Lull 6K Service Manual - Manual (Page 149)

Supply, Pressure, and Return Hydraulics
Service Manual — Models 644B, 6K, 844C, 8K, 1044C, 10K 5-5
KEEP DIRT AND OTHER CONTAMINANTS OUT OF THE SYSTEM!
Small particles can score valves, seize pumps and clog orifices, causing
expensive repair jobs.
Steam clean or use solvents to clean the area of the machine around a
hydraulic component before it is removed.
When steam cleaning or using water to clean a machine, be sure the
reservoir breather filter is protected to keep water out of the system.
Use caps or plugs to cover ends of disconnected lines, or to plug openings
when working on a hydraulic system.
When removing parts for service, clean them with a suitable solvent and
store them in plastic bags or other clean containers until they are installed
again.
Thoroughly rinse the cleaned parts, and dry them using compressed air.
Protect the parts immediately with a coating of rust preventive oil.
A clean work bench is an absolute must when servicing hydraulic
components. An industrial-type vacuum cleaner is a valuable aid in
removing dust, dirt, and tiny metal particles from the work area.
Check the condition of the tools you use and make sure they are clean.
Use hammers made of plastic or leather so there is no danger of metal
chips getting into components.
Despite all the precautions you take when working with a hydraulic system,
some contaminants will get into the system anyway. High quality hydraulic
oils keep these contaminants in suspension and the filters will collect them
as the oil passes through. A high quality hydraulic oil contains many
additives which work to keep contaminants from damaging the system.
However, these additives lose their effectiveness after a period of time.
Therefore, change the oil at recommended intervals to make sure the
additives do their job.
The system filter can absorb only a limited amount of dirt particles and
other contaminants from the oil. Therefore, replace the filter element at the
recommended intervals so the cleaning process can be maintained.
Checking Hydraulic Lines
Inspect hydraulic lines and fittings for gouges, nicks, kinks, leaks, and
collapsed or deteriorating hoses.
Note: Even small leaks can be detected by oil stains or build-up of dirt or other
foreign material in a suspect area.
Replace any tube lines that are pinched or dented.
Replace a hose if any of the following conditions exist:
• Any evidence of hydraulic oil leakage at the surface of the hose or its
junction with the metal end couplings.
• Any blistering or abnormal deformation to the outer covering of the
hose.