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SECTION 00 - MAINTENANCE - CHAPTER 1
9
SERVICE TECHNIQUES
GENERAL
Clean the exterior of all components before carrying
out any form of repair. Dirt and abrasive dust can re-
duce the efficient working life of a component and
lead to costly replacement.
Time spent on the preparation and cleanliness of
working surfaces will pay dividends in making the job
easier and safer and will result in overhauled compo-
nents being more reliable and efficient in operation.
Use cleaning fluids which are known to be safe. Cer-
tain types of fluid can cause damage to 'O' rings and
cause skin irritation. Solvents should be checked that
they are suitable for the cleaning of components and
also that they do not risk the personal safety of the
user.
Replace 'O' rings, seals or gaskets whenever they
are disturbed. Never mix new and old seals or 'O'
rings, regardless of condition. Always lubricate new
seals and 'O' rings with hydraulic oil before installa-
tion.
When replacing component parts, use the correct
tool for the job.
HOSES AND TUBES
Always replace hoses and tubes if the cone end or
the end connections on the hose are damaged.
When installing a new hose, loosely connect each
end and make sure the hose takes up the designed
position before tightening the connection. Clamps
should be tightened sufficiently to hold the hose with-
out crushing and to prevent chafing.
After hose replacement to a moving component,
check that the hose does not foul by moving the com-
ponent through the complete range of travel.
Be sure any hose which has been installed is not
kinked or twisted.
Hose connections which are damaged, dented,
crushed or leaking, restrict oil flow and the productiv-
ity of the components being served. Connectors
which show signs of movement from the original
swagged position have failed and will ultimately sep-
arate completely.
LB 7~115
A hose with a chafed outer cover will allow water
entry. Concealed corrosion of the wire reinforcement
will subsequently occur along the hose length with
resultant hose failure.
Ballooning of the hose indicates an internal leakage
due to structural failure. This condition rapidly de-
teriorates and total hose failure soon occurs.
Kinked, crushed, stretched or deformed hoses gen-
erally suffer internal structural damage which can re-
sult in oil restriction, a reduction in the speed of oper-
ation and ultimate hose failure.
Free-moving, unsupported hoses must never be al-
lowed to touch each other or related working sur-
faces. This causes chafing which reduces hose life.
'O' RING FLAT FACE SEAL FITTINGS
When repairing 'O' ring face seal connectors, the fol-
lowing procedures should be observed.
A
WARNING
A
NEVER DISCONNECT OR TIGHTEN A HOSE OR
TUBE THAT IS UNDER PRESSURE. IF IN DOUBT,
ACTUATE THE OPERATING LEVERS SEVERAL
TIMES WITH THE ENGINE SWITCHED OFF
PRIOR TO DISCONNECTING A HOSE OR TUBE.
1. Release the fittings and separate the hose or
tube assembly, then remove and discard the 'O'
ring seal from the fitting.
2. Dip a new 'O' ring seal into clean hydraulic oil
prior to installation. Install a new 'O' ring into the
fitting and, if necessary, retain in position using
petroleum jelly.
3. Assemble the new hose or tube assembly and
tighten the fitting finger tight, while holding the
tube or hose assembly to prevent it from turning.
4. Use two suitable wrenches and tighten the fitting
to the specified torque according to the size of the
fitting. Refer to the following torque chart.
NOTE: To ensure a leak-free joint is obtained, it is im-
portant that the fittings are not over or under torqued.
604.56.061.00 09/2000
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