SAM 400 SPEED-AREA-DISTANCE METER
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The display will show 'Auto' for 2 seconds,
and then show the number of received
pulses.
3. Drive the vehicle until the chosen reference
point on the tractor/implement is opposite
the second marker.
The instrument counts and displays the
sensor pulses received over the distance
travelled.
4. Press the CAL button to end the autocal.
The new factor is then displayed.
Manually calculating the Factor
The smaller the speed sensor factor the better the speed update will be. Aim
for a factor less than 2.000 m (78.78").
NOTE: Perform the following calculations in inches or metres depending on whether
the instrument is set for Imperial or Metric units. If you calculate the factor
using any other unit of measurement e.g. feet or centimetres, the forward
speed display will be incorrect.
(i) If a single magnet is installed (as with a standard RDS Propshaft Sensor
kit), the distance travelled for each turn of the prop shaft must be
determined. To determine this distance, drive the vehicle forwards for exactly
10 revolutions of the prop shaft. Measure this distance (in inches or metres)
and divide by 10, to find the Speed Sensor Factor.
(ii) If 2 magnets are installed (as with a standard RDS Wheel Sensor kit), the
distance is 1/2 the effective rolling circumference of the wheel. To determine
this circumference, drive the vehicle forward in field conditions (with the
implement attached if applicable), for exactly 10 revolutions of the sensed
wheel. Measure this distance (in inches or metres) and divide by 20 to find
the Speed Sensor Factor.
(iii) If 4 wheel magnets are installed, the distance is 1/4 the effective rolling
circumference of the wheel. To determine this circumference, drive the
vehicle forward in field conditions (with the implement attached if applicable),
for exactly 10 revolutions of the sensed wheel. Measure this distance
(metres) and divide by 40 to find the Speed Sensor Factor.
Carry out this test whenever soil conditions or wheel sizes change.
(iv) If an RDS Radar sensor is installed, the Speed Sensor Factor is 0.008 m (or
0.312 inches).
If the calibration factor works out at over 2.000 m (78.78 inches), consider
fitting additional magnets. Extra magnets are recommended if the vehicle has
large diameter wheels or is slow-moving. In extreme circumstances you can
find that the speed keeps going to zero as it times out before the next pulse
arrives.
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