Torque Wrench Extension Tools; Torque Multiplication - Doosan DX140R Shop Manual

TORQUE WRENCH EXTENSION
TOOLS
Very large diameter, high grade fasteners (nuts, bolts, cap
screws, etc.) require a great deal of turning force to achieve
recommended tightening torque values.
Common problems that could occur as a result are:
• Recommended
capacity of the torque wrench.
• Specialized sockets do not fit the adapter on the front
end (nose) of the torque wrench.
• Generating adequate force on the back end (handle)
of the wrench is difficult or impossible.
• Restricted access or an obstruction may make use of
the torque wrench impossible.
• A unique application requires fabrication of an
adapter or other special extension.
Most standard torque wrenches can be adapted to suit any one
of the proceeding needs or situations, if the right extension tool
is used or fabricated.

Torque Multiplication

A wrench extension tool can be used to increase the tightening
force on a high capacity nut or bolt.
For example, doubling the distance between the bolt and the
back (handle) end of the torque wrench doubles the tightening
force on the bolt. It also halves the indicated reading on the
scale or dial of the torque wrench. To accurately adjust or
convert indicated scale or dial readings, use the following
formula:
I = A x T / A + B where:
I = Indicated force shown on the torque wrench scale or dial.
T = Tightening force applied to the nut or bolt (actual Torque).
A = Length of the torque wrench (between the center of the nut
or bolt and the center of the handle).
B = Length of the extension.
As an example, if a 12" extension is added to a 12" torque
wrench, and the indicated torque on the dial reads "150 ft lb,"
the real force applied to the bolt is 300 ft lb:
A x T
I = =
A + B
NOTE: The formula assumes that there is no added
deflection or "give" in the joint between the extension
Standard Torques
Page 12
torque exceeds the
12 x 300 3600
=
12 + 12 24
measuring
Figure 1
= 150
SP000813