passes through a pulley on the beam, JN, and the end 
is attached to a clamp which is fastened to the drill rope. 
As the drive wheel revolves, the crank, 0, which has two 
rollers near the end, strikes the end of the beam, JN, and- 
forces it down, thus raising the tool. 
