Volvo EW160E - Page 186

A
Alternative lowering without servo pressure (with line
rupture valves)
It is not possible to lower the attachment with the control lever if
the servo pressure has been lost. In such cases the attachment
should be lowered by opening the oil channel from the boom
cylinders to the tank (secondary lowering) as follows.
W
A
A
R
R
N
N
I
I
N
N
G
G
Risk of crushing.
Incorrect function of the line rupture valves may cause
uncontrolled lowering of the attachment.
D
o
o n
o
o
t
t en
t
t
e
e
r
r u
n
n
d
de
r
r t
h
h
e
e a
t
t
t
t
a
achme
n
n
t
t w
h
hen w
o
orki
n
n
g
g w
i
it
h
h t
h
h
e
e
a
l
l
t
t
e
e
r
rn
a
a
t
t
i
i
v
ve lo
w
w
e
ering f
u
u
n
nct
i
i
o
o
n
n
.
.
1 Usea4mmallenkey, select one line rupture valve and turn
the screw counterclockwise until the boom starts lowering.
The screw cannot be completely unscrewed.
2 Lower the boom to the required position.
3 Tighten the screw again to restore the valve’s function.
Tightening torque: 7 Nm (5.2 lbf ft)
L
i
i
n
n
e
e r
u
u
p
p
t
t
u
u
r
r
e
e va
l
l
v
ve
s
s
L
i
i
n
ne ru
p
pt
u
u
r
re whil
e
e ra
i
isi
n
n
g
g or l
o
o
w
w
e
e
r
ri
n
ng t
h
he b
o
o
o
o
m
m
The two interconnected line rupture valves are mounted directly
on the boom cylinder bottom sides. The main function of the
valves is to prevent the boom from making an uncontrolled
movement towards the ground in case of a line rupture between
the main valve block MCV and the line rupture valves.
If the line ruptures while raising the boom, the pressure
disappears immediately, the non-return valve closes and the
movement of the boom stops.
If there is a line rupture while lowering the boom, this will limit the
increase of the lowering speed within the control range. The
movement of the boom can be stopped or continued, as if the line
had not ruptured. When the boom is lowered, after a line rupture,
the oil has to be collected in a suitable vessel.
V1141337
2
1
3
Line rupture valves on boom cylinder
1 Boom cylinder
2 Line rupture valve left
3 Line rupture valve right
V1141338
Adjusting screw on line rupture valve
1
8
8
4
4
O
p
p
e
e
r
r
a
a
t
t
i
i
n
n
g
g i
n
n
s
st
r
r
u
u
c
ct
i
i
o
o
n
n
s
s
At
t
t
a
a
c
ch
m
m
e
e
n
n
t
t
s
s, a
l
l
t
t
e
e
r
r
n
n
a
a
t
t
i
i
v
ve l
o
o
w
w
e
e
r
r
i
i
n
n
g
g