Great Plains 3N-4025P Operator Manual - Manual (Page 120)

116 3N-40P Table of Contents Index Great Plains Manufacturing, Inc.
196-538M Table of Contents Index 2014-01-29
25 Series Row Unit Down-Pressure
Refer to Figure 163
Row unit springs
provide the primary down pressure
necessary for row unit disks to open a seed trench. The
weight of the row units themselves contributes about 145
pounds (66 kg) of the total force.
The springs allow the row units to float down into
depressions and up over obstructions. Springs also
provide down force on coulters when using optional row
mounted coulters, and provide the primary down force on
row cleaners (optional), seed firmers (optional) and
press wheels.
An adjuster cam sets down pressure individually for
each row unit. This is useful for penetrating hard soil and
planting in tire tracks. For best results always adjust
tractor tires so they are not ahead of 30 inch rows.
Refer to Figure 165
Use only enough down pressure to cut the seed trench
and maintain proper soil-firming over seed. Excessive
row unit down force will lead to premature wear on row
unit components, uneven seed depth and gauge wheel
slippage.
Refer to Figure 164 (shown at cam setting 1),
Figure 165 and Figure 166
To adjust down pressure, use a 1
1 ⁄
8
inch (29 mm) open
end wrench or the tool stored under the walkboard.
1. Raise the drill. Although this adjustment can be
made with the drill lowered, the springs will be in
tension, and will require more effort. The extra force
required may also damage tools.
2. Install lift cylinder locks.
3. Put tractor in Park and shut it off.
4. Position wrench on the fixed nut near or slightly
forward of vertical.
Cam Notch Pounds Kilograms
zero (out of notch) Maintenance Only
one 345 156
two 370 168
three 400 181
four 450 204
five 500 228
six 550 249
tip Do Not Use
Figure 163: 25 Series:
Row Unit Springs
25118
2
1
1
Figure 164
25 Series Row Unit
Spring Adjustment
25268
2
3
5
4
6
2
Figure 165
Row Unit Minimum Cam (1)
27065
3
4