The 1974 Toyota Belt Interlock System

Various types of belt systems with emergency locking retractors (ELR) have been developed and evaluated for their efficiency and comfort. The optimum belt system in combination with the starter interlock system is considered to be the three-point belt system with separate lap and shoulder electromagnetic ELR.

We have developed a reliable and comfortable OFF-lock type retractor by incorporating a locking release mechanism that will operate when a predetermined length of belt is pulled out. This device is small enough to be embedded in the roof side structure of a vehicle by using narrower webbing (24 mm) and an electrical locking retractor which is smaller than the conventional mechanical type.

The electromagnetic ELR system, combined with a mercury g sensor, was tested and evaluated for locking time, comfort, and injury criteria, as well the strength of the narrow webbing.