jcb JS200 Service Manual page 390

Section E
78 - 4
Trouble Shooting (continued)
Item Symptoms Related Parts
Poor
operation
cylinder tube
4-1
Movement Cylinder tube
not smooth
4
4-2
Inner oil
leakage.
Piston rod
extends when
work stops or
lowers
Cylinder tube
abnormally
during work.
Also, specified
operating
speed is not
achieved.
Note: Hydraulic oil expands and contracts due to changes in temperature and pressure. Accordingly, the ram also
expands and this can be mistaken for internal leakage. When inspecting for internal leakage, do so at set conditions.
9803/6400
Bending is more than the
Piston rod specified limit.
(Bending distortion:
Refer to maintenance standards)
There is a recess
Abnormal wear, damage of sliding
Piston rod area
cylinder rod
sliding part Foreign matter intruding on piston
and cylinder head sliding area
Scratches, wear are present
Piston seal
Scratches, rust on inside
Piston Nut Loose nut
Valves Leak from valve
Hydraulics
Hydraulic Rams
Trouble Treatment
• Replace with new part.
The seal and sliding part material may be
damaged too, so inspect. If abnormal,
replace.
• Replace with new part.
As above, inspect the seal and sliding
part material.
• Replace with new part.
As above, inspect the seal and sliding
part material.
• Remove foreign material.
As above, inspect the seal and sliding
part material.
• Replace with new part.
Inspect the cylinder tube inner surface
also.
• Remove the scratches, rust by honing or
with an oil stone and make the surface
smooth.
If the scratch is deep and cannot be
repaired, replace cylinder tube.
• Replace piston seal.
• Tighten to specified torque.
• Inspect the valve leakage amount and
service.
Section E
78 - 4
Issue 1