Great Plains NTA3007 Operator Manual - Manual (Page 93)

Great Plains Manufacturing, Inc. Table of Contents Index Adjustments 89
2012-07-02 Table of Contents Index 166-371M
Setting Variable Rate Gearbox
The variable rate gearbox lets you infinitely vary meter
drive speed to attain a wide range of seeding rates. The
ratio of gearbox input speed to output speed is controlled
by the position of a gearbox control arm. The control arm
has an indicator that points to a scale marked in degrees.
The Seed Rate and Fertilizer Rate charts show the rate
for each degree of the control arm rotation.
• Manual: On the standard NTA907 or NTA3007 drill, the
control arm is manually positioned with a crank .
The initial setting is based on the seed rate chart, and
refined via calibration.
• Servo: With the optional Variable Rate Kit, the control
arm is positioned by a linear actuator (not shown). The
setting is commanded by the seed monitor, based on
the rate entered on the seed monitor console, and the
current Calibration Constant. The initial “Cal. Const.” is
found in the seed rate chart, and refined via
calibration.
Refer to Figure 90
Manual Rate Setting
1.
Consult the seed rate chart for your crop, flute stars
and rate Range. Note the gearbox setting.
2. Remove the hairpin cotter securing the gearbox
adjustment crank.
3. Rotate crank until the control arm indicator points to
the scale setting that matches the rate from the seed
rate chart or determined by calibration.
4. Re-insert the hairpin cotterr.
Variable Rate (Servo) Rate Setting
1.
Consult the seed rate chart for your crop, flute stars
and rate Range. Note the “Cal. Const.”
2. Enter the chart Calibration Constant on the seed
monitor (for the Channel associated with the hopper
and gearbox). If you have calibrated this seed, use
the recorded Cal. Const. developed from that
calibration.
3. Enter the desired material rate on the seed monitor
(for the Channel associated with the hopper and
gearbox).
Note: The variable rate gearbox operates optimally
between 30 and 70. If a seed has charts for both
HIGH Range and LOW Range, the most
consistent results are obtained when the gearbox
control arm is set between 30 and 70. Settings
below 20 degrees are not recommended. When
the control arm is set above 70 degrees, large
movements of the arm result in small changes in
seeding rate.
Note: If you will be metering the same material from both
bins at the same time, use the seed rate chart
entry for half the desired application rate. Do not
use a half scale setting - the effect of the variable
rate gearbox control arm is not linear.
Note: The hand crank is present on both manual drills,
and (servo) drills with the Variable Rate kit. On
servo drills, the crank is disconnected from the
control arm. To revert to manual control, move the
coupler pin from the servo control arm to the
manual control arm.
Figure 90
Variable Rate Gearboxes
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