Patent ID: 8602173

Claim:
An elevator installation, comprising: an elevator cage disposed in an elevator shaft; a counterweight disposed in the elevator shaft; a first support, the first support extending from a first fastening point in the elevator shaft to the counterweight, from the counterweight to a drive, from the drive to the elevator cage, and from the elevator cage to a second fastening point in the elevator shaft; a second support, the second support extending from a third fastening point in the elevator shaft to the counterweight, from the counterweight to the drive, from the drive to the elevator cage, and from the elevator cage to a fourth fastening point in the elevator shaft, the first and fourth fastening points being positioned diagonally opposed from each other in the elevator shaft; and a monitoring device, the monitoring device comprising, a first slack support switch, the first slack support switch being coupled to the first support near the first fastening point and configured to monitor the first support, a second slack support switch, the second slack support switch being coupled to the second support near the fourth fastening point and configured to monitor the second support, and a safety circuit, the safety circuit being coupled to the first and second slack support switches, wherein an actuation of at least one of the first or second safety switches interrupts the safety circuit.