Great Plains 2SNG30 Material Rate - Manual (Page 22)

20 2SNG24 & 2SNG30 Great Plains Manufacturing, Inc.
202-578B 12/01/2010
Native Grass Calibration Formulas/Example
Formulas Example
Know your Desired seed rate in pounds per acre For this example:
32
Weigh the empty sample container(s) For this example, three 1.5# buckets:
4.5 pounds
Note the current Drive Type and Native Grass sprocket pair in use. For this example, a model 2SNG30
currently set to:
Drive Type 1
NG Driving: 19T
NG Driven: 15T
Operate crank/gauge wheel for one acre From the table on page 18:
245 revolutions
Weigh the collected seed plus container(s) In this example:
7.0 pounds
Calculate the sampled rate at each seed cup. Assuming 3 cups sampled.
Calculate the sampled rate for all rows working: For this example, from the table on
page 18, a 48-row 7.5in 2SNG30:
In the chart on page 22, find the Cup Revolutions Per Acre for the tested
configuration. The table cell at Drive Type 1
19T Driving, 15T Driven is:
155.17
Calculate the Sampled pounds per cup revolution This is essentially a correction factor:
Calculate the Target cup revolutions per acre Our Target Cup Rate:
In the chart on page 22, find the table cell with the value closest to the
Target. Use the Drive Type and Sprocket shown for that cell. In this case,
there are four different configurations with cup rates close to 124.1. The
closest is 125.7. The drive configuration for that target:
Cell: 125.7
Drive Type: 1A
Driving: 15T
Driven: 30T
MeasuredSeed WeightOfEmptyContainer –
3
------------------------------------------------------------------------------------------------------------------- SampledPoundsPerSeedCu =
7.0 4.5 –
3
-------------------- 0.83 =
oundsPerSeedCup NumberOfOpeners × SampledPoundsPerAc =
0.83 48 × 40.0 =
SampledPoundsPerAcre
CupRevolutionsPerAcre
------------------------------------------------------------------- SampledPoundsPerCupRevolution =
40.0
155.17
----------------- 0.258 =
DesiredSeedRate
SampledPoundsPerCupRevolution
----------------------------------------------------------------------------------------------- T etCupRevolutionsPerAcre arg =
32
0.258
------------- 124.1 =