available as ratchet-types, which allow the screw to be
driven without having to remove the tip from the screw
Ratchet screwdrivers. The ratchet, or spiral,
screwdriver shown in figure 4-16 is fast acting in that it
turns the screw when the handle is pulled back and then
pushed forward. It can be set to turn the screw either
clockwise or counterclockwise, or it can be locked in
position and used as a standard screwdriver. The
ratchet screwdriver is not a heavy-duty tool and should
be used only for light work.
Figure 4-16. Ratchet Screwdrivers
screwdriver, extreme care must be used
prevent the blade from slipping out from
the slot in the screw head. If this occurs,
the surrounding structure is subject to
Nonmagnetic screwdriver. The nonmagnetic
screwdriver is shaped like a common screwdriver, but
the blade is made of brass so as to have no magnetic
effect. It is used for compensating compasses.
Safety. The following precautions must be kept
in mind when using screwdrivers:
Ensure that the handle of the screwdriver
Do not use a screwdriver for prying,
punching, chiseling, scoring, or scraping.
Do not use a screwdriver to check an
electric circuit since an electric arc will
burn the tip and make it useless. In some
cases, an electric arc may fuse the blade
to the unit being checked.
When using a screwdriver on a small
part, always hold the part in the vise or
rest it on a workbench. Do not hold the
part in the hand, because the screwdriver
may slip and cause serious personal
Use The following paragraphs describe the use
of various types of screwdrivers.
Proper fit. Select a screwdriver large enough so
the blade fits closely in the screw slot. A loose fitting
blade can slip and cause burring of the screw slot and
damage to the blade. Proper and improper fits are
shown in figure 4-17. It is important that the screwdriver
be held firmly against the screw to prevent it from
slipping and possibly injuring the mechanic or scarring
Use of screwdriver. A screwdriver is used as
Insert the screwdriver tip into the screw
slot of the screw.
Turn the screw as required. Keep the
screwdriver in line with the screw.
Use of offset screwdriver. The procedure for
using an offset screwdriver is as follows (see figure 4-
Figure 4-17. Proper Fit of Screwdrivers