Table of Contents
Advertisement
Auto Rate Control Calibration - Flow Meter
• Perform a self test, choose a high speed and high
rate so that the tank will empty relatively quickly
but make sure the pressure does not exceed 60
PSI.
• When the tank is empty, on the Raven controller
press 'Total Volume' to read what the Raven
flow meter has output to the boom. Record the
reading.
• Check the volume of the tank to see what has
been sprayed out to the boom. Record the
reading.
• Compare the reading from the controller with
the known volume from the tank. If there is a
relatively large discrepancy (i.e. more than 50 litres
out of a 3000 litre tank), the flow meter should
be removed from the sprayer, disassembled and
the condition of the turbine checked and cleaned.
It should be able to spin freely.
Auto Rate Control Calibration - Speed sensors
Raven automatic rate controllers can utilise a speed
reading from:
•
Wheel speed sensor
•
GPS receiver
•
Radar speed sensor
Wheel Speed Sensor
The wheel speed sensor is fitted to the right hand
side wheel of the sprayer and uses four magnets (2
north pole (red) and 2 south pole (black)) fitted
onto the rim to measure speed.
A north and south magnet must pass the sensor
before a pulse is counted. The sensor must be
mounted between 12mm & 19mm from the face of
the magnet to receive a reading. The magnets must
pass directly through the centre of the sensor face.
The speed calibration figure on the console indicates
a measurement of the circumference of the wheel
as it rolls across the ground. The wheel speed sensor
detects when the wheel completes one revolution
and the console calculates the distance the wheel
travels - therefore giving a km/hr reading.
If the ground speed display reading is incorrect
then the calibration and sensor condition must be
checked (see Chapter 11 'Troubleshooting').
18 - Chapter 6 - Calibration
• The flow meter should then be reassembled and
replaced on the sprayer. Perform the volume
check again and if there is still a discrepancy, the
'Meter Cal' value can be changed
i.e. If volume from the controller reads 3100 litres
instead of 3000 litres and the original Meter Cal
value is 185, then:
New 'Meter Cal' value = (185 x 3100) / 3000 = 191
Every sprayer should be calibrated regularly to
ensure minimal error in the application rate. A nozzle
selection chart indicates what application rates
are to be expected. Variations due to nozzle wear,
ground speed error and pressure irregularities can all
add up to result in large application rate errors.
GPS Receiver
If a GPS unit is fitted, GPS ground speed can be
obtained and used in place of the wheel speed
sensor.
To receive a speed reading from the GPS unit a
pulsed niema string must be connected to the
speed cable of the console. The console must then
be set up to accept GPS speed. This is called radar
in the console calibration settings. When using GPS
the console speed cal figure is 200 initially and then
can be fine tuned from this figure. See 'Auto Rate
Control Calibration - Raven SCS450' section for
further information on console setup.
Radar Speed Sensor
The console can also utlise a radar signal for ground
speed reading.
A 't-harness' can be fitted to the tractor radar
harness to send a pulsed signal to the console speed
harness. The console must be setup to receive speed
as "Radar. "
When using a radar the console speed cal figure is
200 initially and then can be fine tuned from this
figure. See 'Auto Rate Control Calibration - Raven
SCS450' section for further information on console
setup.
Prairie 1500-3000L Operator's Manual MY17-MY19 - REV 0
Advertisement
Table of Contents
