Abstract: A pyrotechnic piston and cylinder assembly raises a belt guide, pulling two segments of a safety belt upwardly away from a vehicle seat. The extension of the two segments removes slack from the safety belt. After the piston is fully extended, a pair of wedges jam an inner wall of the cylinder, providing resistance to the retraction of the shaft into the cylinder. As the belt forces overcome the resistance from the wedges, the piston is pushed back into the cylinder and a portion of belt is permitted to extend, relieving tension in the safety belt. The wedges plastically deform the inner wall of the cylinder, thereby absorbing a portion of the energy of the collision.

Abstract: A system (20) for controlling the effective rate at which an air bag (24) is filled comprising: a housing (22) operatively communicated with the air bag such that as the air bag is pressurized by inflation gas such gas enters the housing increasing its internal pressure, the housing (22) including: variable vent (54, 50, 52) for defining an opening through which a quantity of inflation gas is controllably diverted from the air bag to thereby reduce its rate of inflation from that rate which is achieved when the vent means is closed.