Volvo 2005 S80 Operation And Care Manual page 6

To buckle:
Pull the belt out far enough to insert the latch plate into the receptacle until a distinct click is heard. The seat belt
retractor is normally "unlocked" and you can move freely, provided that the shoulder belt is not pulled out too far. The
retractor will lock up as follows:
if the belt is pulled out rapidly
during braking and acceleration
if the vehicle is leaning excessively
when driving in turns
For the seat belt to provide maximum protection in the event of an accident, it must be worn correctly. When wearing
the seat belt remember:
The belt should not be twisted or turned.
The lap belt must be positioned low on the hips (not pressing against the abdomen).
Make sure that the shoulder belt is rolled up into its retractor and that the shoulder and lap belts are taut.
The seat belts are equipped with tensioners that reduce slack in the seat belts. These tensioners are triggered in
situations where the airbags deploy.
The front seat belts also include a tension reducing device which, in the event of a collision, limits the peak forces
exerted by the seat belt on the occupant.
Before exiting the car, check that the seat belt retracts fully after being unbuckled.
If necessary, guide the belt back into the retractor slot.
NOTE: Legislation in your state or province may mandate seat belt usage.
Child seats: Please refer to
Adjusting shoulder belt
Lap portion of the belt should sit low
page 16 for information on securing child seats with the seat belts.