HYDRAULIC SYSTEM MLC300 SERVICE/MAINTENANCE MANUAL
2-24
Published 11-22-17, Control # 257-02
Changing Hydraulic Oil
See Figure 2-15 for the following procedure.
Drain and refill the hydraulic system every 1,000 hours or
semiannually, whichever comes first, unless an alternate
interval has been established through an oil analysis
program.
1. Operate the crane until the hydraulic oil is at its normal
operating temperature. This helps remove impurities
from the system.
2. Stop the engine.
3. Vent the tank using either the Schrader valve (5) or the
vent valve (6).
4. Put the free end of the drain hose (3, Figure 2-22
) into a
suitable container to catch the hydraulic oil. See the
Lubrication Guide (Section 9 in this manual) for the
hydraulic system capacity.
5. Verify the shut-off valves (12, 13, 14, and 15) are open.
6. Screw the quick-drain drainer (1, Figure 2-22
) onto
either of the quick-drain valves (11) on the bottom of the
hydraulic tank.
7. Completely drain the hydraulic tank and discard the
hydraulic oil according to local environmental
regulations.
8. Remove the access cover (10) from the hydraulic tank.
Take care to prevent dust and wind-blown dirt from
entering the tank while the access covers are off.
9. Clean out any sediment from inside the hydraulic tank.
10. Service the suction strainers (see Servicing Suction
Strainers on page 2-23).
11. Replace the filter elements (see Replacing Hydraulic
Filters on page 2-20).
12. Replace the desiccant breather cartridge (see Replacing
the Desiccant Breather Cartridge on page 2-20).
13. Using a new seal, securely fasten the access cover to
the hydraulic tank.
14. Fill the hydraulic tank to the Full Cold Level mark on the
oil level sight gauge (4). Use the proper hydraulic oil
listed in the Lubrication Guide.
Do not fill the hydraulic tank to 100% as indicated in the
Crane Systems Bar of the main display. Oil will flow out
of the breather.
Fill the tank using one of the following methods:
• Pump oil through the power-fill coupling (3). The oil
will be filtered by Filter 1.
• On past production cranes only, fill the tank through
the fill cap (21). If this method is used, the oil must
be filtered through an owner-supplied 10-micron
filter.
15. Close the Schrader valve (5) and vent valve (6).
16. Start the engine and allow the hydraulic system to reach
its normal operating temperature.
17. Check for leaks and correct them as required.
18. Stop the engine.
19. Check the hydraulic tank level and fill as required.
NOTE: If the hydraulic system was extremely dirty (gum or
lacquer formation on parts indicated by erratic,
jerky, or sluggish operation), repeat the procedure
after 48 hours of operation.
Servicing Pumps
It is not necessary to drain the hydraulic tank when servicing
the hydraulic pumps. To service the pumps, close the
corresponding hydraulic tank shut-off valve (12, 13, 14, or
15, Figure 2-15
).
Item Description
1 Quick-Drain Drainer
2 Hose Clamp
3Drain Hose
Stored in Parts Box Supplied with Crane
FIGURE 2-22
CAUTION
Contamination Hazard!
Do not fill the hydraulic tank through the breather opening.
Harmful contaminants will enter the hydraulic system.
Damage to pumps and motors can occur.
CAUTION
Avoid Damage to Pumps!
Open the hydraulic tank shut-off valves before starting the
engine. Failing to perform this step will result in damage to
the pumps from cavitation.
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