§383.95 Air Brake Restrictions

Question 1: A driver has a Group B or C CDL valid for airbrake- equipped vehicles. He or she later upgrades to a Group A license by testing in a vehicle that is not equipped with airbrakes. Must the State restrict the upgraded license to nonairbrake-equipped vehicles?

Guidance: No, because the airbrake systems on combination versus single vehicles do not differ significantly.

Question 2: May a driver who has an air brake restriction as defined in §383.95 operate a CMV equipped with an air-over- hydraulic brake system?

Guidance: No. Under §383.95(b), the term "air brakes" includes any braking system operating fully or partially on the air brake principle. Air-over-hydraulic brake systems operate partially on the air brake principle and are therefore air brakes for purposes of the CDL regulations. The NHTSA also considers "air over hydraulic" brakes to be air brakes under FMVSS 121.

Question 3: May a State issue a restriction to a driver who passes the air brake knowledge test and the skills test in a vehicle equipped with an air-over-hydraulic brake system that limits the driver to operate only vehicles equipped with an air-over-hydraulic air brake system?

Guidance: Yes. A State may issue the additional restriction, provided it is fully explained on the CDL. This would give a State the option to allow a driver who tests in a vehicle equipped with an air- over-hydraulic brake system (rather than a full air brake system) to operate a vehicle equipped with either a hydraulic or air-over- hydraulic brake system, while restricting them from operating vehicles equipped with a full air brake system.

Question 4: May a driver with an air brake restriction on his or her CDL operate a CMV equipped with a hydraulic braking system that has an air-assisted parking brake release?

Guidance: Yes. The air brake restriction applies only to the principal braking system used to stop the vehicle. §383.95(b) is not applicable to an air-assisted mechanism to release the parking brake.