Product Code:SAE J2378 Title:Test Procedure for Trailer Air Reservoir Fill and Parking Brake Release Times Issuing Committee:Truck And Bus Brake Systems Committee Scope:This SAE Recommended Practice provides instructions and test procedures for air braked trailers and dollies used in single and multiple trailer combinations on highway. This document is not intended for off-highway application.PurposeThis document provides a method of determining the efficiency of trailer and dolly air supply systems in filling reservoirs and, for those with spring applied parking brakes, in releasing parking brakes.