Vehicle seat with adjustable leaf spring

The leaf spring is for suspension of an upper plate (6) relative to a lower plate (7). It has a spring constant adjusting device (20) with two slides, which are positioned on either side of fastener bolts (16.1,16.2) for the spring and are moveable relative to the bolts. The slides are moved via a crank guide having an adjusting device (8) with guide curve (17), and connection elements (11). The leaf spring has a first and a second spring element (1.1,1.2), and the setting device incorporates an adjusting lever (10).