# Federal Motor Vehicle Safety Standards; Air Brake Systems
> **National Highway Traffic Safety Administration** · Final rule; technical amendment. · Published 2002-05-28 · Effective 2002-06-27 · 67 FR 36819
## Document
- **Document number:** 02-13221
- **Category:** fmvss
- **Sub-agency:** National Highway Traffic Safety Administration
- **Federal Register citation:** 67 FR 36819
- **CFR reference:** 49 CFR 571
- **Publication date:** 2002-05-28
- **Effective date:** 2002-06-27
- **DOT docket:** Docket No. NHTSA-02-12053
## Abstract

In a May 3, 1989 final rule, NHTSA changed the brake applications and release timing requirements of the Federal motor vehicle safety standard on air brake systems. The changes to these requirements resulted in the addition of a new schematic diagram of a trailer test rig, labeled as Figure 1, to the standard. A pre-existing trailer test rig schematic was re-labeled as Figure 1(a) and retained for use until the new brake application and release timing requirements and the new figure became effective May 3, 1991. We are now deleting the obsolete Figure (1)(a). A provision describing the pressure characteristics of the trailer test rig depicted in Figure 1(a) is also being deleted. We are also taking this opportunity to correct various minor errors and omissions in the standard.

## Source
- [Federal Register document](https://www.federalregister.gov/documents/2002/05/28/02-13221/federal-motor-vehicle-safety-standards-air-brake-systems)
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