A handy all-round wrench that is generally
included in every toolbox is the adjustable open-end
wrench. This wrench is not intended to take the place of
the regular solid open-end wrench. Additionally, it is
not built for use on extremely hard-to-turn items. Its
usefulness is achieved by being capable of fitting
odd-sized nuts. This flexibility is achieved although
one jaw of the adjustable open-end wrench is fixed,
because the other jaw is moved along a slide by a
thumbscrew adjustment (fig. 1-35). By turning the
thumbscrew, you can adjust the jaw opening to fit
various sizes of nuts.
Adjustable wrenches are available in varying sizes,
normally ranging from 4 to 24 inches in length. The
size of the wrench selected for a particular job is
dependent upon the size of the nut or bolt head to which
the wrench is to be applied.
Adjustable wrenches are often called "knuckle
busters," because mechanics frequently suffer these
consequences as a result of improper usage of these
tools. To avoid accidents, follow four simple steps.
First, choose a wrench of the correct size; that is, do not
pick a large 12-inch wrench and adjust the jaw for use
on a 3/8-inch nut. This could result in a broken bolt and
a bloody hand. Second, be sure the jaws of the
correct-size wrench are adjusted to fit snugly on the nut.
Third, position the wrench around the nut until the nut
is all the way into the throat of the jaws. If the wrench is
not used in this manner, the result is apt to be as bloody
as before. Fourth, pull the handle toward the side
having the adjustable jaw (fig. 1-36). This will prevent
the adjustable jaw from springing open and slipping off
the nut. If the location of the work will not allow for all
four steps to be followed when using an adjustable
wrench, then select another type of wrench for the job.
Union Nut Wrench
The adjustable union nut wrench (fig.1-37) is used
to assemble and disassemble pipe union nuts. The
adjustable jaws are held in place by removable nut and
bolt and is adjusted to proper size before each use.
In rotating or holding round work, an adjustable
pipe wrench (Stillson) may be used (fig. 1-38). The
Figure 1-36.Proper procedure for using adjustable
Figure 1-35.Adjustable wrenches.
Figure 1-37.Union nut wrench.
Figure 1-38.Adjustable pipe wrench.