DOT Air Brake Fittings for Trucks, Trailers, and Heavy-Duty Vehicles

Air Brake Fittings for Trucks and Trailers

Air brake systems on trucks, trailers, and heavy-duty vehicles depend on certified fittings to keep the lines pressurized, sealed, and safe. When a brass D.O.T. fitting fails or a nylon tube splits, the repair must be done using the same regulated components as the original assembly. Substituting a generic pneumatic fitting is not legal under CMVSS 106 (Canada) or FMVSS 106 (United States).

Cleanflow stocks the Greenline range of pre-packaged air brake repair kits, each housed in a heavy-duty carry case. The right fitting, sleeve, mender, or adapter is on hand when a line needs to come apart in the field or at the shop.

Types of Air Brake Fittings: Which One Fits Your Repair

Air brake fittings are not interchangeable. The fitting type must match the line type and the assembly method specified by the OEM. Use this guide to identify the right fitting family for your repair:

Compression fittings (for copper or coated steel tubing)

Compression fittings use a threaded nut, a sleeve (or ferrule), and an insert to seal against the outside of a tubing run. Two compression sub-types are common in air brake work: tapered sleeve compression (SAE J512) and spherical/flanged sleeve compression (SAE J246, intended for annealed copper alloy tubing per SAE J1149). The Greenline Brass D.O.T. Air Brake Fittings Kit for General Repairs is the all-purpose compression kit — male pipe (NPT) compression connectors and 90° elbows, plain air brake nuts, nuts with springs, sleeves, inserts, bulkhead couplings, and unions in the most common truck and trailer sizes.

Push-to-connect fittings (for nylon air brake tubing)

Push-to-connect fittings use an internal collet that grips the outside of nylon tubing when the tube is pushed into the fitting body. No nut, sleeve, or insert is needed. SAE J1131. sets the performance requirements for these fittings. They are designed for use with SAE J844 nylon air brake tubing, which is rated for 150 psi service and operates from −40°F to 200°F. The Greenline Brass D.O.T. Kit for Nylon Tube Repairs covers the push-to-connect range push-to-connect unions in 1/4", 3/8", and 1/2", male pipe (NPT) × push-to-connect connectors and 90° elbows in matching sizes, plus three 8" lengths each of 1/4", 3/8", and 1/2" nylon tubing and a thumb knife for clean perpendicular cuts.

Hose menders and swivel fittings (for rubber air brake hose)

Rubber air brake hose (SAE J1402) uses crimped or threaded end fittings, rather than reusable compression or push-to-connect fittings. When a section of rubber hose fails mid-run, hose menders splice two cut ends back together, and female swivel air brake fittings reconnect the hose to a chamber port or gladhand. The Greenline Brass D.O.T. Kit for Rubber Air Brake Hose Repairs includes menders and female swivels in 3/8" and 1/2", brass bushings (3/8" × 1/4", 1/2" × 3/8"), and male pipe (NPT) × air brake adapters in 1/4", 3/8", and 1/2" sizes.

Threaded NPT adapters and bushings

Most air brake repairs eventually need an NPT-threaded adapter, a male pipe thread on one side, a compression or push-to-connect or air brake thread on the other. All three Greenline kits include NPT adapters and bushings to bridge between line types and chamber/valve ports. For dedicated NPT-only inventory beyond the kits, special order from Cleanflow.

DOT Compliance: What Every Fleet Maintainer Should Know

CMVSS 106 (Canada) and FMVSS 106 (United States)

Air brake hose, tubing, and fittings sold for on-road use in Canada must meet Canada Motor Vehicle Safety Standard 106 (CMVSS 106), administered by Transport Canada. The US equivalent is Federal Motor Vehicle Safety Standard 106 (FMVSS 106) under 49 CFR 571.106, administered by NHTSA.

The two standards are largely harmonized in practice. A properly DOT-stamped fitting that conforms to FMVSS 106 will also satisfy CMVSS 106 requirements for cross-border fleet operations. The standards govern labelling, burst pressure, whip resistance, cold flexibility (down to −49°F), salt spray corrosion, and fitting-to-tubing retention. "DOT" stamped on the fitting body certifies the manufacturer has registered with the Department of Transportation and that the part meets the applicable safety standard.

SAE standards referenced by CMVSS / FMVSS 106

CMVSS 106 and FMVSS 106 incorporate several SAE technical standards by reference. The ones that matter most for air brake fittings:

SAE J844 — Non-metallic air brake tubing (nylon). Type A is non-reinforced, and Type B is reinforced. Rated for 150 psi service.
SAE J1131 — Performance requirements for reusable (push-to-connect) fittings used in automotive air brake systems. Covers tube retention, leak resistance, and temperature cycling.
SAE J1149 — Annealed copper alloy tubing for use with spherical and flanged sleeve compression fittings.
SAE J246 — Spherical and flanged sleeve (compression) tube fittings for air brake piping.
SAE J1402 — Rubber air brake hose, crimp-end and reusable-end assemblies.

Why do aftermarket fittings need certification?

The CMVSS / FMVSS 106 burst pressure test runs to 4,000 psi for two minutes without rupture. Whip testing flexes the assembly for 35 hours under pressure. Cold resistance testing chills the fitting below −49°F for 70 hours and inspects for cracking. Standard pneumatic fittings, even brass ones rated to high pressure, are not tested to these requirements and must not be used as substitutes in an on-road air brake assembly. Greenline D.O.T. fittings carry the manufacturer's DOT registration symbol and are built to the CMVSS / FMVSS 106 fitting performance requirements.

About Greenline

Greenline manufactures hoses, fittings, adapters, couplings, and accessories for industrial, commercial, and automotive applications across agriculture, construction, manufacturing, and trucking. The company's brass D.O.T. air brake fittings are built to the CMVSS / FMVSS 106 fitting requirements and are packaged into pre-assembled repair kits for fleet shop and roadside use.

Best-Selling Air Brake Fittings Products

Discover some of our most popular air brake fittings designed for maximum performance and reliability:

Brass D.O.T. Air Brake Fittings Kit for General Repairs

Brass D.O.T. Air Brake Fittings Kit for General Repairs is a comprehensive solution for addressing air brake line malfunctions in trucks and trailers, whether in the field or the shop. The kit is housed in a heavy-duty carry case. It includes a range of brass D.O.T. fittings, such as air brake hose menders, sleeves, plain air brake nuts, male pipe inserts, air brake nuts with springs, bulkhead couplings, compression sleeves and nuts, compression inserts, compression unions, male pipe compression connectors, and male pipe compression 90° elbows. The kit also contains Teflon tape.

Brass D.O.T. Air Brake Fittings Kit for Nylon Tube Repairs

Brass D.O.T. Air Brake Fittings Kit for Nylon Tube Repairs is designed for use in the field or shop to address malfunctions in truck and trailer air brake nylon tubing. Housed in a heavy-duty carry case, this kit includes: three 8" lengths each of 1/4", 3/8", and 1/2" nylon air brake tubing; push-to-connect unions in 1/4", 3/8", and 1/2" sizes; male pipe (NPT) x push-to-connect connectors and 90° elbows in various sizes; and a thumb knife. This comprehensive kit facilitates quick and effective repairs of nylon air brake lines.

Brass D.O.T. Air Brake Fittings Kit for Rubber Air Brake Hose Repairs

Brass D.O.T. Air Brake Fittings Kit for Rubber Air Brake Hose Repairs is a comprehensive kit to address truck and trailer rubber air brake hose malfunctions. The kit is housed in a heavy-duty carry case. It contains: two 8" lengths of 3/8" air brake hose, two 8" lengths of 1/2" air brake hose, a 3/8" air brake hose mender, a 1/2" air brake hose mender, a 3/8" female swivel air brake fitting, a 1/2" female swivel air brake fitting, two 3/8" x 1/4" brass bushings, two 1/2" x 3/8" brass bushings, two 1/4" male pipe (NPT) x 3/8" air brake adapters, two 3/8" male pipe (NPT) x 3/8" air brake adapters, two 3/8" male pipe (NPT) x 1/2" air brake adapters, two 1/2" male pipe (NPT) x 1/2" air brake adapters, Teflon tape, and a thumb knife.

Buy DOT Air Brake Fittings Online from Cleanflow

Cleanflow stocks Greenline brass D.O.T. air brake fitting kits, general repair, nylon tube repair, and rubber hose repair for fleet shops, mobile mechanics, and owner-operators across Canada. Browse the kits above, or call 1-866-335-1078 for sizing help, fleet quotes, or special orders on Greenline air brake fittings not currently stocked online.

FAQs

1. What are air brake fittings used for?

Air brake fittings connect and secure air brake lines, tubing, and hoses on trucks, trailers, and heavy-duty vehicles, maintaining pressurized airflow for proper brake operation. Fittings used on the road in Canada must meet CMVSS 106 (FMVSS 106 in the US) and carry the DOT certification stamp.

2. What types of air brake fittings are available?

Air brake fittings come in various types, including push-to-connect, compression, and threaded fittings, made from durable materials like brass and composite.

3. Are these fittings compatible with all air brake systems?

Greenline brass D.O.T. fittings are sized for the most common air brake line ODs 1/4", 3/8", and 1/2" and are compatible with standard truck, trailer, and bus air brake systems built to CMVSS / FMVSS 106. Always confirm the line OD, the line type (nylon, copper, rubber), and the fitting style (compression, push-to-connect, threaded) before ordering.

4. How do I install air brake fittings?

Installation depends on the type of fitting. Push-to-connect fittings require inserting the hose into the fitting until it locks, while compression and threaded fittings may require tightening with tools. Always follow manufacturer guidelines.

5. How do I ensure a secure and leak-free connection?

Use appropriately sized fittings and ensure the airlines are cut cleanly and inserted correctly. Regularly inspect connections for wear or leaks and replace any damaged fittings promptly.

6. Are brass or composite fittings better?

Both materials have advantages. Brass fittings offer superior durability and resistance to high temperatures, while composite fittings are lightweight and corrosion-resistant. The choice depends on your specific application.

7. How often should air brake fittings be inspected or replaced?

Inspect air brake fittings during every routine vehicle maintenance interval and as part of any pre-trip inspection. Replace any fitting showing leaks, cracks, corrosion, or thread damage. In Canada, commercial vehicles are subject to provincial CVIP (Commercial Vehicle Inspection Program) requirements, and air brake assembly defects are common reasons for an out-of-service order.

8. Are nylon tube push-to-connect fittings DOT-approved?

Yes, push-to-connect fittings designed for SAE J844 nylon air brake tubing must meet SAE J1131 performance requirements (tube retention, leak resistance, temperature cycling) to qualify as DOT/CMVSS 106 compliant. The Greenline Brass D.O.T. Kit for Nylon Tube Repairs includes push-to-connect unions, connectors, and elbows that meet these requirements. Look for the DOT stamp on the fitting body to confirm compliance.

9. Where to buy DOT air brake fittings in Canada?

Cleanflow ships Greenline brass D.O.T. air brake fitting kits from our Winnipeg warehouse to addresses across Canada. Most prairie and Ontario orders arrive in 1–3 business days; Quebec, Atlantic Canada, and BC in 3–5 business days. Free courier shipping applies to orders over $199. For volume or fleet pricing on multiple kits, contact our team at 1-866-335-1078.

Upgrade your air brake system with high-quality fittings from Cleanflow—explore our collection today for the best in safety and performance!