TM 5-3820-241-34
Section III. DRIFTER DRILL
5-9. General
operating principles involved in the action of the
drill engine. First, the principle that makes the
a. Description. The pneumatic drill engine is a
piston reciprocate in the cylinder, and second, the
heavy duty percussion machine designed for deep
principle that causes the drill steel to rotate.
hole drilling in hard rock. The drill incorporates a
(1) Piston Reciprocation. Back and forth
dual rotation assist unit integral with the drill to
movement of the piston is affected by a self-
p r o v i d e a fast method for coupling and un-
acting or automatic valve that admits air at the
coupling the drill steels, and to furnish a power
proper instant, first to one end of the cylinder
a s s i s t to normal rifle bar rotation. The dual
then to the other end. Figure 5-5 illustrates the
rotation unit consists of an independent vane type
i n v o l v e d portion of the drill engine in cross
air motor geared to rotate the chuck in either
direction. Operating controls for the drill and
section. The left hand view shows the piston at
the top part of the cycle, and in the right hand
allied functions are mounted on the feed.
view, the piston is in the bottom part of the cycle.
b. Theory of Operation. There are two basic
ME 3820-241-34/5-5
Figure 5-5. Drifter drill valve operation.
(2) Value Operation. In figure 5-5 (left hand
port that allows air to flow through the kick port
v i e w ) the piston is shown moving to the up-
to the backside of the valve. This pressure causes
permost part of the cycle. Just before it reaches
the valve to close the air supply to the back end of
the top of the chamber it uncovers the air kick
the cylinder and to admit air to the front end