Great Plains 3N-4020 Operator Manual - Manual (Page 70)

66 3N-4010F/3N-4010HDF/3N-4020F Table of Contents Index Great Plains Manufacturing, Inc.
196-359M Table of Contents Index 2013-10-29
Frame-Mounted Coulter Force
Coulter springs are set to 400 lbs (181 kg). In normal
operation at target running depth, the spring is at full
extension. It compresses briefly as obstructions are
encountered.
• In heavy no-till conditions, you may observe the
springs in compression most of the time. This means
that the blades are not reaching the desired coulter
depth. If adequate drill weight is available, you can
increase the spring down-force to compensate.
• In light but rocky conditions, the factory spring setting
may be higher than needed. You can extend blade life
by reducing the force at which the blades ride up over
obstructions.
To adjust the coulter spring:
Refer to Figure 93
1. Raise the drill and install transport locks. See “Lift /
Lower” on page 22.
2. Determine the new spring length desired. See the
table at right.
3. Measure the current length of the spring(s) to be
changed. If already shorter than 9
3 ⁄
4
in (24.8cm), or
longer than 10 1 ⁄
4
in (26cm), do not further adjust
them.
4. Loosen the jam nut .
5. Rotate the adjuster nut until the spring is at the
new length. Tighten the jam nut.
Note: If all springs are continuously in compression, the
coulters can lift the wing frames off the ground (at
the wheels), resulting in uneven coulter depth
and/or uneven seed depth. If high forces are re-
quired, frame weights are probably required.
Row Unit Shut-Off
To shut off seed flow to individual rows, such as to oper-
ate with an alternate row spacing, there are two or three
steps involved:
Refer to Figure 94
1. Block the seed flow to the row with an optional seed
tube plug. See page 121 for ordering.
2. Re-calculate the drill’s swath, and check for any
changes needed to:
• marker extension (see pages 18 and 127) and
• calibration (step 16 on page 43).
3. On 10HD Series, reduce needless wear on the
unused rows by locking them up. See page 80.
Equipment Damage Risk: Do not use spring lengths shorter
than 9.75 in (24.8 cm). It may contribute to premature parts
failure which will not be covered by warranty.
Figure 93
Frame-Mounted Coulter Spring
27139
Spring Length Force at Blade
10.25 in (26.0 cm) 300 lbs (136 kg)
10.00 in (25.4 cm) 400 lbs (181 kg)
9.75 in (24.8 cm) 525 lbs (238 kg)
1
1
2
3
1
2
3
Figure 94
Block Seed Tubes
26279