TYPES AND USES - Continued
TORQUE WRENCHES (Cont)
A scale torque wrench has a rod which runs parallel to
the handle and the drive element. This rod moves
across the scale to the right or left as torque is applied.
POWER TORQUE WRENCH
Using a powerful gear train, the power torque wrench
is completely mechanical in operation. The power
torque wrench is operated by a hand crank. The
torque is calibrated in foot pounds, which is shown
by a dial indicator on the top face of the power
torque wrench. This type of torque wrench is used for
tightening nuts and bolts requiring 200 or more foot
pounds of torque.
A special feature of this type of torque
wrench is that it is possible to loosen as
well as tighten nuts and bolts.
Two basic types of spanner wrenches are the hook-type
and the pin-type. Hook-type spanner wrenches are
either fixed or adjustable and are normally used to
tighten fire hoses or similar couplings which have a
protruding lip. Pin-type spanner wrenches have pins
protruding from the handle which fit into holes in the
coupling or plate to be tightened or loosened. Spanner
wrenches are special purpose wrenches and are to be
used only for their intended purpose.
HOSE COUPLING PIN
Three kinds of hook-type wrenches include the hose
coupling pin, for tightening and loosening hose coupl-
ings, the fixed hook, for tightening or loosening coupl-
ings with protruding rims or edges, and the adjustable
The adjustable hook-type is similar to the fixed hook-
type. However, it may be adjusted around objects and
fastened before use.