4.8 CONNECTING HYDRAULIC HOSES AND PIPING JOINT
The following 2 types of joint part are used for hose piping.
4.8.1 METAL JOINT
The openings of a connector (tee or elbow) and
a hose are crimped for metallic sealing. Be
careful not to damage the seat surface during
disassembling or assembling.
1. Hose
2. Union nut
3. Connector
A. Seat surface
B. Crimping surface of hose cap
C. Crimping surface of connector
A
3
2
1
B
C
METAL JOINT
4.8.2 O-RING SEAL JOINT
An O-ring equipped with the hose mouth fitting
seals the hydraulic pressure of the joint part to
prevent the oil leakage.
The tightening torque for the piping joint of a
hydraulic hose is determined by the screw
diameter of the hose mouth fitting. When a failure
is found in a hose piping joint, pay attention to
the following points to repair and replace it even
before the periodic inspection of the hydraulic
component unit.
1. Hose
2. Union nut
3. Connector
4. O-ring
A. Crimping surface of O-ring
A
4
4
4
2
3
1
O-RING SEAL JOINT
O-RING PART
1. Be sure to replace the O-ring with a new one at reassembly.
2. If oil leakage occurs due to union loosening, replace the O-ring with a new one instead of
retightening, confirm that it is in contact with the sealing surface properly, and then tighten it.
3. Do not use a new O-ring which has damage or deterioration. Also, it may cause oil leakage or
markedly decrease the service life of the hydraulic components to use an O-ring other than the
specified parts even if it has the same size because the material or hardness can be different.
JOINT PART
1. Be careful not to damage the O-ring groove surface and seal surface of hoses, pipes and other
hydraulic components when connecting them. Using damaged parts causes oil leakage.
2. Be sure to keep out dust or other foreign materials. Foreign materials caught in the joint part
causes oil leakage.
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