Ram Creep Tests - All Services - jcb JS300 Service Manual

If ram creep is suspected the following procedures must be
carried out to define if the leakage is within tolerance. Ram
creep can be caused by a number of reasons: Cylinder/
Piston Leakage, Spool Leakage, ARV Leakage.
Note: This service procedure should be carried out with a
standard empty bucket fitted
Note: The procedures are not applicable for rams fitted
with hose burst protection valves.
!M
WARNING
Hydraulic Pressure
Hydraulic fluid at system pressure can injure you.
Before connecting or removing any hydraulic hose,
residual hydraulic pressure trapped in the service
hose line must be vented. Make sure the hose service
line has been vented before connecting or removing
hoses. Make sure the engine cannot be started while
the hoses are open.
INT-3-1-11_2
Test for Ram Creep
Boom service
1 Operate the machine to bring the hydraulic oil to a
normal working temperature of 50°C (122°F) which
can be measured using a hydraulic oil temperature
probe, refer to Section 1, Service Tools.
2 Raise the boom to it's full height.
3 Using a felt tip pen and ruler, make a mark 100mm (4
in) from the edge of the wiper seal on the piston rod.
4 Measure the actual movement of the piston rod over
a period of 10 minutes
5 Refer the measured figure to the table, if measured
figure is outside the allowed tolerance then complete
the basic checks at the end of this section.
Dipper service
1 Operate the machine to bring the hydraulic oil to a
normal working temperature of 50°C (122°F) which
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Ram Creep Tests - All Services

TE-030
9813/5100-1
Section E - Hydraulics
Hydraulic System Fault Finding
Ram Creep Tests - All Services
can be measured using a hydraulic oil temperature
probe, refer to Section 1, Service Tools.
2 Raise the boom and move the dipper to it's fully
closed position.
3 Using a felt tip pen and ruler, make a mark 100mm (4
in) from the edge of the wiper seal on the piston rod.
4 Repeat the test by raising the boom and move the
dipper to it's fully open position.
5 Using a felt tip pen and ruler, make a mark 100mm (4
in) from the edge of the wiper seal on the piston rod.
6 Measure the actual movement of the piston rod over
a period of 10 minutes
7 Refer the measured figure to the table, if measured
figure is outside the allowed tolerance then complete
the basic checks at the end of this section.
Bucket Service
1 Operate the machine to bring the hydraulic oil to a
normal working temperature of 50°C (122°F) which
can be measured using a hydraulic oil temperature
probe, refer to Section 1, Service Tools.
2 Raise the boom and move the dipper and the bucket
to the fully closed position.
3 Using a felt tip pen and ruler, make a mark 100mm
from the edge of the wiper seal on the piston rod.
4 Repeat the test by raising the boom and move the
dipper and bucket to it's fully open position.
5 Using a felt tip pen and ruler, make a mark 100mm
from the edge of the wiper seal on the piston rod.
6 Measure the actual movement of the piston rod over
a period of 10 minutes
7 Refer the measured figure to the table, if measured
figure is outside the allowed tolerance then complete
the basic checks at the end of this section.
Note: The table indicates the MAXIMUM permitted ram
movement.
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