Flexicoil coil spring
The Flexicoil suspension is a low-wear and maintenance-free suspension that is used in railway vehicles. It is installed as a secondary spring between the bogie and the car or locomotive body . It is mainly used in modern passenger coaches when air suspension is not required, as it is cheaper to buy and maintain than air suspension.
The springs are on top and bottom on a spherical rubber cap that can absorb part of the horizontal forces. These spheres are firmly connected to the box (above) and to the bogie frame (below) of the vehicles . The Flexicoil spring is therefore twisted when cornering and shifted from its vertical axis. This helps the two bogies to align themselves evenly under the car body . The vertical forces are completely absorbed by the steel springs.
Since the spring has a relatively soft characteristic, hydraulic vertical dampers must be installed to dampen vibrations , as well as longitudinal dampers at speeds higher than 160 km / h. Side cushioning is usually not required.
On passenger cars, the springs are the only mechanical connection between the bogie and the car body. The pivot usually engages in a rubber-metal bearing of the lemniscate yoke, which transfers the forces to the bogie frame via the two lemniscate links .
The bogies of the locomotives are usually also provided with a deep linkage or another transmission of traction.