jcb JS300 Service Manual page 902

Symptom Cause
Insufficient Wear or seizure of the
torque motor sliding surfaces.
Relief valve in the circuit
is not set correctly.
Internal damage to the
motor.
Abnormal Large amount of air
noise mixed in the oil.
Loosening of bolts or
pipes
Oil leakage O-ring is damaged
from mating
Seal face is damaged.
surfaces
Bolts are loose.
No.
a Wear of the sliding surface of balance plate
b Damage to sliding surface of cam plate
c Damage to sliding surface of the piston assemblies
d External wear to the piston assemblies
e Wear to piston bores in cylinder assembly
f Damage to Teflon ring 19 or `O'-rings
E-241
External Inspection
Open motor inlet and
outlet ports and apply 20
kgf/cm 2 (284 lbf/in
pressure to the brake
release port.Try to rotate
the shaft with a torque of
approx. 39 Nm (29 lbf ft).
Measure relief pressure.
Check if any metallic
matter is deposited in the
motor drain oil or drain
filter.
Check the oil in the tank
and motor casing.
Check if the piping
connections, attachment
mounting bolts, motor
attachment bolts or other
bolts are loose.
Check the bolt tightness. Tighten the bolts to the
Table 6.
Part Inspected
9813/5100-1
Section E - Hydraulics
Hydraulic System Fault Finding
Countermeasure
High possibility of internal
damage to the motor if
2 ) pilot the supply shaft does not
rotate smoothly when this
torque is applied.
Dismantle and inspect.
Reset to the prescribed
setting.
High possibility of internal
damage to the motor if
metallic matter is
discovered. Dismantle
and inspect.
Thoroughly bleed the air.
Tighten to the specified
torque.
correct torque.
Repair or renew the part
Repair the part or renew the motor.
Repair the part or renew the motor.
Repair the part or renew the motor.
Renew the motor.
Renew the part.
Slew Motor
Repair
Inspect the parts and
bearing according to a-e
and renew any defective
parts.K Table 6.
( T E-241)
Repair or renew
damaged parts. Renew
the motor assembly.
Renew O-rings.
Repair seal face or
renew.
Repair
E-241