Abstract: A hinge joint for use in the seats of motor vehicles has a first leaf which is affixed to the body-supporting part of the seat, a second leaf which is affixed to the pivotable back rest of the seat, and a pintle which provides a pivot for the second leaf. Each of the leaves is provided with a gear and one of the gears surrounds the other gear and has a larger number of teeth. One of the leaves is mounted on two coaxial portions of the pintle, and the gear of the other leaf spacedly surrounds a sleeve which is axially movably mounted on an eccentric portion of the pintle between the two coaxial portions and serves as a retainer for a diaphragm spring which biases the gear of the other leaf axially and radially into mesh with the gear of the one leaf. A needle bearing is interposed between the sleeve and the eccentric portion of the pintle, and a ring can be placed around the diaphragm spring to be in turn surrounded by a passive gear or by a ring-shaped extension of the one component.