TM 5-3820-241-34
ft-lb blow to the drill steel shank. This is known
(4) Assist Rotation Motor. To assist the rifle
as upstroke rotation. The 40 designates the total
bar rotation, the drill engine has an air driven
travel of the piston required to make one full
vane motor. The motor is geared to the chuck
revolution. Since the rifle bar governs rotation of
bushing to provide additional torque.
the piston and the steel, this can be expressed in
(5) Reverse Rotation. The vane air motor is a
another manner. If a rifle bar were made long
reversing motor. When the reverse rotation lever
enough, the spiral flutes would make on complete
is activated, a rotation release ring collars the
turn around the bar in 40 inches.
ratchet mechanism allowing the rifle bar to rotate
in either direction. The same control reverses the
5-10. Drifter Drill Removal and Disassembly
rotation of the vane air motor which is geared to
a. Removal.
the chuck bushing resulting in reverse rotation. It
(1) Position the rock drill feed mechanism in
should be noted that in reverse rotation, all the
the horizontal position.
torque is provided by the vane air motor only.
(2) Disconnect the air supply at the
(6) Upstroke Rotation. The drill engine has a
l u b r i c a t o r fitting. Open the blow handle and
40 upstroke rotation. As explained in paragraph 5
release all air from the system.
b (3), the rotation system rotates the piston on
( 3 ) Remove the drifter drill assembly in
the up or return stroke. The down or power stroke
numerical sequence as illustrated in figure 5-7.
has the single purpose of imparting the maximum
5-9