The tensioner is equipped with an inertial mechanism that is triggered when the frontal overloads exceed a certain value. Weaker impacts do not trigger the device.
When the mechanism is turned on, the fuel placed inside the device is ignited. In this case, the piston of the assembly moves forward sharply, choosing the slack of the belt, which at the same time is wound onto the inertial drum of the return device. The energy of the explosion occurring in the tensioner cylinder guarantees a secure fixation of the passenger by the seat belt. After actuation, the tensioner is irreversibly blocked and cannot be reused.
Some special precautions must be observed when performing maintenance on front seat belts equipped with pretensioners:
Attention!
- If you accidentally drop the tensioner, it must be replaced regardless of its external condition.
- Do not allow solvents to come into contact with the components of the tensioner mechanism!
- Try not to hit the car body in the area of the tensioners during the body work!
- Do not allow the tensioner assembly to heat up to temperatures above 100°C!