Sockets are classified by size according to two
factors. One is the size of the square opening, which
fits on the square drive lug of the handle. This size is
known as the drive size. The other is the size of the
opening in the opposite end, which fits the nut or bolt.
The standard toolbox can be outfitted with sockets
having 1/4-, 3/8-, and 1/2-inch-square drive lugs.
Larger sets are usually available in the tool room for
temporary checkout. The openings that fit onto the
bolt or nut are usually graduated in 1/16-inch sizes.
Sockets are also made in deep lengths to fit over
spark plugs and long bolt ends.
There are four types of handles used with these
sockets. (See fig. 1-8.) Each type has special
advantages, and the experienced worker chooses the
one best suited for the job at hand. The square
driving lug on the socket wrench handles has a
spring-loaded ball that fits into a recess in the socket
receptacle. This mated ball-recess feature keeps the
socket engaged with the drive lug during normal
A slight pull on the socket, however,
disassembles the connection.
RATCHET. The ratchet handle has a reversing
lever that operates a pawl (or dog) inside the head of
the tool. Pulling the handle in one direction causes
the pawl to engage the ratchet teeth and turn the
socket. Moving the handle in the opposite direction
causes the pawl to slide over the teeth, permitting the
handle to back up without moving the socket. This
allows rapid turning of the nut or bolt after each
partial turn of the handle. With the reversing lever in
one position, the handle can be used for tightening.
In the other position, it can be used for loosening.
HINGED HANDLE. The hinged handle is also
very convenient. To loosen tight nuts, swing the
handle at right angles to the socket. This gives the
greatest possible leverage. After loosening the nut to
the point where it turns easily, move the handle into
the vertical position and then turn the handle with the
SLIDING T-BAR HANDLE. When you are
using the sliding bar or T-handle, the head can be
positioned anywhere along the sliding bar. Select the
position that is needed for the job at hand.
SPEED HANDLE. The speed handle is worked
like the woodworkers brace. After the nuts are first
loosened with the sliding bar handle or the ratchet
handle, the speed handle can be used to remove the
nuts more quickly.
In many instances the speed
handle is not strong enough to be used for breaking
loose or tightening the nut. The speed socket wrench
should be used carefully to avoid damaging the nut
Several accessory items complete the socket
wrench set. Extension bars of different lengths are
made to extend the distance from the socket to the
handle. A universal joint allows the nut to be turned
with the wrench handle at an angle. Universal sockets
are also available. The use of universal joints, bar
extensions, and universal sockets in combination with
appropriate handles makes it possible to form a
variety of tools that will reach otherwise inaccessible
nuts and bolts.
Another accessory item is an adapter, which
allows you to use a handle having one size of drive
and a socket having a different size drive.
example, a 3/8- by 1/4-inch adapter makes it possible
to turn all 1/4-inch-square drive sockets with any
3/8-inch-square drive handle.
There are times when, for engineering reasons, a
definite force must be applied to a nut or bolt head.
In such cases a torque wrench must be used. For
example, equal force must be applied to all the head
bolts of an engine. Otherwise, one bolt may bear the
brunt of the force of internal combustion and
ultimately cause engine failure.
The three most commonly used torque wrenches
are the deflecting beam, dial indicating, and
micrometer setting types (fig. 1-10). When using the
deflecting beam and the dial indicating torque
wrenches, read the torque visually on a dial or scale
mounted on the handle of the wrench.
To use the micrometer setting type, unlock the
grip and adjust the handle to the desired setting on the
micrometer-type scale, then relock the grip. Install
the required socket or adapter to the square drive of
the handle. Place the wrench assembly on the nut or
bolt and pull in a clockwise direction with a smooth,