Abstract: The rotation of a rotary switch is limited by stop ribs in a knob that facilitates the rotation of the rotary switch. The stop ribs can be configured to limit the rotational stress that is applied to the rotary switch, or to limit the states of the switch that are realizable by a particular knob. Using keyed detachable knobs, different keys can be configured to provide different ranges of rotation of the rotary switch, thereby enabling different switching authorizations, based on the particular knob that is used.

Abstract: Rotary switches, for example key switches, are switched on and off by the rotational movement of a rotary handle. They are intended for mounting on a front plate and are formed in at least two parts. They furthermore have a rotatable switching means and a rotary knob having a key which can be inserted into the switching means. However, the known key switches have no securing means for preventing overturning of the key. In extreme cases—especially with application of excessive force—this leads to the key bit breaking off, which then generally results in tedious and expensive changing of the entire switch. According to the invention, undesired overturning of the key is prevented by ribs which are arranged on the rotary knob and on the front plate or on the switch housing and can come into contact with one another.