Abstract: A pushbutton, particularly a key of a keyboard, comprises an upper part for operation by finger touch and a lower part serving to operate an activating member, such as an electrical contact, the lower part being constructed with two surface portions of different inclination to the direction of movement of the pushbutton, said surface portions being engaged by a spring wire so as to create a sudden drop of the restoring spring force when the spring wire passes from the more inclined surface portion to the less inclined surface portion.

Abstract: In a tape punching device, punching needle selection takes place by means of selector strips slidably mounted in a rocking arm and engaged by armatures of selector magnets at their rear ends in the vicinity of the rocking axis of the rocking arm. The rocking arm and selector magnets are mounted in a separate case which is insertable in a main housing containing a continuously rotatable main shaft with an eccentric engageable by an open fork at the front end of the rocking arm. The main housing also contains a feeding mechanism alternatively usable for forward feed and back-space through 180.degree. displacement of a pulse supplied to a feeding magnet.