Vehicle Brake Balance Using Objective Brake Factors

Harmonization of passenger car brake regulations FMVSS 105 and ECE R13 has been pursued for more than eight years. Among the challenges facing this effort are the distinct characteristics of self certification and type approval regulatory protocols, and the differing emphasis of the two existing regulation, i.e., FMVSS 105 focuses on stopping distances while ECE R13 has vehicle brake balance as a primary thrust. Most recently the principal interest of the harmonization effort has been to identify a single method for the certification of vehicle brake balance suitable for use in both self certification and type approval environments.

A test procedure and analysis protocol based on torque wheel tests of individual specimen vehicles has been developed and demonstrated to be both objective and practicable for certification purposes. This method for determining objective brake factors (OBF) offers significant advantages over several other proposals including preserving the form of the current brake balance regulatory provisions of Annex 10 of ECE R13, an independence from prevailing tire, road, and driver influences, and a rational means for dealing with the inevitable stop to stop variability in vehicle brake balance.