Service maintenance and repair of trucks in a large garage.

In the heavy truck aftermarket sometimes mechanics will use hydraulic hose for air brake applications because they are rated at a much higher pressure than air brake hose. Yet this is not necessarily safer and air brake hose assemblies must meet specific D.O.T. requirements that specify adequate working pressure to assure consistent safety across a variety of heavy truck applications. For vehicles operating on public roads and highways air brake systems must pass a series of tests prescribed by the National Highway Traffic Safety Administration (NHTSA) to meet the required D.O.T approval. The most popular pre-assembled D.O.T. rubber air brake assemblies are:

• Available in various hose lengths, typically from 14” to 96”
• Preassembled with brass fitting connections:
• 3/8 I.D. Hose C/W 1/4 MPT Swivel x 1/4 MPT Fixed
• 3/8 I.D. Hose C/W 1/4 MPT Swivel x 1/4 MPT Swivel
• 3/8 I.D. Hose C/W 3/8 MPT Swivel x 3/8 MPT Fixed
• 3/8 I.D. Hose C/W 3/8 MPT Swivel x 3/8 MPT Swivel
• 1/2 I.D. Hose C/W 1/2 Female Flare Swivel on Both Ends
• 1/2 I.D. Hose C/W 3/8 MPT Swivel x 3/8 MPT Fixed
• 1/2 I.D. Hose C/W 3/8 MPT Swivel x 3/8 MPT Swivel

• Grease Whip Assemblies – SAE100R1 Hose:
• Available in lengths from 8” to 36”
• 3/16 x 1/8 MPT Both Ends

D.O.T. Reusable Air Brake Hose Fittings

Reusable air brake hose fittings which meet D.O.T specifications incorporate hose ends that attach hoses to other components of the air brake assemblies and have the following specifications and features & benefits:

  • Brass body material capable of withstanding -40°F to +120°F (-40°C to +48°C)
  • Features & Benefits: Used for virtually any air brake hose line and ease of assembly with proper selection of hose ends. Provides excellent corrosion
  • Male pipe thread
  • Meets SAE & D.O.T. specifications, D.O.T. H3380 for brass fittings
  • Specified up to 125 PSI as determined by maximum working pressure of the hose size

D.O.T. Rubber Air Brake Assemblies

Hose assemblies for air brakes must be clearly marked “D.O.T.” on the hose layline and on all fittings.

To be in compliance and to legally run your vehicle on the roadways it is necessary the air brake hoses are tested to perform in many different conditions which occur on and around the vehicle’s air brake systems, which includes more than just pressure ratings.  The list below reflects test areas that D.O.T. air brake hoses must pass in order to obtain approval:

  • Adhesion
  • Change in lengths
  • Construction
  • Corrosion resistance and burst strength
  • Fitting corrosion resistance
  • Flex strength and pressure cycling
  • Internal clearance
  • Oil resistance
  • Ozone resistance
  • Resistance to cold temperature
  • Resistance to high temperatures
  • Resistance to zinc chloride
  • Tensile strength
  • Tensile strength during water absorption

All D.O.T. approved hose and fittings have the D.O.T. designation on the product.

This blog is an excerpt of our whitepaper, DOT Fittings For Truck & Trailer applications. If you’d like to learn more, click here or below to download the full whitepaper.

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