Komatsu Utility 69001, Operation & Maintenance Manual

Page: 220 / 276

SERVICE PROCEDURE
MAINTENANCE
4-42
PROCEDURE FOR BLEEDING AIR IN HYDRAULIC SYSTEM 4
See “STARTING ENGINE (3-68)“.
Since the engine must be started and the blade must be operated, see OPERATION.
NOTICE
If the engine is run at high speed immediately after startup or a cylinder is pushed up to its stroke end, air
taken inside the cylinder may cause damage to the piston packing.
1. Bleed air from left pitch cylinder
(Powertilt, Power pitch dozer only)
Bleeding air from the hydraulic system is required when removing and installing the work equipment or when
making the repairs.
2. Start the engine and run it at low idle for at about 5 min-
utes.
3. Raise the blade.
4. Bleeding air in the tilt hydraulic circuit by repeating left and
right tilt operation five to ten times.
5. Bleeding air from the bottom of left cylinder by operating
the blade to pitch forward and backward 5 to 10 times
repeatedly.
6. Set the left and right cylinders at the neutral position, then
carry out the following operations 5 to 10 times to bleed the
air from the head end of the left pitch cylinder.
(1) Forward pitch
→
(2) Left tilt
→
(3) Right tilt
→
(4) Backward pitch
7. Bleeding air from cylinders
8. Run the engine at low idle, and extend and retract each
cylinder 4 to 5 times, taking care that a cylinder is not
moved to the end of its stroke. (Stop the cylinder approx.
100 mm short of its stroke end)
9. Next, operate each cylinder 3 to 4 times to the end of its
stroke.
10. Finally, operate each cylinder 4 to 5 times to the end of its
stroke to completely remove the air.