Lull 1044C-54 Series II Service Manual - Manual (Page 86)

Supply, Pressure, and Return Hydraulics
5-4 31200079
• The hydraulic system is under pressure whenever the engine is run-
ning and can hold pressure after the engine is shut down. After forks or
attachments are resting on the ground or support, make sure pressure
is relieved from all hydraulic lines and components before removing
them from the circuit.
Remember the following during inspection and maintenance of the
hydraulic system:
• Wait for fluid to cool down before disconnecting lines.
• DO NOT use your hand to check for leaks. Use a piece of cardboard or
paper to search for leaks.
• Wear appropriate eye protection.
• If anyone is injured by or if any hydraulic fluid is injected into the skin,
get medical attention immediately.
• When venting or filling the hydraulic system, loosen the filler cap slowly
and remove it gradually.
• NEVER reset any relief valve in the hydraulic system to a pressure
higher than that shown in the Specifications Section of this manual.
Cleanliness
Cleanliness is critical when servicing hydraulic systems.
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