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Engineman 2 - Intermediate engine mechanics training manual | Next
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of threaded fasteners. Figure 2-l1 shows three types of
torque wrenches.
To use a torque wrench, first select the proper torque
value for the torquing procedure you are using. Next,
Figure 2-10.—A typical stroboscope.
Figure 2-11.—Typical torque wrenches.
select the torque wrench with the correct capacity. The
torque value should be in the second or third quarter of
the wrench’s torque scale because the first and last
quarters of the scale are not as accurate as the middle
quarters.
Torque wrenches are precision tools. Handle them
with care and always follow the manufacturer’s manual
when you use them.
TORQUE MULTIPLIER
Torque multipliers are geared devices attached to
the torque wrench to increase the force of torque. The
most preferred ratio of the torque multiplier is 4 to 1. To
use a torque multiplier, select one with an output
capacity above the required torque. Be sure to follow the
manufacturer’s operating manual to avoid personnel
injury and damage to the equipment.
TORQUE ADAPTERS
Torque adapters allow the torque wrench to be used
to tighten parts and fasteners other than standard nuts
and bolts. Adapters are available in a variety of shapes
geared to the repair of different parts of the diesel
engine. Several types of torque adapters are shown in
figure 2-12.
When you use an extension adapter, the torque
applied to the part or fastener will be greater than the
torque indicated on the torque wrench. Therefore, you
must account for the length of the adapter to apply the
proper torque to the part or fastener. Figure 2-13
illustrates the points of measurement.
The torque applied by the adapter is directly related
to the length of the adapter. As the length of the adapter
increases, so does the applied torque.
To determine the actual torque applied to the part or
fastener, assume that the length of the torque wrench is
L and the length of the adapter is A. Assume also that
Tw is the torque indicated on the scale of the torque
wrench and Ta is the torque exerted at the end of the
adapter.
To determine Ta, simply multiply the torque
indicated on the torque wrench (Tw) by the ratio of the
total effective length of the assembly (L + A) to the
length of the torque wrench (L).
or
2-7
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