Seat belt for placing around vehicle occupant

The belt incorporates a housing connectable to a vehicle component and a flexible member with first and second end parts and intermediate part. The intermediate part extends between the first and second end parts and a part of it is located in the housing, in conjunction with which it works in order to define an expandable chamber in the housing. The housing has surface device for guiding a movement of the part of the intermediate part along an arc-shaped path for expansion of the expandable chamber. A coupling is operable in response to the expansion of the expandable chamber in order to connect the first end part with the seat belt. Operable devices after operation exert a first force on the part of the intermediate part, in order to move the part of the intermediate part along the arc-shape path in the housing for expansion of the expandable chamber, in order to operate the coupling to move the first part of the flexible member in a direction causing the seat belt (20) to move through a first distance, drawing it firmly against the vehicle occupant. A length of the seat belt is expandable around the occupant, and one end of it is anchored (28) in the vehicle body (26) on one side of the seat (24). The opposing end of the belt is fitted to a drawback device (22).