micro-trak FLOWTRAK II, Reference Manual

Page: 21 / 44

21
Illustration 12
To determine SPEED CAL, measure the distance of one
complete wheel revolution and divide by the number of
magnets installed.
For the console to calculate the correct speed and measure
distance accurately, the circumference of the sensor-equipped
wheel must be entered. Determine the circumference of the
sensor-mounted wheel to the nearest tenth of an inch (tenth
of a centimeter) with the fol low ing method:
METHOD:
Mark the tire with a piece of chalk and mea-
sure the distance traveled on the ground for one com plete
rev o lu tion. See Illustration 12. For improved accuracy, it
is recommended that you perform this function in field
conditions, measure several revolutions, and take the
average.
Divide the measured revolution by the number of magnets
installed to get your starting SPEED CAL calibration value.
Once calibration of the system is complete, this number
should be fine-tuned for optimum accuracy.
For fine-tuning the SPEED CAL value, see page 22.
Drive Shaft Speed Sensor Calibration
NOTE: If you have mounted the magnetic speed sen sor on
a wheel, skip this step and go on to Fine Tuning Speed/
Distance Calibration Values.
Because of the difference in wheel-to-drive shaft ra tios, it is
difficult to determine a calibration value for installation on
a drive shaft by measuring a wheel. You must start with an
estimated calibration value and then fine-tune the cal i bra tion.
Any number between 10 and 15 (255 mm to 380 mm) is a
good starting value.
NOTE: For fine-tuning the SPEED CAL value, see next
section.
Calibration
(cont)
Determining the Speed Cal
(Skip this section if using radar or GPS speed sensor)