Abstract: An office chair seat carrier includes a seat platform carrier and a back rest carrier pivotally connected about parallel rotatable axes to a carrier part. A stack of lamellar disks is pivotally connected between the carrier part, seat platform carrier, and back rest carrier for holding the carriers in place by frictional contact. The stack of lamellar disks is linked with a holding member rigidly attached to the carrier part. Frictional contact is established by activating an actuator lever which slides a clamping member against the stack of lamellar disks. The clamping member applies a lateral clamping force upon the stack of lamellar disks forcing the disks together. Frictional contact is broken only after the actuator lever releases the clamping force and a mechanical force is exerted on the seat platform carrier or back rest carrier.