SECTION 3 – TROUBLESHOOTING
3-8
USTC
January 15, 2001
TROUBLE
PROBABLE CAUSE
REMEDY
Table 3-4. Hydraulic Components (continued)
Boom will not lower.
Hydraulic oil level low.
Restricted or broken supply line.
Malfunctioning hydraulic pump
section.
Control cable broken, kinked or
disconnected.
Check valve in control valve
section inlet stuck in closed
position.
Excessive oil leak past cylinder
piston seal.
Worn control valve spool.
Hydraulic lines incorrectly
connected at control valve.
Holding valve in lift cylinder
stuck in closed position.
Hydraulic oil level low.
Restricted or broken supply line.
Malfunctioning hydraulic pump
section.
Excessive oil leak past lift
cylinder piston seal.
Worn control valve spool.
Boom pivot pin seized or
otherwise damaged.
Malfunctioning holding valve on
cylinder.
Defective cylinder packing.
Worn control valve spool.
Malfunctioning holding valve on
cylinder.
Add oil.
Remove line and clear
obstruction or replace line.
Repair or replace pump.
Repair or replace control cable.
Repair or replace check valve.
Repair or replace cylinder.
Check pressure delivery from
control valve and repair or
replace valve.
Connect hydraulic lines properly.
Check for presence of pilot
pressure at return valve and
repair or replace.
Add oil.
Remove line and clear
obstruction or replace line.
Repair or replace pump.
Repair or replace cylinder.
Check pressure delivery from
control valve and repair or
replace valve.
Replace pivot pin and bushings.
Replace holding valve.
Repair or replace cylinder.
Check pressure delivery from
control valve and repair or
replace valve.
Replace holding valve.
Boom raises and lowers
erratically.
Boom lowers with control lever in
neutral.