4.9 Releasing internal pressure of hydraulic system

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.

A.RELEASING HYDRAULIC SYSTEM AND

TANK PRESSURE

HYDRAULIC OIL LEVEL CHECK POSITION

BUCKET DOZER BLADE

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.

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.

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.

HYDRAULIC TANK

LEVEL GAUGE

AIR PLUG

F19384

FUEL TANK

F19385

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.