Hamburg: Passenger compartment doors in local public transport vehicles
In the second example, Hamburger HOCHBAHN AG retrofitted an anti-trap detection system to the pneumatically operated passenger doors in its DT4 underground railway vehicles of the 1st and 2nd series. This involved 50 vehicles, each with four carriages and a total of 800 double-swinging sliding doors. The average number of closing operations per year and door is around 50,000. With a copper-based cable, the first problems occurred in the area of the pivot bearings due to buckling movements after approx. 6 months of use, which prompted HOCHBAHN to look for an alternative cable. The control cable chainflex® CF98 was a possible solution. The alloyed conductor used here is softer in its molecular structure and therefore does not tend to become brittle under bending stress, which increases the downtime. The control cable has managed 450,000 door cycles without any interruptions or error messages during HOCHBAHN test bench trials. As a result, all vehicles were retrofitted in the course of last year. Since then, no more failures have been recorded. Following the positive results of the test bench trials, HOCHBAHN assumes - despite the unchanged high load on the cable in the swivel bearing area - a service life of at least 20 years without any damage.
