Brake power assist unit.

Brake power assist unit. A device installed in a hydraulic brake system that reduces the operator effort required to actuate the system, but which if inoperative does not prevent the operator from braking the vehicle by a continued application of muscular force on the service brake control.

Source

49 CFR § 393.5


Scoping language

As used in this part, the following words and terms are construed to mean:

Is this correct? or