Safety belt buckles

A tongue and buckle fastener for a safety belt comprising a tongue having a latching formation thereon, and a buckle comprising a body in which a pssageway is provided for receiving the tongue, a spring-loaded tongue ejector slidable in the passageway, a latch member movable transversely of the passageway between a latching position in which it engages with the latching formation to retain the tongue in the passageway, and a released position in which the tongue is displaceable by the ejector outwardly from the passageway from its retained position, an abutment on the body located on the opposite side of the latch to the passageway, spring means for biasing the latch member into its released position, a first strut located between the latch member and the abutment and engaging with a fulcrum on the latch member for pivotal movement about said fulcrum, a second strut engaging between the first strut and the abutment, stop means on the body for limiting the struts to movement between a first stable position in which the struts hold the latch member in its latching position against the action of its biasing spring, and a second stable position in which the latch member is free to move into its released position, locking means comprising a projecting on the first strut extending into the passageway so as to initiate movement of the struts to their first position when the tongue is inserted into the passageway, and manually operable release means arranged to engage with the first strut to initiate movement of the struts into their second position, the first and second struts being so shaped and the stop means being so positioned relative to the abutment that the distance between the fulcrum and the abutment initially increases as the struts move from each of their stable positions towards the other stable position and is at a maximum when the struts are in a first intermediate position when moving from the first stable position to the second stable position and in a second intermediate position when the struts are moving from the second stable position to the first stable position, the first intermediate position being between the second intermediate position and the first stable position.