OOSC, Part II, Item 1. Brake System, c. Parking Brakes

This subsection appears to be titled incorrectly. Subsection c.(1) addresses breakaway braking systems on trailers and cites 393.43(d) as a reference, which specifically addresses the requirement for a breakaway system on trailers. Technically, this Subsection has nothing to do with Parking Brakes required by 393.41. In some cases, the breakaway system and parking brake system on some trucks are combined. However, CMV buses are not required to have a similar system that actuates when low air pressure is attained.

A clarification should be issued immediately to address this issue. Specifically, that a breakaway system required by 393.43(d) should not be considered a \"parking brake\" and is not specifically required on passenger carrying CMVs. CMV buses are not specifically required to have a braking system that activates automatically when low air pressure is attained. In fact 393.41(b) requires that a parking brake system be separate from other brake application systems, operated manually and be capable of holding a CMV under any condition of loading (FMVSS 571.121 S5.6) even when all other systems have low air. Currently no inspection criteria exists to determine the effectiveness of a CMVs parking brake system nor to place a vehicle OOS for an inoperative parking brake system on either CMV trucks or buses. It seems appropriate to consider and develop inspection criteria and OOS criteria for trucks and buses whose parking brakes do not hold the vehicle in position under any circumstance of loading. A CMV whose parking brake is inoperative could certainly lead to a crash.

A system for inspection should be researched and developed to determine the adequacy of parking brake systems on CMV trucks and buses. Likewise, criteria for "out-of-service" should be established whereby a CMV truck or bus is no longer allowed to operate should its parking brake system be defective. Subsection c. Parking Brakes should be re-titled as "Breakaway Systems" or something similar. Furthermore, a new subsection, titled Parking Brakes should be added referring specifically to 393.41 and FMVSS 571.121. Subsection c.(2), referring to non-manufactured holes in the spring brake should be duplicated and added to the new Parking Brake subsection.