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Safety alert: Trailer brake interlock safety systems

ATA subcommittee the Industry Technical Council has created a safety alert on possible dangers relating to trailer brake interlock safety systems


The issue or incident:

Some brake interlock systems designed to prevent the vehicle moving during loading/unloading may have the potential to apply the emergency brakes when the vehicle is moving at speed. The emergency brake circuit of a commercial vehicle does not include any ABS or other control system functionality, which could result in wheel locking, creating a dangerous situation. This problem may arise if an element in the interlock system comes loose or fails when the vehicle is in motion.


The use of a No Air In Motion (NAIM) interlock system will prevent vehicles moving while the interlock is active loading/unloading, but not result in interlock activation when already moving.