jcb JS200 Service Manual page 457

Section F
5 - 1
Fault Finding
Piston Motor
Fault
1. Motor does not
run
2. Motor revolution
speed is
insufficient
3. Motor revolution
speed varies
greatly
4. Oil leaks
9803/6400
Transmission
Motor/Gearbox
Possible cause
1. Device other than the piston motor or
reduction gear may have malfunctioned.
2. Sliding area of motor is abnormally worn
allowing the pressurised oil to escape.
3. Improper operation resulting from
damage of important motor part. In this
case, abnormal noise is heard from the
motor itself.
4. Relief valve is activated because the
motor is excessively loaded.
1. Oil not supplied to motor at specified
rate due to problems in hydraulic pump,
pressure control valve, etc.
2. Specified revolution speed cannot
be achieved due to reduced
volume efficiency of motor.
1. Pressurised oil escaping
through the drain port due to wear
on the sliding area of the motor.
Also, revolution speed variation
resulting from wear in the bearing.
2. Motor load is excessive and the
automatic 2-speed function is working.
1. Oil leaks due to damage of the oil seals
or 'O'-rings.
Countermeasure or remedy
Check whether or not the specified
pressurised oil is delivered to the motor
input side and then inspect each device
and repair if necessary.
Replace the excessively worn part. Remove
scratches and burrs from the surface and
completely clean all parts. Reassemble the
parts.
Disassemble and replace the damaged part.
Completely clean all parts and reassemble.
Check the load state and operate the
machine under a load which matches the
relief pressure.
Check whether the specified pressurised
oil is delivered to the motor input side
and then inspect each device and
repair if necessary.
After disassembly, check for abnormal
wear of the sliding area and repair or
replace worn parts.
Disassemble and replace excessively
worn parts. Completely clean all parts
and reassemble them.
Check the load state and operate the
machine under a load which matches the
automatic 2-speed set pressure.
Replace a broken oil seal or 'O'-ring with a
new one. When inserting the oil seal, be
careful not to damage the lip. Since the safe
working temperature limit of the oil seal
and 'O'-ring is up to 80°C, it is necessary to
take steps to prevent the hydraulic oil
temperature from exceeding 80°C.
Section F
5 - 1
Issue 1