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General Information
Hydraulic Hoses
Hydraulic hoses are subject to extreme conditions such
as pressure differentials during operation and exposure
to weather, sun, chemicals, very warm storage condi-
tions, or mishandling during operation and mainte-
nance. These conditions can cause damage or
premature deterioration. Some hoses are more suscep-
tible to these conditions than others. Inspect the hoses
frequently for signs of deterioration or damage.
When replacing a hydraulic hose, be sure that the hose
is straight (not twisted) before tightening the fittings.
This can be done by observing the imprint on the hose.
Use two wrenches; hold the hose straight with one
wrench and tighten the hose swivel nut onto the fitting
with the other wrench.
Before disconnecting or performing any work
sure in this section.
pressure. Use paper or cardboard, not hands,
to search for leaks. Hydraulic fluid escaping
under pressure can have sufficient force to
cally removed within a few hours by a doctor
WARNING
on hydraulic system, relieve all pressure in
system. See Relieving Hydraulic System Pres-
Keep body and hands away from pin hole leaks
or nozzles that eject hydraulic fluid under high
penetrate the skin and cause serious injury. If
fluid is injected into the skin, it must be surgi-
familiar with this type of injury. Gangrene may
result from such an injury.
Hydraulic Fitting Installation
O–Ring Face Seal
1. Make sure both threads and sealing surfaces are
free of burrs, nicks, scratches, or any foreign material.
2. Make sure the O–ring is installed and properly
seated in the groove. It is recommended that the O–ring
be replaced any time the connection is opened.
3. Lubricate the O–ring with a light coating of oil.
Nut
Sleeve
Seal
Body
4. Put the tube and nut squarely into position on the
Figure 1
face seal end of the fitting and tighten the nut until finger
tight.
5. Mark the nut and fitting body. Hold the body with a
wrench. Use another wrench to tighten the nut to the cor-
Final
rect Flats From Finger Tight (F.F.F.T.). The markings on
Position
the nut and fitting body will verify that the connection has
Mark Nut
and Body
been tightened.
Initial
Size F.F.F.T.
Extend Line
Position
4 (1/4 in. nominal hose or tubing) 0.75 + 0.25
Finger Tight After Proper Tightening
6 (3/8 in.) 0.75 + 0.25
8 (1/2 in.) 0.75 + 0.25
10 (5/8 in.) 1.00 +
0.25
Figure 2
12 (3/4 in.) 0.75 + 0.25
16 (1 in.) 0.75 +
0.25
Hydraulic System Page 4 – 4 ProCore 648