Abstract: A lever mechanism including a lever which is pivotally mounted between its ends on a pivot shaft forming two lever arms. One of the lever arms is arranged to receive a force applied thereto and the other of the lever arms has an end portion arranged to transmit movement and force to a working element. The end portion has part-cylindrical surfaces which cooperate with part-cylindrical surfaces on oppositely located slide blocks. Each slide block has a planar slide surface which is parallel to a shaft of the part-cylindrical surfaces of the end portion. The planar surface of each slide block is arranged to slidably abut a planar surface on the working element. The slide blocks are non-rotatably connected to each other via their planar slide surfaces in parallel planes by means of dogging elements which are pivotally mounted on the shaft of the part-cylindrical surfaces of the end portion.