jcb JS300 Service Manual page 905

Item Symptoms Related Parts
Piston rod
Piston rod
1 sliding part oil
leakage
Rod packing
(Buffer ring, U-
E-244
Trouble
On the sliding surface, there are
scratches and rust that can be
felt by the fingernail.
The plating is peeling.
Foreign matter is biting into the
inner and outer surfaces of the
packing.
There is a scratch on the inner
and outer surface of the packing.
The lip and groove parts are
locally carbonized (burned).
Packaging rubber elasticity is
gone and breaks into pieces.
ring)
Lip is deficient all around.
Hydraulic System Fault Finding
Table 11.
1 Use an oil stone and remove the scratch
and make the sliding surface smooth.
(Less than 1.5 S). If oil leakage continues
even though the rod surface is made
smooth, the scratch may cause damage
to the U-ring and other seals, so
disassemble and inspect.
2 If the scratches and rust cover such a
wide area that they cannot be repaired by
an oil stone, replace the piston rod and U-
ring, wiper ring and seals and the piston
rod bearing member.
Re-plate or replace the piston rod. Also inspect
the seal and piston rod bearing member and
replace if damaged.
Remove foreign matter. If there is damage to
packing, replace it.
Replace.
Possibly due to burning caused by adiabatic
compression from air remaining inside the
ram. After replacing the packing, first operating
the ram at low-pressure, low speed to
sufficiently bleed the air.
The packing life or hydraulic oil deterioration
and high temperature are possible reasons.
1 Renew hydraulic oil.
2 Check the hydraulic oil temperature
(Below 80 C is advisable).
3 Check if high temperature locally.
Replace.
It is possible that abnormal high pressure is
working on the packing.
1 Check the operation pressure, cushion
pressure.
2 Part which is attached to the buffer ring
may be abnormal. Inspect the buffer ring.
9813/5100-1
Section E - Hydraulics
Hydraulic Rams
Treatment
E-244