Maeda MK0003, Руководство по обслуживанию, Страница: 141 / 348

2-113
13.4 COUNTER BALANCE VALVE (FOR TELESCOPIC AND DERRICK
CYLINDERS)
13.4.1 STRUCTURAL DRAWING
Specifications
Max. working pressure 20.6 MPa [210 kgf/cm
2
]
Withstand pressure 30.9 MPa [315 kgf/cm
2
]
Rated flow rate 50L/min
Allowable leak amount 0.05 cc/min or less (pressurizing 20.6 MPa [210 kgf/cm
2
] from B port)
Pilot pressure 1.18
+0.3
MPa [12
+3
kgf/cm
2
] with the valve open
Valve tightening torque 0.9 - 1.0 MPa [9 - 10 kgf-m]
Check cracking pressure 0.098 MPa [1 kgf/cm
2
]
Operating temperature range -10 to +80
˚
C
13.4.2 FAILURE CAUSE AND COUNTERMEASURE
Abnormal Phenomenon Cause Remedy
The telescopic cylinder and
derrick cylinder contract
during work.
(Boom lowers)

Failure of check seat part (1) or (2) or
biting of foreign matter

Damage to O-ring (1) or (2), (3) and
(4)

The pilot hole (

0.3) is clogged with
foreign matter and the spool is left
moved, resulting in the check seat (2)
being left open.

Removal of foreign matter

Replacement of O-ring

Removal of foreign matter from the
pilot hole
The telescopic cylinder and
derrick cylinder do not
contract (boom does not
lower), or speed during
contraction is very fast.

Pilot hole (

0.3) is clogged with foreign
matter.

Removal of foreign matter from the
pilot hole
Width across flat 32
Check seat part (2)
Check seat part (1)
O-ring (1)
O-ring (4)
Width across flat 38
Tightening torque 9 to 10 kg
･
m
Spool
O-ring (2)
O-ring (3) Pilot hole (

0.3)