(b) Box end wrenches. Box wrenches (fig 5) are so named because they
completely surround or box the bolthead or nut. The opening in a box wrench
contains 6 or 12 notches, called points, arranged in a circle. The box wrench is a
safer tool than the open end wrench since it will not slip off the work. As little
as one-twelfth of a turn can be taken at each stroke, if necessary, in close
quarters. Box wrenches may have straight handles, they may be offset, or the box
end may be offset. Box wrenches are available in the same sizes as are open end
wrenches and usually have two openings: one opening, 1/16 inch larger than the
other. Some openings may be 1/32 or 1/8 inch larger than the other. A ratchet box
wrench usually has two 12-point openings and is not automatically reversible.
However, it can be turned around to do both tightening and loosening operations.
Being of sturdy, thin construction, they are convenient for working in limited
spaces. Ratchet box wrenches are issued in four sizes ranging from 3/8 and 7/16-
inch openings to 3/4 and 7/8-inch openings.
Box and combination wrenches.
(c) Combination open and box wrenches. Combination wrenches (fig 5)
have one open end and a box wrench at the other end. Combination wrenches may be
made with any combination of sizes, offsets, and angles as discussed above.
(d) Socket wrenches. The common socket wrench is boxlike and made as a
detachable socket (fig 6) for various types of handles. A socket wrench set
usually consists of various sized sockets, a ratchet (fig 7), sliding bar tee,
speeder, speed tee, ratchet adapter, nut spinner, 3/8-inch drive handle, and
extensions. Socket wrenches have two openings: one a square hole which fits the
handles and the other a circular hole with notched sides to fit the bolt or screw
head or nut to be turned. The square hole is made 1/4, 3/8, 1/2, 3/4, or 1 inch in
diameter; each must be driven with the matching drive or speeder handle. The
notched opening may have 6, 8, or 12 points. Socket wrenches are the fastest
wrenches to use, since the ratchet handle permits the socket to remain on the nut
or bolt and the handle does not have to be removed from the socket for turning.
Socket wrenches are sized from 5/32 to 3-1/8 inches in steps of 32ds, 16ths, or
8ths of an inch.