Preload device for a circuit board

A control apparatus for a power tool, the control apparatus comprising:

• at least one circuit board;
• a heat-conductor;
• a cooler for cooling the at least one circuit board;
• at least one housing element, wherein, in a mounted state of the control apparatus, the circuit board and the heat-conductor are arranged between the cooler and the housing element, and the heat-conductor is positioned between the circuit board and the cooler;
• and
• a preloader between the housing element and the at least one circuit board to press the circuit board against the heat-conductor in a predefined direction;
• the preloader including a first spring and a second spring;
• the first spring having a first extent in a direction and the second spring having a second different extent in the direction,
• wherein the preloader includes a plurality of springs in addition to the first and second springs.