Komatsu 75001, Shop Manual

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SEN03849-00
40-500
16
WA250, 250PZ-6
500 Troubleshooting of hydraulic and mechanical system (H-mode)
H-10 The brake does not work or does not work well
H-10 The brake does not work or does not work well
1
Ask the operator about the following:
q
Has the brake come not to work suddenly?
o Breakage of brake equipment
q
Has the brake come not to work gradually?
o Wear of lining and disc, defective seal
Inspection before diagnosis
q
Is the oil level in the hydraulic tank appropriate?
q
Is the play of brake pedal appropriate?
q
Oil leak from brake tube and connector, deformation of
tube.
q
Tire air pressure and state of tire tread.
Check abnormality
q
Measure the braking force and check referring to the stan-
dard value table if the brake does not work practically.
Cause
a b c d e f g h i j k
Def
ect
iv
e br
ak
e
p
is
ton
se
al
in axl
e
Def
ect
iv
e oper
at
ion of
b
rak
e
pi
st
on i
n
a
x
le
Def
e
ct
iv
e sl
ack adj
ust
e
r
W
e
ar
or
ab
nor
m
al
it
y of
br
ak
e l
ini
ng
in
ax
le
M
et
al
cont
a
c
t due
t
o
com
pl
et
e
wear
of
br
ake l
ini
ng i
n
a
x
le
M
ixi
ng o
f
ai
r
in
br
ake
ci
rc
ui
t
Def
e
ct
i
n
si
de
br
ake
va
lv
e
Def
e
ct
iv
e seal
o
f acc
u
m
u
la
to
r
p
is
ton
, i
n
suf
fici
ent
gas
pr
ess
u
re
Def
ect
iv
e oper
at
ion of
a
ccum
ul
at
or
cha
rge
va
lv
e
Def
ect
iv
e
br
ak
e p
um
p (
F
or
c
har
ge)
Def
ect
iv
e br
ak
e
linkag
e
No.
Remedy
Diagnosis
E
X
E
X X
E
X
E
X
E
X
E
X X
E
X A
1
When the brake pedal is stepped on, only a little resistance is felt
Q Q Q Q Q
2 When the brake pedal is stepped on, a strong resistance is felt
Q Q
3
When the brake works, an abnormal noise occurs from the axle
brake
Q Q
4
When the four wheels are jacked up, the axle is placed on a table
and the brake is applied at the first forward speed, only a specific
wheel rotates
Q Q Q Q
5
An airflow is observed in bleeding air from brake circuit, and the
brake returns to normal after the bleeding
Q
6 Brake oil leaks abnormally from the axle during inspection
Q
7 Much metal powders are mixed in the axle oil
Q
8
The brake pedal leg-power and stroke are normal, but the brake
does not work well
Q Q Q Q Q Q Q Q Q
9 The brake does not work often when the engine is stopped
Q Q Q Q Q Q
10 The accumulator is not charged, and a buzzer sounds
Q Q Q
11 The brake works after some time lag
Q Q Q