TORQUE TOOLS AND TORQUE PRINCIPLES AND PROCEDURES
8-1. General. This chapter discusses the various types
of torque tools available to the aircraft repairer.
8-2. Types of Torque Tools. The torque tools which
are used in the maintenance of Army aircraft is as
a. Manual Torque Tools. Threaded fasteners can be
tightened by the following manual torque tool.
(1) Torque screwdriver. The preset screwdriver,
shown in figure 8-1, is preset to the desired torque. A
device in the tool limits the applied torque to the preset
torque by allowing the handle to turn free of the driven
bit when the preset torque is reached.
(2) Torque Wrenches. Torque wrenches are
divided into three types: deflecting beam, rigid frame
and audible indicating.
(a) Deflecting beam torque wrench. On the
deflecting beam torque wrench shown in figure 8-2, the
deflecting element is the beam itself. When a load is
applied, the beam bends (deflects). A pointer attached
to the socket end remains straight and indicates the
applied load as torque on a graduated plate attached to
the handle end. Other wrenches of this type may have
a graduated dial instead of the indicator plate. Audible
sensory indicators are sometimes provided in addition to
the indicator plate or dial. On the deflecting beam
wrench, the location of the grip on the handle determine
the length of the lever, and the accuracy of the torque
reading. For this reason, some flexible beam wrenches
are provided with a pivoted grip to insure that the point
of load application is maintained at the proper distance
from the socket drive.
Figure 8-1. Preset Torque Screwdriver
(b) Rigid frame torque wrench. The deflecting element
of the' rigid frame torque wrench shown in figure 8-3, is
enclosed in a rigid frame which functions as the lever.
The deflecting element actuates a needle on a
graduated dial that indicates the applied torque.
(c) Audible-indicating torque wrench. The audible-
indicating torque wrench, shown in figure 8-4, has a
micrometer-type barrel for presetting the desired torque.
The deflecting element is a compression spring that
applies pressure to a lever in a detent. When the preset
torque is reached, the lever slips out of the detent with
an audible click which can also be felt in the handle.
b. Power Torque Tools. The two common types of
powered torque tools are the nutrunner and screwdriver.
Figure 8-4. Audible-Indicating Torque Wrench
Figure 8-3. Rigid Frame Torque Wrench
Figure 8-2. Deflecting Beam Torque Wrench