Abstract: An automatic seat belt system, having; a guide rail disposed in a room of a vehicle, a slider engaged with one end of a webbing for restraining an occupant of the vehicle and guide by the guide rail in a manner capable of moving therealong between a webbing-application canceling position and a webbing applying position, and a slider retaining member which engages with the slider and retains thereof at the webbing applying position and which enables to alter the retaining position while retaining the slider.

Abstract: A buckle apparatus for use in a seatbelt system is arranged such that when a tongue plate is inserted into a buckle body, the tongue plate retaining portion of a lock plate pivotally supported on one side of the tongue plate insertion passage extends through an opening formed in the tongue plate and projects out to the other side of the insertion passage so as to engage with a subsidiary lock plate. Accordingly, the lock plate which prevents the tongue plate from being undesirably pulled out is supported by the buckle body on both sides of the tongue plate and therefore can bear a large load. To release the tongue plate, the subsidiary lock plate is pivoted so as to disengage from the lock plate, which requires only a reduced force.

Abstract: A buckle apparatus for use in a seatbelt system is arranged such that when the tongue plate of the seatbelt is inserted into the buckle body, the pawl of a lock plate is inserted into an opening formed in the tongue plate. Since the projecting end of the pawl is separated from the corresponding opening formed in the buckle body, a relatively small force can release the tongue plate from the buckle apparatus. However, when the force applied to the tongue plate for pulling it out from the buckle apparatus increases, a lock plate holder is deformed by virtue of this force. In consequence, the pawl engages with the opening of the buckle body, and retaining wings provided on the side of the lock plate remote from the pawl also engage with the corresponding portions of the buckle body. Accordingly, the lock plate is supported by the buckle body at two portions on both sides of the portion thereof which engages with the tongue plate, so that the lock plate can bear a large tongue plate pulling out force.