Air Bag And Safety Belt PRETENSIONER Supplemental Restraint System (SRS): PRETENSIONERS
| Item Number | Description |
|---|---|
| 1 | Safety belt buckle |
| 2 | Boot |
| 3 | Anchor bolt |
| 4 | Piston and tube |
| 5 | Electrical connectors for inflator and buckle switch |
The pretensioners are used to tighten the front safety belts during a collision to ensure the occupants are securely held in their seats. A pretensioner is integrated into each front safety belt buckle.
Each pretensioner has a tube containing an inflator and a piston. The inflator is connected to the restraints control module (RCM). The piston is attached to a steel cable, the opposite end of which is attached to the safety belt buckle.
On receipt of a fire signal from the restraints control module (RCM), the inflator generates nitrogen gas that rapidly expands to drive the piston along the tube, pulling the cable and drawing the safety belt buckle downwards.