Great Plains YP825A Operator Manual - Manual (Page 108)

104 YP425A, YP625A and YP825A Table of Contents Index Great Plains Manufacturing, Inc.
401-651M Table of Contents Index 2014-08-15
Hydraulic Maintenance
As with any hydraulic system, contamination is the most
common cause of performance problems and
pre-mature wear. Make a special effort to properly clean
quick couplers prior to attaching the hoses to tractor, and
never let them fall to the ground.
High Pressure Fluid Hazard:
Relieve pressure before disconnecting hydraulic lines.Wear
protective gloves and safety glasses or goggles when working
with hydraulic systems. Use a piece of paper or cardboard,
NOT BODY PARTS, to check for suspected leaks. Escaping
fluid under pressure can penetrate the skin, causing serious
injury. If an accident occurs, seek immediate medical
assistance from a physician familiar with this type of injury.
Bleed only at JIC and NPT fittings.
Never try to bleed a QD (Quick Disconnect) fitting.
Avoid bleeding at ORB fittings. The O-ring is likely to be
torn if any pressure remains in the circuit.
System Contamination Risk:
Always use liquid pipe sealant when adding or replacing NPT
(National Pipe Thread, tapered thread) pipe-thread fittings. To
avoid cracking hydraulic fittings from over tightening, and to
keep tape fragments from clogging filters, do not use plastic
sealant tape.
Over-Torque and Leak Risks:
JIC (Joint Industry Conference 37
° Flare) fittings do not
require high torque. Excess torque causes leaks. JIC and
ORB (O-Ring Boss) fittings do not require sealant.
Bleeding Lift Hydraulics
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.
If it is necessary to further bleed lift system, see “Lift
Cylinder Bleeding” on page 105.
Bleeding Marker Hydraulics
To fold properly, the marker hydraulics must be free of
air. If the markers fold in jerky, uneven motions.
As the marker cylinders are encased within the main tool
bar, it is not practical to bleed them at cylinder fittings.
Remove air from the system by slowly cycling fold and
unfold several times.
JIC Torque Chart
Size Foot-Pounds N-m
7 ⁄
16
-20 11-12 15-16
1 ⁄
2
-20 15-16 20-22
5 ⁄
16
-18 18-20 24-28
3 ⁄
4
-16 38-42 52-58
7 ⁄
8
-14 57-62 77-85
11 ⁄
16
-12 79-87 108-119