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Troubleshooting (Continued)
Problem Cause Correction
Slow operation of machine Relief valve setting in backhoe Relief pressure will have to be checked
(lack of power) all cylinders control valve too low or defective and corrections made. Backhoe
system pressure is 2400 PSI. Relief
valve may need cleaning and over-
hauling, or entire cartridge must be
replaced.
Spongy or jerking action Low oil supply in reservoir Fill to proper level.
of cylinders and/or noisy
operation Air in system Bleed all circuits of air by operating
machine at maximum oil flow and
through full movements.
Oil viscosity too heavy, or Use recommended hydralic fluid. Run
oil is not at operating machine until oil reaches operating
temperature temperature.
Pump not running Check pump drive to be sure it is
engaged.
Lift, crowd or bucket Damaged or worn spool Replace spool end seals.
cylinders drop under load seals
when control spools
shifted from neutral Problems involving the control This valve is a precision device and is
valve not intended for any extensive field
adjustment or repair. Field replace-
ment parts are limited to seal kits,
cartridges, valve sections and tie rods.
Replacement of these parts, the
opening of check cavities and certain
relief cavities to examine for trapped
dirt, or resetting of the main relief valve
with the use of good pressure gauge,
should be referred to qualified service
personnel.
Dirt and shreds of packing material are
the usual causes of valve malfunction.
Be sure the reservoir oil supply is kept
clean and only factory supplied
packings are used in cylinder repair.
Everything must be clean and free of
dirt during the oil line removal and
replacement, and during any cylinder
work.
Load drops or settles Loose oil line connections, Tighten all hose connections and
leaks in line or broken lines replace any damaged O-rings at
leaking O-ring fittings. Check and
replace any damaged hoses and lines.
Oil is bypassing cylinder piston, Replace or rebuild the cylinder; replace
scored piston, worn piston damaged parts.
packing, or defective piston
assembly
Worn or damaged rod seals on Repack cylinder. Rebuild cylinder,
cylinder; external leaks replacing damaged parts as necessary.
Worn control valve Replace the control valve.
Damaged or worn spool seals Replace spool end seals.