TM 1-1500-204-23-9
(3)
After use, wipe the screwdriver clean and
place in a rack or the tool box. For extended storage,
apply a light coat of oil to all metal surfaces and store it
in a dry place.
4-4. Wrenches. Wrenches are used for tightening or
removing nuts, bolts, or cap screws, and also for
gripping round objects such as pipe. They are made of
a
relatively
hard
substance,
such
as
chrome-
molybdenum steel, which enables them to withstand the
rigors of normal use.
a.
Types. Wrenches used in aircraft maintenance
can be generally categorized as open-end, box-end,
combination,
adjustable,
socket,
hexagonal,
and
spanner wrenches.
(1)
Open-end wrenches. Open-end wrenches
have two parallel jaws at each end of a bar, as shown in
figure 4-20. The jaws of an open-end wrench are
usually machined 15 degrees from parallel to the
centerline of the wrench, as shown in figure 4-21. The
two ends of each wrench fit consecutively-sized nuts
such as 3/8and 7/16-inch, 1/2and 9/16inch, and so on.
(2)
Box-end wrenches. Box-end wrenches
have a head on each end of a bar, as shown in figure 4-
22. The head completely surrounds the nut or bolt,
which decreases the chances that the wrench will slip off
the work. Box-end wrenches are available with 6-point
and 12-point openings. These openings are offset from
the shank at a 15-degree angle to allow clearance, as
shown in figure 4-23. A box-end wrench should be used
whenever possible because it provides the best
protection to both the user and the equipment. These
wrenches are sized the same as open-end wrenches.
(3)
Combination wrenches. The combination
wrench shown in figure 4-24 combines the best features
of the open-end and box wrench into a single wrench.
The size opening on the wrench is the same on both
ends, but one end has a box head and the other end has
an open-end head. The length of the wrench varies with
the size of the head. The box-end opening is offset
from the shank by 15 degrees.
(4)
Adjustable wrench. Adjustable wrenches
include crescent, auto, and pipe wrenches, shown in
figure 4-25. These wrenches are generally intended for
use on odd-sized nuts and bolts, and are adjusted by a
knurled worn gear, which moves the movable jaw to fit
the part. Adjustable wrenches are available in sizes
ranging from 4 to 24 inches in length. The jaw capacity
is proportional to the handle length.
Figure 4-20. Open-End Wrench
Figure 4-21. Open-End Wrench Jaw Offset
Figure 4-22. Box End Wrenches
Figure 4-23. Box-End Wrench Offset
(5)
Socket wrenches. Socket wrenches
consist of a socket and a handle.
(a)
Sockets. Sockets are round metal
sleeves with a square opening in one end for insertion of
a handle, and a 6-point or 12-point wrench opening in
the other, as shown in figure 4-26. They are available in
common (short) and deep (long) lengths. The drive
4-8
