An electromagnetically operated unit for controlling a radial connection. The unit has a first device which is optionally coupleable with a second device. The second device includes a magnet and/or electromagnet. The unit also has radially movable switching elements that are supported about the circumference of one of the devices, which additionally has contoured and/or frictional surfaces, which mate with respective contoured and/or frictional surfaces of the other one of the devices, thus effectuate engagement of the first and second devices. When the unit is designed with a closed current system the switching elements are biased to disengage when current is applied to the magnet and with an open current system the switching elements are biased to engage, against the force of a spring, when current is applied to the magnet.