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Electric motor driven reel in operation

When the driver or front passenger fastens their seat belt or there is a critical driving situation in terms of driving dynamics, the electric motor is activated and moves the drive shaft using the worm gear.

The worm gear turns the drive wheel with the coupling. The locking pawls move out and engage in the ring gear (C).

The ring gear, which is located on the belt shaft, drives the belt shaft (D). The seat belt is rolled up on the belt shaft and thereby shortened. This tensions the seat belt to the occupants.

Fig 1: Identifying Locking Pawls Movement And Ring Gear Turning Belt Shaft
G06925581Courtesy of BMW OF NORTH AMERICA, INC.