SAE J257-1997 (R)BRAKE RATING HORSEPOWER REQUIREMENTS-COMMERCIAL VEHICLES

Foreword-The 5-year revision of this document addresses only those changes needed for metrification andcompatibility with the revisions of SAE J880, Brakes System Rating Test Code. Also it has been changed to comply with the SAE Technical Standards Board format. No change in the level of recommended performance is intended.
The performance requirements in this SAE Recommended Practice represent the accumulation of the best information available from investigation of the service brake system performance of new motor vehicles designed for roadway use. It reflects the requirements not only of long mountain grades, but also the demands of heavy traffic conditions which impose a relatively higher horsepower duty cycle on the lighter commercial vehicles that accelerate and decelerate more frequently and to higher speeds because of their substantially lower weight-to-horsepower ratio.

1. Scope-The minimum performance values in this SAE Recommended Practice are applicable to vehicles with brake systems having typical service pressure ranges 0 to 14.1 MPa(0 to 2050 psi) hydraulic or 0 to 830 kPa
(0 to 120 psi) air only. SAE J880 not only provides for determining maximum brake rating horsepower capability, but also permits verification of any desired or arbitrary level such as the requirement established herein. The determining criteria for deciding brake rating horsepower capability are:
a. Cold brake stopping ability.
b. Fade as a result of horsepower absorption.
c. Hot brake stopping ability following horsepower absorption.
d. Brake system stability following horsepower absorption.
e. Functional and structural integrity of brake system following test.
1.1 Purpose-The purpose of this document is to establish a minimum Brake Rating Power (BRP) level for commercial vehicles tested in accordance with SAE J880.

2. References
2.1 Applicable Publication-The following publication forms a part of this specification to the extent specified herein. Unless otherwise indicated, the latest issue of SAE publications shall apply.
SAE J880-Brake System Rating Test Code-Commercial Vehicles

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