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Is the vacuum portion of vacuum-assisted hydraulic brake systems required to have a warning device?

April 26, 2017Brake device hydraulic portion SYSTEMS vacuum vacuum-assisted warning

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Is the vacuum portion of vacuum-assisted hydraulic brake systems required to have a warning device?

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Guidance: No. Only the hydraulic portion of vacuum-assisted hydraulic brake systems is required to have a warning device. FMVSS No. 105 does not require a warning device for the vacuum portion of the vacuum-assisted hydraulic brake systems. It is the intention of the FHWA that §393.51 be consistent with FMVSS No. 105. Question 3: Are vacuum gauges required on the vacuum portion of vacuum-assisted hydraulic brakes? Guidance: No. §393.51(d)(2) requires only that CMVs with vacuum brakes (not hydraulic brakes applied or assisted by vacuum) be equipped with a vacuum gauge. Question 4: Is a warning device required in a 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. Question 5: What difference, if any, is there between a warning device and a warning signal? Guida