Abstract: A hinge device for supporting an armrest on a vehicle seat includes a ratchet mechanism in which ratchet teeth are disposed around the inside of a ratchet ring for engagement with a pawl carried by a rotor within the ring. A blocking ring coaxial with the ratchet ring is overlapped by the pawl and is carried along by engagement of the pawl in a recess of the blocking ring as the pawl ratchets over the teeth. After clearing the ratchet teeth, the pawl is lifted by cam action from the recess on to the inner surface of the blocking ring which masks the ratchet teeth and allows the pawl to be returned to its starting position where it is restored by cam action to its recess in the blocking ring wherein it can once again engage the ratchet teeth.

Abstract: The hinge mechanism for supporting the back part of a vehicle seat for pivotal movement relative to a base part has first and second hinge arms secured respectively to the back part and base part and interconnected by an eccentric device. The eccentric device is rotatably supported on the first hinge arm and supports eccentrically a shaft integral with the second hinge arm. Rotation of the eccentric device by a handle moves the shaft laterally, and two sets of teeth secured respectively to the hinge arms are thereby moved into or out of mesh. A cam acting between the hinge arms maintains the teeth out of mesh while the back part is in a forward tilted position.