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