TROUBLESHOOTING WITHOUT A DIAGNOSTIC CODE - CONTINUED
Table 7. Hydraulic System Troubleshooting.
TEST OR INSPECTION
WARN I N G
Personal injury or death can reult from sudden machine move-
DO NOT disconnect or remove anyhydraulic system line or fitting
unless engine is shut down and hydraulic system pressure has been
relieved. Tighten all connections before applying pressure. Escaping
hydraulic fluid under pressure can penetrate skin, causing injury to
At operating temperature, hydraulic oil is hot. Allow hydraulic oil to
cool before disconnecting any hydraulic lines. Failure to follow this
warning may result in injury to personnel.
CAU T I ON
Wipe area clean around all connections to be opened during removal. Cap
lines and hoses and plug openings after removing lines. Contamination of
system could result in premature failure.
N OT E
Tag hoses prior to removal to ensure correct installation.
Use container to catch any fluidthat may drain from hoses or sys-
tem. Dispose of fluid IAW local policy and ordinances. Ensure all
spills are cleaned up.
On 966H machines, each valve has poppets which act as load check
valves. Poppets close ports so there is almost zero drift of imple-
ments. Relief valves in auxiliary circuit and in tilt circuit protect
components from pressures in circuits when control valves are in
Oil pressure for opening relief vaves for main system and auxiliary
circuits must be within specifications. Pressures that are too low will
cause a decrease in lifting force and dig characteristics. Pressures
that are too high will cause a decrease in life of hoses and other com-
Circuit drift is caused by leakagepast cylinder pistons, O-ring seals
in control valves, check valves that do not seat correctly, or makeup
valves that do not seat correctly. Poor adjustment of control valves
or incorrect fit may also contribute to circuit drift.
Cycle times that are longer than no mal can result from oil leakage,
pump wear, or pump speed.
If basic tests indicate a leak in crcuit, install a flow meter and per-
form a test.
Many of these problems can create diagnostic or event codes in ET.
These codes can help find the root cause of a problem. ET should be
used to retrieve logged and activate codes.