![background image](http://html1.mh-extra.com/html/jcb/js70/js70_service-manual_3631821257.webp)
79 - 3
Section E
Hydraulics
9803/6020
Section E
79 - 3
Issue 1
Hydraulic Rams
Fault Finding (cont’d)
Item Symptoms
Related Parts
Trouble
Treatment
Foreign matter on inner
•
Remove foreign matter.
and outer diameters.
•
Renew ‘O’ ring if damaged.
•
Inspect inside tube: if any scratches or
‘O’ ring damaged.
rust, make surface smooth with oil stone.
‘O’ ring
•
Inspect cylinder head ‘O’ ring groove: if
any scratches or rust, make surface
smooth with oil stone.
•
Inspect back up ring: if any deformation
or protrusion, renew.
Confirm the above and renew ‘O’ ring.
Back up ring
Deformation, protrusion
•
Renew, with the ‘O’ ring.
Oil leakage
Looseness
•
Dismantle cylinder head and inspect
2
from cylinder
'O'-ring and back up ring.
head joint
Cylinder head
•
Check tube and cylinder head thread for
damage. If any damage, renew.
•
After inspection, tighten to specified
torque.
Bolt
Looseness, stretching, broken
Renew all bolts and tighten to specified
torque.
Abnormal bulge
Replace with new parts.
Oil leakage from connecting parts
Cylinder tube
may be caused by abnormal
pressure (including cushion
pressure). Inspect the tube for
bulges, deformation and check the
circuit pressure.
Crack in welding
Replace with new parts.
Oil leakage
•
Cracks will develop into fractures.
from pipe
Cylinder tube
Fractures are very dangerous, so if any
3
and cylinder
pipe (hollow
cracks are found, stop work immediately
tube welded
piston rod)
and replace with new parts.
seam
•
Welding on top of cracks will have no
effect.
Summary of Contents for JS70
Page 65: ......
Page 99: ......
Page 189: ...Section E Section E Hydraulics 9803 6020 Issue 1 33 4 33 4 Control Valves Control Valve 291360...