A seat belt buckle having a buckle frame and a pivotal latching member mounted therein includes a single spring for biasing a push button toward an outer position and for ejecting a tongue plate from the frame when the latch mechanism is in its open position. The preferred spring is a coil spring which is loaded in tension in an extended configuration. In the preferred embodiment, the spring additionally provides biasing force to lock the latch mechanism in its latching position after insertion of the tongue plate into the buckle frame and provide biasing force to maintain the latching member in its open position prior to insertion of the tongue plate.
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