Slide back the lock ring to the UNLOCK position.
Set the desired torque value by rotating the index on the handle to the
value on the calibrated barrel.
Slide the lockring up to the LOCK position. (The groove or index on the
handle lines up with the groove on the barrel.)
d. After the preliminary adjustments are complete, the torque wrench then
operates like an ordinary wrench until the torque limit is reached. A breakthrough
occurs which allows the wrench to move freely and sharply before reaching a
positive stop. A release of the wrenching pressure automatically resets the torque
wrench and it is ready for the next operation.
The torquing force should be
applied in a smooth, steady motion. The natural tendency is to, overtorque, with
resultant damage to the fastener or the torque wrench. The torque wrench operator
should proceed carefully until he is able to anticipate the breakthrough action.
cycles. This action permits the internal mechanism to redistribute a thin film of
lubricant throughout the working parts.
You may have to perform this operation
when wrenches are brought to the laboratory. When changing the handle setting to
the lowest reading on the scale, be extremely careful after reaching the lowest
increment reading to avoid shearing the stop pins inside the handhold by further
turning in this direction.
The pins are designed as a resistant point to enable
you to determine when you have reached the low handle setting.
These pins, when
sheared, allow the handle to disengage from the body and give an erratic torque
f. If the preceding procedure was familiar, you are learning about torque
wrench operation. Examine the second procedure so that you can compare the two.
g. When you wish to set the torque handle to the selected value, unlock the
grip and adjust the handle to the desired setting on the micrometer type scale;
then relock the grip and install an attachment on the square drive of the handle.
Apply the handle assembly to the fastener to be torqued and pull the handle in a
clockwise direction with a smooth and steady motion.
A fast or jerky motion
results in an improperly torqued fastener.
When the torque applied reaches the
predetermined torque setting of the handle, the handle automatically releases or
"breaks," producing approximately 150 to 200 free travel. The release is distinct,
is easily detected by the mechanic, and is an indication of completed torquing
action on the fastener.
h. In many torquing applications it is necessary to use various accessories
other than those that operate coaxially with, and are attachable to, the square
drive of the torque handle, i.e., common sockets, screwdriver attachments, and
internal wrenching adapters. Any extension or adapter