Analytic and experimental investigations on a rescue device

With the help of Rescue devices people can rescue themselves out of dangerous situations – e.g. burning sky scrapers. Beside rescue devices for professionals, as they are used by fire men, cable car companies or police men, there are - within the last years - devices on the market for private users. Such a rescue device was investigated on the Institute of Material Handling and Logistic Systems with the aim, to improve the design, so that it could stand a standardized test positively. Like most rescue devices the principle of the rescue device investigated by us is also based on a fly-wheel brake. It consist of two independently working fly-wheel brakes, that are synchronized by a gearbox. With one of the gears, there is rigidly connected a rope wheel. Around this rope wheel lies a rope with rescue overalls on both ends. This way several people can rescue themselves in a pendulum-way out of descend height of up to300 m. The most important characteristic of such rescue devices is their reliability under any thinkable circumstances. To test this reliability, there was published a standard sheet: DIN EN341. This standard sheet defines the specifications and test processes for rescue devices. Following this standard sheet there were done experimental tests at the Institute of Material Handling and Logistic Systems. In these tests we investigated, if the rescue device remained within the prescribed descend speed range between 0,5 m/s and 2,0 m/s under a all planned loads (=30 kg, 75 kg, und 150 kg weight of rescued persons). During the measurements the following weaknesses of the rescue device became visible: 1. the material of the brakes was not enough temperature resistant 2. the real descend speed was sometimes out of the prescribed speed range 3. with a load weight of 150 kg the rescue device was destroyed because of too high temperature To get a deeper understanding about the function of the rescue device, we investigated it additionally by analytical calculation and by simulation with the multi body simulation software ADAMS. With the help of the analytic calculation the dependence of the descend speed on the mass of the brake arms and on the friction coefficient of the brakes could be fixed. With the help of the simulation the processes inside the fly-wheel brake system could be investigated in detail. Based on the results of those investigation methods (measurement, calculation , simulation) the relevant parameters of the rescue device could be changed in a way, so that it now works reliably under any intended load cases.