Great Plains 3PYPA Operator Manual - Manual (Page 121)

Great Plains Manufacturing, Inc. Table of Contents Index Maintenance and Lubrication 117
03/20/2012 Table of Contents Index 401-647M
Marker Maintenance (Option)
See also:
“Initial Marker Setup (Option)” on page 163,
“Marker Operation (Option)” on page 49, and
“Marker Disk Adjustment” on page 61
Marker Shear Bolt Replacement
Refer to Figure 141
If a marker gets caught or hits an obstruction, it is
designed to fail a shear bolt
at the fold, pivot on a sec-
ond bolt , and swing back.
The shear bolt is a hex head cap screw,
7 ⁄
16
-14 x 2in
Grade 5, Great Plains part number 802-589C, plus a
7 ⁄
16
-14 lock nut, Great Plains part number 803-200C.
Install a replacement shear bolt on the vertical faces on
the side opposite from the pivot bolt
. Do not use a
higher grade bolt, or marker hang-ups may result in
machine damage. Do not use a lower grade bolt, or you
may experience nuisance shears.
Refer to Figure 142
If your planting frequently encounters shear hazards, you
can store 6 spare shear bolts/nuts per marker side, in
storage holes
at the fold point.
Marker Chain Length Adjustment
Great Plains suggests checking marker chain slack
every few years. If any maintenance or repairs cause the
chain to be disconnected, correct slack needs to be set
on reinstallation.
Perform any checks and adjustments with the marker
folded and tilted down into its cradle.
Refer to Figure 143
At the mid-point in the exposed chain, pull it toward the
front of the planter.
Measure the distance between that mid-point and the
nearest point on either of the two parallel tubes of the
marker intermediate arm. The target value is:
18 inches (46cm).
If the slack is more than one inch different, remove the
bolt and nut at the lower end of the chain and adjust the
length.
Equipment Damage Risk:
Keep chain slack within range. A chain length too short or too
long can result in marker damage.
Null4:
Figure 141
Marker Shear Bolt
25263
1
2
1
2
2
Null4:
Figure 142
Marker Shear Bolt Storage
25264
1
3
3
3
Null4:
Figure 143
Marker Chain Slack
25266