Breather switch

The rail expansion or the rail expansion device is a component of the track superstructure, which allows larger longitudinal rail movement.

When rail expansion the rails by an oblique cut in a stock rail and an inside -fitting tongue blade are separated. The rails are connected in the overlap region by supporting jaws form-fit to each other. Depending on the design, the tongue or the stock rail is longitudinally movable and can slide.

Rail extensions are installed primarily as a transition structure with larger bridges in the area of ​​the settlement, to obtain no unacceptably large coercive forces in the rail of the longitudinal deformation of the bridge structure. The length changes are mainly caused by thermal expansions, but also by dynamic loads of the bridge ( as braking and acceleration of a train ).

According to the guidelines of the German railway superstructure must be installed from a building length of more than 90 meters at one end fixedly mounted along concrete or composite bridges rail extensions in steel bridges as low as 60 meters.

The construction of a withdrawal path of 700 mm is referred to as " SA -830 " and may be used in steel bridges to about 500 meters and prestressed concrete bridges to about 700 meters in length.

Gallery

Rail expansion on a railway bridge with LZB cable

Indicator for the change in length of a railway bridge