Abstract: The roller exhibits a support body which is provided with a plurality of support disks. Insulating layers are arranged between the support disks. A heat-resistant cable surrounding the support body in several coils is embedded in each insulating layer. The insulating layer consists of fiber material which is sprayed on at the same time as the cable is wound around the support body. The cable provides a firm and lasting connection of the insulating layer to the support body.

Abstract: A safety circuit arrangement, especially for transportation systems such as elevators, comprising at least one switching circuit equipped with two digital logical elements, each arranged in a separate information channel and connected at its input side with anti-valent signal generating information transmitters and at its output side with a monitoring circuit monitoring the anti-valence of the output signals. A control line for switching-off the installation in the presence of equivalence. A logical element of the monitoring circuit which is connected at its output side with the control line exclusively comprises diodes and input side logical elements of such monitoring circuit and the monitored digital logical elements are connected with a testing circuit which, upon placing into operation the elevator, applies a test signal simulating a defect in succession to both monitored digital logical elements.