Great Plains 148-152P Assembly Instructions - Manual (Page 4)

5/5/2009
Great Plains Mfg., Inc.
Dual Marker Option 4
Bleeding the Hydraulic System
!
CAUTION!
Escaping fluid under pressure can have sufficient force to pen-
etrate the skin. Check all hydrualic lines and hoses before ap-
plying pressure. Fluid escaping from a very small hole can be
almost invisible. Use paper or cardboard, not body parts, to
check for suspected leaks. If injured, seek medical assistance
from a doctor that is familiar with this type of injury. Foreign
fluids in the tissue must be surgically removed within a few
hours or gangrene will result.
NOTE: JIC fittings do not require high torque. JIC
and o-ring fittings do not require sealant. Always use
liquid pipe sealant when adding or replacing pipe
thread fittings. To avoid possible danger of cracking
hydraulic fittings from overtightening - DO NOT use
plastic sealant tape.
NOTE: Check the hydraulic fluid level in the tractor
reservoir and fill to the proper level before starting
procedure. Add fluid to the system as needed. A low
reservoir level may draw air back into the system,
and can cause jerky or uneven cylinder movements.
!
DANGER!
Keep all persons clear.
NOTE: The following instructions must be followed
to bleed the markers hydraulic system. The markers
must be properly bled to displace air in the hydraulic
system and for the sequence valve to work properly.
Failure bleed the hydraulic system could cause the
marker to drop quickly to the ground causing dam-
age to the marker and voiding the warranty.
Refer to Figure 5
1.
Markers should be manually folded into transport po-
sition when charging the hydraulic system for the first
time. Remove cylinder pin securing rod end of each
cylinder to marker link arms. Swing link arm up and
out of the way.
2. Connect hoses to tractor’s remote hydraulic outlets.
3. Loosen hydraulic hose fittings at rod end of marker
cylinders. With tractor at idle speed, slowly work trac-
tor remote lever in the direction which would retract
the cylinder. DO NOT try to retract the cylinder. The
goal is to push the air from the lines leading to the
cylinder. This will only happen on one side which is
dependent on which way the sequence valve is shift-
ed. When the air is expelled and oil starts being
pushed out, tighten hose connection at this cylinder.
4. Slowly work tractor’s remote lever in the same direc-
tion to retract the cylinder. When it is retracted, loos-
en hose fitting at base end of the same cylinder. With
tractor at idle speed, slowly work tractor remote lever
in the opposite direction which should put oil to the
cylinder base port. When the air is expelled and oil
starts being pushed out, tighten hose connection at
this cylinder.
5. Once again, slowly work tractor’s remote lever in the
direction to fully extend the cylinder and hold it there for
a few seconds. This will shift the sequence valve which
will allow you to bleed the opposite cylinder.
6. Repeat steps 3 - 5 for opposite marker cylinder.
7. Once the system is bled, operate tractor’s remote lever
several times until both cylinders stop when fully ex-
tended. Reconnect cylinders to marker link arms.
8. The marker hydraulic system is equipped with needle
valves to control how fast each marker operates. Nee-
dle valves are built into the sequence valve body.
There are two hex adjustment screws, one for raising
and one for lowering the markers. The "raise" and
"lower" needle valves are identified by stamped mark-
ings in the valve body next to the adjustment screws.
Turn adjustment screws clockwise to slow the speed
down and counter-clockwise to speed it up. Adjust-
ments should be made for safe speeds at operating
rpm. Excessive folding speeds can cause marker
damage and may void the warranty. Be sure to tighten
the jam nuts on the hex adjustment screws to hold de-
sired settings.
The markers cycle in the following sequence:
a. right up, left up
b. right down, left up
c. right up, left up
d. right up, left down
e. sequence repeats
14048
14021
Figure 5
Bleeding the Marker Cylinder
Figure 6
Sequence Valve Speed Adjustments