Great Plains PD8070 Operator Manual - Manual (Page 43)

Great Plains Manufacturing, Inc. Table of Contents Index Adjustments 39
2014-07-23 Table of Contents Index 401-479M
Contact Drive Tension
Refer to Figure 35 and Figure 36
Occasionally, due to planting height or planting
conditions, it may be necessary to adjust the spring
tension to keep the contact drive tire from slipping. For
example, if you experience low seeding rates in wet
conditions, it may be possible to compensate for this by
increasing contact drive tension, by tightening 4 bolts
(2 on each contact drive).
This is only effective if the ground drive wheels are not
themselves slipping excessively. The correct solution
may be to wait for drier planting conditions.
1. Raise planter to ease adjustment.
2. Check existing cast nut position on all 4 bolts. The
factory setting, measured from the bottom
circumference of the cross bar
to the top of the
cast hex nut (not to the top of the jam nut) is:
25 mm and 32 mm (1 inch to 1
1 ⁄
4
inch)
If the casting position is greater than this, return it to
factory setting and recheck field operation before
making further adjustments.
3. Loosen jam nuts .
4. Turn bolts clockwise to increase contact drive
tension. The change in contact tension, per
revolution of the pair of bolt heads, is approximately:
3.3 kg/turn (7.3 pounds/turn)
5. Recheck population (page 32) after adjusting.
Note: Do not use increased tension with under-inflated or
worn tires. The effective rolling radius of such tires
is reduced (increasing planting rate), and additional
contact drive tension cannot compensate for it.
Adjust tension until contact drive tire has enough tension
to stay in contact with gauge wheel.
Note: DO NOT increase tension so much that contact
drive tire resists turning.
Figure 35
Contact Drive Springs
25467
3
2
4
1
1
2
3
4
Figure 36
Contact Drive Tension
28134
4
1
4