DX380LC-7
Operation
3-68
Machine with a Boom Lock Valve
When you must manually lower the boom if the engine has
stopped and cannot be started, or the hydraulic system is
disabled, the operator can still lower the boom, using the
following procedure, when machine is equipped with a boom
lock valve.
1.
Relieve the pressure in the hydraulic system before
manually lowering the boom.
A.
Turn starter switch to "I" (ON) position.
B.
Move the safety lever to "UNLOCKED" position.
C.
Move the joysticks and travel levers/pedals forward
and backward to relieve accumulator pressure.
D.
Turn key to "O" (OFF) position and remove from
starter switch.
2.
Loosen locknut (1, Figure 123) of the lock valve.
3.
Slowly turn check valve (2, Figure 123) clockwise until
check valve stops. The boom will lower to the ground.
4.
Make sure that front attachment has been completely
lowered onto the ground. Tighten check valve (2, Figure
123).
5.
Tighten locknut (1, Figure 123) to a torque of 39.2 N.m
(4 kg.m, 28.9 Ib ft).
After completion of the manual boom lowering, make necessary
repairs before you operate the machine again.
NOTE:
For additional information, contact your DOOSAN
dealer.
WARNING
AVOID DEATH OR SERIOUS INJURY
Boom weight can cause cylinder oil pressure to reach relief
pressure of the boom lowering control device when the
boom is supported by one cylinder. Boom can lower
suddenly, causing death or serious injury.
To avoid death or serious injury, be sure no one is under or
near the work tool before manually lowering the boom.
Keep all personnel and bystanders away from the boom
area when lowering the boom with the engine stopped.
DS1901507
1, 2
A
Detail
A
1
2
Figure 123
