TM 9-243
TYPES AND USES - Continued
OPEN END WRENCHES (Cont)
The S-Shape wrench has a 22-1/2 degree offset. It is
used to reach around obstructing objects.
Ignition wrenches have the same size jaw opening on
both ends. However, one end of this wrench is offset 15
degrees and the other end is offset 60 degrees. Ignition
wrenches are smaller in size, as they are used to
remove components of automotive ignition systems.
BOX WRENCHES
A box wrench surrounds the nut, bolt head, or stud on all
sides. It is available with both 6-point and 12-point
openings. The 12-point opening is more common, as it
may be used on both square and hexagonal bolt heads.
Box wrench openings are offset from the shank by 15
degrees. A box wrench should be used whenever pos-
sible, as it provides the best protection to both the user
and the equipment. The major disadvantage of the box
wrench is that there must be enough clearance above
and around the bolt head to place the wrench over the
bolt head.
The length of the box wrench depends upon the size of
the opening. Some of the more common types of box
wrenches and their uses are shown below and on
page 25-4.
The most common box wrench is the double offset box
wrench. It comes with a different size opening at each
end. The double offset wrench is used to remove normal
nuts and bolts.
25-3
