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(4) If the stroboscope flashes N times the speed of the moving object, N
images will be seen.
(5) The stroboscope has a built-in calibration system using the line
frequency as the standard.
A vibrating reed, oscillating at twice the line
frequency, is mounted near the flasher tube so that its end can be viewed during
the calibration procedure. A pair of calibration potentiometers (one for the high
end and one for the low end of the dial) act as oscillator trimmers and correct for
dial errors. With the dial set at a point that is a multiple or submultiple of the
line frequency, the prescribed potentiometer is adjusted until the reed appears to
stop. This adjustment is made at points near both the high and the low end of the
dial.
(6) The stroboscope can also be used for the observation of equipment in
motion.
Moving equipment can be studied in either the "stopped" state or in
apparent motion.
(7) This ends the discussion of tachometers and stroboscopes.
Now turn
your attention to a type of rotational measurement in which you measure rotational
force (torque) instead of speed or frequency.
A study of the proving ring as a
vertical force (torque) measurement device is included.
6.
Torque Measurements.
When your laboratory supports missile or special type
aircraft installations, you use torque calibrators to calibrate or adjust torque
wrenches and handles. Your ability to calibrate the torque devices. This section
includes a brief discussion on torque wrenches and handles to include the Sweeney
and Baldwin type torque wrench calibrators.
In addition, this section explains
some of the principles applied when proving rings are used for torque measurements.
a. Torque Wrenches and Handles.
Maintenance and repair shops stock torque
wrenches of all sizes.
The purpose of these wrenches is expressed in two
paragraphs taken from two different torque wrench (handle) publications. The title
of each paragraph is "Purpose." The paragraphs are as follows:
The purpose of these wrenches is to apply an adjustable, predetermined,
torque-limiting force to bolts, nuts, and other threaded parts.
The torque handle described in this technical manual is designed to limit
the torque applied to fastening components (nuts, bolts, screws, etc.), the limit
being adjustable, in graduated increments by the operator.
b. Although the paragraphs in the preceding list were taken from two
different publications, you can see that both include the function of limiting
torque applied to nuts and bolts by specific amounts.
c. Compare the operating procedures for two typical torque devices to help
you understand how the devices are operated. In the first operating procedure you
make the following preliminary adjustments.
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