Audi Q7 2017 Manual page 17

Because the safety belt is connected to the belt retractor
shaft (6), the belt is retracted and tensioned.
To help ensure the belt force exerted on the occupants
stays within a defined range, it is limited by the retractor
shaft (6) which is a torsion bar spring. The "Snake" (5) is
moved to the side by the guide (8) in a controlled manner.
The distance which the piston (2) travels is limited by the
stopper which moves up against the braking wedge (4).
When the stopper (2) has reached the end of its travel, the
long part of the "Snake" (5) protrudes a defined distance
from the guide tube/pressure chamber (3). At this point,
four short parts of the "Snake" come into contact with the
gear (7). Due to the five-piece design of the "Snake", the
four short parts displace and push the "Snake" in such a
way that the gear and the retractor shaft (6) are again free.
The belt tensioning process is now complete.
Piston (2)
Braking
wedge (4)
"Snake" (5)
Retractor
shaft (6)
Guide (8)
637_103
Piston with
stopper (2)
Guide tube/pres-
sure chamber (3)
"Snake" (5)
Retractor
shaft (6)
Gear (7)
637_104
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