BE SURE YOU ARE NOT DAYDREAMING
when you use the rotary scaler.
Needle scalers accomplish their task with an
assembly of individual needles impacting on a surface
hundreds of times a minute. The advantage of using
individual needles is that irregular surfaces can be
cleaned readily. See figure 1-69.
PORTABLE PNEUMATIC
IMPACT WRENCH
The portable pneumatic impact wrench (fig. 1-70)
is designed for installing or removing nuts and bolts.
The wrench comes in different sizes and is classified
by the size of the square anvil on the drive end. The
anvil is equipped with a socket lock, which provides
positive locking of the socket wrenches or
attachments. The wrench has a built-in oil reservoir
and an adjustable air valve regulator, which adjusts
the torque output of the wrench. The torque regulator
reduces the possibility of shearing or damaging
threads when installing nuts and bolts to their required
tension.
Nearly all pneumatic wrenches operate most
efficiently on an air pressure range of 80 to 90 psi. A
variation in excess of plus or minus 5 pounds is
serious.
Lower pressure causes a decrease in the
driving speeds, while higher pressure causes the
wrench to overspeed with subsequent abnormal wear
of the motor impact mechanisms.
The throttle lever, located at the rear of the
pneumatic wrench, provides the means for starting and
stopping the wrench.
Depressing the throttle lever
starts the wrench in operation. Upon release, the lever
rises to its original position, stopping the wrench.
The valve stem is seated beneath the pivot end of
the throttle lever. Most wrenches have a window cut
in the throttle lever so that the markings on the upper
surface of the valve stem will be visible. Two letters,
F and R, have been engraved on the head of the valve
stem to indicate the forward (clockwise) and reverse
(counterclockwise) rotation of the anvil. To change
from forward to reverse rotation, or vice versa, turn
the valve stem 180° until the desired marking is
visible through the window in the throttle lever.
When the valve stem is in proper position, the valve
stem pin engages a recess on the underside of the
valve stem, preventing accidental turning of the stem.
The air valve regulator is located at the bottom
and towards the rear of the wrench.
Using a
screwdriver and altering the setting of the air regulator
up to 90°, either to the right or left, reduces the torque
from full power to zero power.
Before operating the pneumatic impact wrench,
make sure the socket or other attachment you are
using is properly secured to the anvil. It is always a
good idea to operate the wrench free of load in both
forward and reverse directions to see that it operates
properly.
Check the installation of the air hose to
make sure it is in accordance with the manufacturer’s
recommendation.
Figure 1-70.-Pneumatic impact wrench.
1-41
Figure 1-69.-Needle impact scaler.
