SAE J2923_202412

The SAE J2923 procedure is a recommended practice that applies to on-road vehicles with a GVWR below 4540 kg equipped with disc brakes. This SAE Recommended Practice is the result of an industry effort to develop inertia dynamometer test procedures to assess brake drag under a series of test schedules based on the desired application. The test allows the project or application engineer to determine or compare the amount of brake drag for a given design level or configuration. The test provides a standard method to better quantify and better understand the parasitic (drag) torque generated by the brake corner during off brake condition under repeatable laboratory conditions. This inertia dynamometer test procedure provides four methods to quantify brake drag measurements combining light, moderate, and severe braking with a brake drag matrix. This matrix combines increasing static preconditioning pressure applications before measuring brake drag with expanded braking speeds. This test features four schedules focused on providing the user the option to perform drag evaluation specific to its purposes, and it now also includes a way to test electromechanical brakes (EMB) and brake configurations used on electric or hybrid vehicles. Data from either of these four schedules is useful to assess the influence of certain design features, determine brake sensitivity to braking speeds, and conditioning. Elements from this recommended practice are also applicable or useful for other laboratory test procedures to assess brake drag. Due to the novelty of this SAE Recommended Practice, especially with the introduction of the WLTP brake cycle, the Task Force encourages users of this document to contact the SAE Staff Representative for the Foundation Brake Steering Committee or the Chairman of the Brake Dynamometer Standards Committee with questions and comments. This feedback will provide valuable for future revisions and updates. This SAE Recommended Practice is intended as a guide toward standard practices and is subject to change to keep pace with experience and technical advances.