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. 1-11). 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. 1-12).
Figure 1-12.-Proper procedure for using adjustable
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.
Pipe Wrench (Stillson)
In rotating or holding round work, an adjustable
pipe wrench (Stillson) may be used (fig. 1-13). The
movable jaw on a pipe wrench is pivoted to permit a
gripping action on the work. This tool must be used
with discretion, as the jaws are serrated and always
make marks on the work unless adequate precautions
are observed. The jaws should be adjusted so the bite
on the work will be taken at about the center of the
Chain Pipe Wrench
A different type
large sizes of pipe,
of pipe wrench, used mostly on
is the chain pipe wrench (fig.
1-14). This tool works in one direction only, but can
be backed partly around the work and a fresh hold
taken without freeing the chain.
To reverse the
operation, the grip is taken on the opposite side of the
head. The head is double sided and can be reversed
when the teeth on one side are worn out.
Figure 1-13.-Adjustable pipe wrench.
Figure 1-11.-Adjustable wrenches.