SECTION IV - MAINTENANCE
4.9 RELEASING INTERNAL PRESSURE OF HYDRAULIC SYSTEM Release the internal pressure of hydraulic system before carrying out maintenance work such as hydraulic oil change, return filter change, suction strainer cleaning, cylinder repair. Pressurize the hydraulic oil tank after maintenance and releasing air in the system.
HYDRAULIC OIL LEVEL CHECK POSITION
BUCKET
DOZER BLADE
A. RELEASING HYDRAULIC SYSTEM AND TANK PRESSURE
WARNING • Never change oils or filters on a machine that has just finished working. Allow machine to cool first until oils and fluids are warm, not hot. • Release hydraulic tank pressure before working with any hydraulic component, according to the procedures provided below. • When replacing any hose or seals, make sure the attachments are well secured to avoid sudden movement of attachment. Slowly remove bolts to release any hydraulic pressure during disassembly.
HYDRAULIC TANK
LEVEL GAUGE F19384
FUEL TANK
1. Place the machine in the “hydraulic oil check position” as shown in the right figure. Fully retract the arm cylinder and bucket cylinder, then lower the boom to place the bucket on the ground, and lower the dozer to the ground. 2. In case of pilot operating lines (boom, arm, bucket, swing) stop the engine then operate the control levers to release pressure of each line.
AIR PLUG
F19385
NOTE: The internal pressure of the hydraulic system can be released only by the above method. 3. Set the safety lock lever to “LOCKED” position. 4. Make sure the hydraulic oil temperature is below 40°C (104°F). 5. Slowly loosen the air plug on the upper side of the hydraulic oil tank to release internal pressure. NOTE: Remove the AIR PRESSURE CAP after the engine has cooled down to touchable with a hand. Slowly loosen the cap to release the inside pressure. Remove the AIR PRESSURE CAP after all pressure is released.
6. Temporarily install plug until completion of the inspection and maintenance procedures. 7. In case of Manual operating lines (Travel, Swing, Dozer, Service), operate each control levers to release pressure of each line after stopping engine. Now inside pressure in the hydraulic oil tank is fully released. Proceed the inspection and maintenance procedures for the hydraulic system.
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