Figure 2-2. Measuring belt speed on a sanding machine, using Type 1531 Strobotac ond Type 1531-P3 Linear Speed Wheel.

Figure 2-2. Measuring belt speed on a sanding machine, using Type

1531 Strobotac ond Type 1531-P3 Linear Speed Wheel.

stroboscope is then adjusted to produce the proper stationary image. The

linear speed of the moving object is determined from the stroboscope

dial reading.

The range of surface speeda that can be measured with the large

wheel is 50 to 12,500 FPM (feet per minute); with the small wheel the

range is 10 to 2500 FPM. Press the appropriate wheel against the

moving surface just firmly enough to prevent any slipping.

The large wheel is suitable for the measurement of relatively high

linear speeds, It has a circumference of 0.5 foot and is marked "SINGLE

IMAGE, FPM = RPM 2". Adjust the stroboscope dial to the highest set-

ing that produces a single stationary image. (NOTE: To check the dial

setting, switch the stroboscope to the next higher range. If the original

setting was correct, six images will now be produced.) The linear speed

of the moving surface in feet per minute is the stroboscope dial reading

divided by 2.

The small wheel, suitable for the measurement of relatively slow

linear speeds, has a circumference of 0.2 foot and is marked "2 IMAGES,

RPM 10". Adjust the stroboscope dial so that a double stationary image

is obtained. The image will appear as a full-diameter line on the wheel,

(NOTE: To check the dial setting, turn the stroboscope dial to half of its

double -image value. If the original setting was correct, a single image

will now be produced.) The linear speed of the moving surface in feet

per minute is the stroboscope dial reading divided by 10.