TUBES AND COMPRESSION FITTINGS
Standard Compression Fittings: Tubes with inverted nuts and compression fittings are designed for
one-time assembly. Once assembled or disassembled, they must be replaced as a unit if any parts are
found defective. Used parts may not seal properly when used with new ones. Used tube assemblies in good
condition can be reinstalled to their original location without leaking. Assemble new tubes, compression
sleeves, and inverted nuts as follows:
Slide inverted nut (Figure 1, Item 2) on end of tube (Figure 1, Item 3).
Slide compression sleeve (Figure 1, Item 1) on end of tube (Figure 1, Item 3).
Repeat Steps a and b for other end of tube as required.
Insert end of tube as far as it will go in compression fitting to which tube is being installed.
Twist inverted nut (Figure 1, Item 2) in compression fitting and tighten inverted nut against
compression sleeve (Figure 1, Item 1) with open-end wrench. Compression sleeve will clamp down
around tube and conform to internal surface of compression fitting and inverted nut.
Repeat Steps d and e for other end of tube as required.
Push-In Fittings: Fittings are used for some of the connections at the spring brake control valve. A push-on
collet collar grips or releases the tubing as required to provide a quick disconnect/ connect feature of the air
line tubing to the fitting, without the use of tools. To separate tubing from fitting, depress the fitting collar until
it bottoms against the fitting and withdraw the tubing. To assemble tubing onto fitting, insert the tubing into
the fitting until it bottoms, pushing on tubing twice to verify that tubing is inserted past collet and O-ring. Pull
fitting collar out to lock tubing and pull on tubing to verify it is locked in place. Tubing cut for insertion into the
fitting must be squarely cut. The maximum allowable angle is 15 degrees. Use of a tube cutting tool
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