Great Plains NTA3007HD Operator Manual - Manual (Page 81)

Adjustments 77
04/04/2011 166-207M
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.
Refer to the seed rate charts and set each variable rate
gearbox control arm to its scale setting for the desired
seeding rate.
To adjust the Variable Rate Gearbox for each hopper:
Refer to Figure 82
1.
Remove the hairpin cotter securing the gearbox
adjustment crank.
2. 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.
3. Reinsert the hairpin cotter.
Note: The variable rate gearbox operates optimally be-
tween 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 de-
grees 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 en-
try 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.
Null4:
Figure 82
Variable Rate Gearboxes
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