the amount of force required to deflect a cable a
certain distance at right angles to its axis. The cable
to be tested is placed under the two blocks on the
instrument, and the lever assembly on the side of the
instrument is pulled down. Movement of this lever
pushes up on the center block, called a “riser.” The
riser pushes the cable at right angles to the two
clamping points.
The force required to do this is
indicated by a pointer on the dial. Different risers are
used with different size cables. Each riser carries an
identifying number, and is easily inserted in the
instrument.
Each tensiometer is supplied with a calibration
table to convert the dial readings into pounds. One of
these calibration tables is shown in figure 9-23. For
example, if the pointer on the dial indicates 48 with a
No. 2 riser and a 3/16-inch diameter cable, the actual
tension on the cable is 100 pounds. With this
particular instrument, the No. 1 riser is used with
1/16-, 3/32-, and 1/8-inch diameter cables.
CAUTION
The calibration table applies to the
particular instrument only, and cannot be
used with any other. For this reason, the
calibration table is secured inside the cover
of the box in which the instrument is kept.
The chart is serialized with the same serial
number as the instrument. Using the cali-
bration table from another instrument will
result in inaccurate reading.
During the adjustment of turnbuckles, the
calibration table must be used to obtain the desired
tension in a cable. For example, to obtain a tension of
110 pounds in a 3/16-inch diameter cable, the No. 2
riser is inserted in the instrument and the number
opposite 110 pounds is read from the calibration table.
In this case, the number is 52. The turnbuckle is
then adjusted until the pointer indicates 52 on
dial.
NOTE: Tensiometer readings should not be
taken within 6 inches of any turnbuckle, end
fitting, or quick disconnect.
the
In some cases, the position of the tensiometer on
the cable may be such that the face of the dial cannot
be seen by the operator. In such cases, after the lever
has been set and the pointer moved on the dial, the
Figure 9-24.—Rigging pin set.
9-30
