Figure 8-20. Angle Extension Torque
c. Never drop a torque tool on the floor. If this does
happen, the wrench should be checked for accuracy
before its use.
d. Do not file, mark, or etch the beam of a flexible
beam wrench. This structure is the measuring element
of the wrench. Any alteration will seriously affect the
accuracy of the wrench.
e. Do not load a tool in excess of its capacity.
Overloading a torque tool can result in permanently
deforming the torque-sensing element and damaging
f. Before use, check all nonadjusting torque wrenches
for minimum torque indication. If they do not indicate
minimum torque, tag them for calibration.
8-7. Testing of Torque Tools . A torque wrench is
subject to wear and other factors which can be
detrimental to the accuracy of the tool. Periodic testing
in accordance with applicable directives is essential to
ensure continued accuracy. Several different types of
torque wrench testers are manufactured and, to ensure
their proper use, some understanding of their operating
principles is desirable.
a. Description. A torque wrench tester consists of a
force resisting element to absorb the load applied by the
tool and a dial or scale to indicate the magnitude of the
applied load in torque units. A maximum reading
pointer is provided that remains at the point of
maximum applied torque and holds the reading when
the load is released until reset to zero by the operator.
b. Indication. The force resisting element may be a
weight, a steel spring, a torsion bar, or strain gauge load
cells. The movement of deflection of the force resisting
element resulting from the application of the load
applied by a torque wrench is relatively small and must
be magnified in order to indicate the small variations in
the amount of the applied load. Magnification is
accomplished on mechanical-type tester by a gear
segment and pinion or a mechanical linkage. Other
of testers use optical magnification or electronic
8-8. Repair and Calibration. The repair and
calibration of torque tools is normally the responsibility
of the Area TMDE Support Team (ASTS) (TMDE is
Test, Measurement, and Diagnostic Equipment). TB
750-111 contains the procedures for repair and
calibration of torque wrenches for local units.
8-9. Torque Multipliers . The direct application of
torque to a fastener is limited by the force that can be
applied and by the length of the wrench. The force
varies to some extent but is approximately 100 pounds.
With a wrench 30 inches long, the torque that can be
applied is 100 x 30 or 3000 inch-pounds (250 foot-
pounds). Higher torque values are possible with longer
wrenches; however, there is a limit to the size of a
wrench that can be used effectively by one man.
Torque multipliers are used for the high torque values,
such as those specified
Figure 8-19. Improper Application of Force