ratchet assembly, which you can adjust to drive or remove screws.
You can also lock it in position and use it as an ordinary
b. Phillips Screwdrivers. Phillips screwdrivers are used only
for driving Phillips screws (Figure 236). Phillips screws have a
head with two Vslots, which cross at the center. The tip of the
Phillips screwdriver blade is shaped like a pointed or beveled cross
to fit into these slots. This type of screwdriver cannot slip out of
the slot, therefore preventing damage to expensive finishes.
2-7. Holding Tools.
a. Supporting Tools. Supporting tools consist of sawhorses or
trestles used to support workers and materials. Figure 237 shows a
pair of sawhorses, which you might use to support a piece of lumber
that you are cutting.
b. Retaining Tools. Retaining tools consist of various types of
clamps, which fall into the following general categories: C clamp,
doublescrew clamp, and bar clamp (Figure 238).