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
molybdenum steel, which enables them to withstand the
rigors of normal use.
Types. Wrenches used in aircraft maintenance
can be generally categorized as open-end, box-end,
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.
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.
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.
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
Socket wrenches. Socket wrenches
consist of a socket and a handle.
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