Bush Hog CBH80 - Manual (Page 21)

TROUBLESHOOTING (Continued)
Problem Cause Correction
Machine loses power after Diverter valve on prime move Diverter valve may need rebuilding or
operating satisfactorily leaking or bypassing oil internally replacing.
initially through valve to reservoir
Excessive back pressure Relieve condition. Restriction may be
from outlet to reservoir.
Relief valve setting in backhoe Relief pressure will have to be checked
control valve too low or defective and corrections made. Backhoe
system pressure is 2000 PSI (CBH60),
2250 PSI (CBH70), 2550 PSI (CBH80),
Relief valve may need cleaning and
overhauling, or entire cartridge must be
replaced.
Loss of power in lift or Spool not moved to full stroke Check spool travel - should be .16”
crowd cylinder, but other either way or a total of .32” for CBH60.
cylinders function properly Check spool travel- should be .28”
either way, or a total of .56”. for
CBH70 and CBH80.
Overload relief valve in the control Clean relief carefully but do not disturb
valve stuck open or malfunctioning its pressure setting as it cannot be field
calibrated, or replace cartridge.
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 oil line removal and
replacement, and during any cylinder
work.
Loss of power in any one Loose oil line connections, Tighten all hose connections and
cylinder, including lift leaks in line or broken lines replace any damaged O-rings at
and crowd leaking O-ring fittings. Check and
replace any damaged hoses and lines.
Restrictions in oil lines Check and replace any damaged hoses
and lines. Check for pinched hoses.
Oil is bypassing cylinder piston, Replace or rebuild the cylinder; replace
scored piston, worn piston packing damaged parts.
or defective piston assembly
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