Nabtesco GM Series - Chapter 7 TROUBLESHOOTING

GM Series
TM19040 P.29/31
C
C
h
h
a
a
p
p
t
t
e
e
r
r
7
7
T
T
R
R
O
O
U
U
B
B
L
L
E
E
S
S
H
H
O
O
O
O
T
T
I
I
N
N
G
G
If there is any problematic phenomenon, check the cause and take measures according to the following
table.
If the measure marked with a circle is needed, stop the machine operation and contact our customer
support.
Phenomenon 1 Phenomenon 2 Possible cause Countermeasure
Does not rotate.
No pressure is applied.
Low set pressure of the relief valve Set the pressure correctly.
Malfunction of the pump Repair.
Malfunction of the direction-switching
valve
Repair.
Pressure is applied.
Malfunction of the brake valve Replace or repair the brake valve. ○
Malfunction of the hydraulic motor Repair. ○
Damage of the gears (reduction
gears)
Replace GM. ○
Overloaded Remove the load.
Oil leakage
From the mating surfaces
Scratches on mating surfaces
Polish the surface using a grindstone, polishing paper,
and so on.
○
Looseness of bolts Retighten the bolts.
From the case
Looseness of plugs Retighten the plugs.
Cracks with stones Replace GM. ○
From the floating seal
Intrusion of earth and sand
Wash away the earth and sand from the floating seal.
Wear of sliding surfaces Replace GM. ○
O-ring creep Replace GM. ○
From the hydraulic motor
Looseness of bolts Retighten the bolts.
O-ring damage Replace the O-rings. ○
Scratches on the sealing surface
Polish the surface using a grindstone, polishing paper,
and so on.
○
Rotated by load
during use
Increased internal or external
drain
Reduced volumetric efficiency of the
hydraulic motor
Replace GM.
○
Increased internal leakage (drain) of
the brake valve
Replace or repair the brake valve. ○
Parking brake is not working
Damage to springs Replace the springs.
○
Friction plate wear Replace the friction plate and the mating plate. ○
Blockage of the oil passage
by contaminants
Replace or repair the brake valve. ○
For the item marked with a circle, contact our customer support.