• Title 49 Part 571.121 -- Air Brake Systems
• Title 49 Part 393.40 -- Required Systems
• Title 49 Part 393.43 -- Breakaway & Emergency
• Title 49 Part 393.45-46 -- Brake Tubing
• Title 49 Part 393.50 -- Reservoirs
• Title 49 Part 393.55 -- Anti-Lock Brakes

• Title 49 Part 571 Section 106

• Title 49 Part 571.108 -- Lamps, Reflective Devices, And Associated Equipment
• Title 49 Part 393.11 -- Lights & Reflectors
• Title 49 Part 393.19 -- Turn Signals

(a) General requirements. Brake tubing and brake hose must--

(1) Be designed and constructed in a manner that insures proper, adequate, and continued functioning of the tubing or hose;

(2) Be installed in a manner that insures proper continued functioning of the tubing or hose;

(3) Be long and flexible enough to accommodate without damage all normal motions of the parts to which it is attached;

(4) Be suitably secured against chafing, kinking, or other mechanical damage;

(5) Be installed in a manner that prevents it from contacting the vehicle's exhaust system or any other source of high temperatures; and

(6) Conform to the applicable requirements of paragraph (b) or (c) of this section.

In addition, all hose installed on and after January 1, 1981, must conform to those applicable subsections of FMVSS 106 (49 CFR 571.106).

(b) Special requirements for metallic brake tubing, nonmetallic brake tubing, coiled nonmetallic brake tubing and brake hose.

(1) Metallic brake tubing, nonmetallic brake tubing, coiled nonmetallic brake tubing, and brake hose installed on a commercial motor vehicle on and after March 7, 1989, must meet or exceed one of the following specifications set forth in the SAE Handbook, 1985 edition:

(i) Metallic Air Brake Tubing--SAE Recommended Practice J1149-- Metallic Air Brake System Tubing and Pipe--July 76.

(ii) Nonmetallic Air Brake Tubing--SAE Recommended Practice J844-- Nonmetallic Air Brake System Type B--OCT 80.

(iii) Air Brake Hose--SAE Recommended Practice J1402--Automotive Air Brake Hose and Hose Assemblies--JUN 85.

(iv) Hydraulic Brake Hose--SAE Recommended Practice J1401 Road Vehicle-Hydraulic Brake Hose Assemblies for Use with Non-Petroleum Base Hydraulic Fluid JUN 85.

(v) Vacuum Brake Hose--SAE Recommended Practice J1403 Vacuum Brake Hose JUN 85.

(2) Except as provided in paragraph (c) of this section, brake hose and brake tubing installed on a motor vehicle before March 7, 1989, must conform to 49 CFR 393.45 effective October 31, 1983.

(c) Nonmetallic brake tubing. Coiled nonmetallic brake tubing may be used for connections between towed and towing vehicles or between the frame of a towed vehicle and the unsprung subframe of an adjustable axle of that vehicle if--

(1) The coiled tubing has a straight segment (pigtail) at each end that is at least 2 inches in length and is encased in a spring guard or similar device which prevents the tubing from kinking at the fitting at which it is attached to the vehicle; and

(2) The spring guard or similar device has at least 2 inches of closed coils or similar surface at its interface with the fitting and extends at least 1\1/2\ inches into the coiled segment of the tubing from its straight segment.

(d) Brake tubing and brake hose, uses. Metallic and nonmetallic brake tubing is intended for use in areas of the brake system where relative movement in the line is not anticipated. Brake hose and coiled nonmetallic brake tubing is intended for use in the brake system where substantial relative movement in the line is anticipated or the hose/ coiled nonmetallic brake tubing is exposed to potential tension or impact such as between the frame and axle in a conventional type suspension system (axle attached to frame by suspension system). Nonmetallic brake tubing may be used through an articulation point provided movement is less than 4.5 degrees in a vertical plane, and 7.4 degrees in a transverse horizontal plane.

All connections for air, vacuum, or hydraulic braking systems shall:

(a) Be adequate in material and construction to insure proper continued functioning;

(b) Be designed, constructed, and installed so as to insure, when properly connected, an attachment free of leaks, constrictions, or other defects;

(c) Have suitable provision in every detachable connection to afford reasonable assurance against accidental disconnection;

(d) Have the vacuum brake engine manifold connection at least three- eighths inch in diameter.

(e) If installed on a vehicle on or after January 1, 1981, meet requirements under applicable subsections of FMVSS 106 (49 CFR 571.106).

(f) Splices in tubing if installed on a vehicle after March 7, 1989, must use fittings that meet the requirements of SAE Standard J512-OCT 80 Automotive Tube Fittings or for air brake systems SAE J246--March 81 Spherical and Flanged Sleeve (Compression) Tube Fittings as found in the SAE Handbook 1985 edition.