Application of FMVSS 206 Inertial Force Requirement to Step Van Latch Hardware

The analysis presented demonstrates the application of section 5.1.1.4 (a) Inertial Force Calculation of the Federal Motor Vehicle Safety Standard 206 (FMVSS 206) to a step van pocket sliding door latch system. FMVSS 206 applies to step van trucks regardless of the gross vehicle weight rating (GVWR) as clarified by the National Highway Traffic Safety Administration (NHTSA). The step van latching system is a unique latch configuration with a floating pivot that enables the latch to engage the striker plates at both the open and closed body pillars for latching closed and holding open. The latch forkbolt bar can be actuated in both unlatching directions with the same handle. FMVSS 206 specifies a minimum inertial resistance requirement for the latch system to ensure the latched state is maintained when acted upon by inertial force generated during an impact event. This calculation method follows the approach recommended in SAE J839 for a door latching system. Two calculation analysis approaches are covered in this article. Utilizing a spreadsheet, both approaches can be used to determine the minimum inertial force threshold for the system in each of the four federally required impact directions. While this article only covers the inertial force calculation (also known as 30g) portion of the FVMSS 206, it should be noted that the hardware set also presents uniqueness for the hardware load test portion of the regulation in terms of how the hardware is set up for the test. FMVSS 206 compliance requires a system approach beyond the 30g requirements since the door integration and latch striker execution are an integral part of the performance.