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Is a warning device required in a Commercial Motor Vehicle (CMV) with a single hydraulic brake system which uses the driveline parking brake as the emergency brake system?

Section § 393.51: Warning signals, air pressure and vacuum gauges.

Guidance Q&A

Question 4: Is a warning device required in a Commercial Motor Vehicle (CMV) with a single hydraulic brake system which uses the driveline parking brake as the emergency brake system?

Guidance: No. Warning devices are not required on such CMVs because the driver will be given ample warning of system failure by the movement and feel of the brake pedal.

Regulatory Topic: Is a warning device required on a hydraulic brake system with driveline parking brake as emergency brake?
Effective Date: Sunday, May 4, 1997
Issued Date: Friday, April 4, 1997