Great Plains YP825A Operator Manual - Manual (Page 109)

Great Plains Manufacturing, Inc. Table of Contents Index Maintenance and Lubrication 105
2014-08-15 Table of Contents Index 401-651M
Re-Phasing Lift System
In typical use during a single planting operation, it is
normal for the lift cylinders to get out of phase, resulting
in uneven raising and lowering of the planter.
Every 8- to 10 passes, re-phase the cylinders with this
procedure:
Raise the planter completely, and hold the hydraulic lever
or switch in Retract for several seconds after the planter
reaches full elevation, or until all cylinders are fully
retracted.
When all cylinders are fully retracted, momentarily
reverse (Extend) the control to lower the planter 12mm
(
1 ⁄
2
in).
Lift Cylinder Bleeding
Normally the lift hydraulics are bled at the factory before
shipping, and bleeding should not be required other than
to raise fully and hold lever on for one minute or until all
cylinders extend fully.
Refer to Figure 118
If it is necessary to further bleed lift system, follow these
steps.
1. Consult lift circuit hydraulic diagram on page 142
(repeated at right in smaller scale)
2. Check that tractor hydraulic reservoir is full. Set
hydraulics for low flow rate.
3. Lower planter.
4. Loosen the JIC fittings at the rod ends (bottom) of
the three left lift cylinders. Leave the right
undisturbed.
5. Extend the lift circuit until fluid appears at each the
loosened fittings. As fluid appears, set control lever
to neutral and secure each fitting.
6. Retract the circuit. Set control lever to neutral.
7. Extend the lift circuit until both cylinders are fully
extended.
8. Loosen the JIC fitting at the base (top) ends of the
three right lift cylinders. Leave the left undisturbed.
9. Retract the circuit until fluid appears at each
loosened fitting. As it appears, set control lever to
neutral and secure each fitting.
10. Set circuit control to neutral and secure fitting.
11. Unless it is suspected that a large amount of air is in
the line between the cylinders, rely on the normal
re-phasing operation to purge it. Otherwise...
12. Loosen the JIC fitting at the base (top) end of the left
cylinder .
13. Retract lift circuit until fluid appears.
14. Set circuit to neutral and secure fitting.
15. Extend and retract circuit several times.
Figure 118
Bleeding Lift System
25463
1
2
3
1
1
2
2
1
2
3