Abstract: An apparatus for measuring forces comprises a coil spring within a body; a movable part within the body, the movable part being subjected to the action of the force to be measured and being in contact with one end of the coil spring; a needle on a dial which makes it possible to visualize the correlation between the position of the movable part within the body and the value of the force; an adjustment sleeve within the body with an external thread which can be screwed into an internal thread of the body, the adjustment sleeve being in contact with the other end of the coil spring; the adjustment sleeve has an internal thread within which the coil spring can be screwed; and the external and internal threads of the adjustment sleeve have the same pitch.