Stackfreed

The stack Freed, misleading also called spring brake, is a simpler mechanism, which is able to compensate for the varying force of the mainspring of a clock by acting supportive braking and upon release of the spring force when fully wound movement. Because the more a tension spring is stretched, the greater the torque delivered by the drive wheel. Freed the stack consists of a with the driving wheel ( referred to in the picture stop wheel ) rigidly connected cam and a leaf spring which presses with a roll on the outer periphery of the cam. Of the torque compensation is optimal when the torque caused by the sum of the tension spring and the stack Freed torques over the entire flow remains constant, which can be achieved by an appropriate design of the cam and a leaf spring.

Most cams are designed more or less worm - or kidney-shaped. When Stack Freed act simultaneously two different mechanical effects, namely friction and torque influences. That exists between the leaf spring and the cam and the bearing of the driving wheel of friction reduces torque, the pressure of the leaf spring on the contour of the cam, but it can reduce both increase (compare function of the heart wheel for the zero position of the pointer in the chronograph ). Theoretical considerations and practical experiments Nuttall Pavel show that the torque generated by the stack Freed sufficient to attain the torque balance. Accordingly, the function of the Stackfreeds less based on friction ( spring brake), as on the torque produced by the stack Freed.

The stack Freed found mainly in southern Germany of about 1510 to about 1650 use, ie after the invention of the "better" compensation mechanism chain / fusee. The reason was that stack Freed was easier to construct and to repair and construction flatter watches allowed.

Origin and meaning of the name stack Freed are unclear. In the Encyclopédie of Diderot and d' Alembert ( Encyclopédie ou Dictionnaire raisonné des sciences, des arts et des métiers ), the mechanism is described stack Freed under the name " stochfred ".