Superstructure K
The superstructure K and its further developed variant, the superstructure KS , are standardized ways of fastening rails on railway sleepers (see superstructure (railway) ).
Superstructure K
With superstructure K, the rail rests with a plastic intermediate layer (formerly poplar wood) on a steel rib plate, the ribs of which guide it laterally and whose slight wedge shape (1:40 ) ensures its inwardly directed transverse inclination (additional measure for self-centering by means of conical running surfaces of the wheels) . With the wooden sleepers used almost exclusively in the past, the standard inclination was 1:20 until the 1960s, in line with the wheel tire profile used on two-axle vehicles at the time. Ribbed plates with this rail inclination are only available on little-used branch lines and in station sidings. Concrete sleepers are usually manufactured with an already inclined support surface for the rails. The hook bolts are inserted horizontally into dovetail recesses in the ribs. The screw shaft is square at the transition to the hook. Together with the two upper edges of a recess, this shaft part acts as an anti-twist device for the hook screw. The top of the hook is spherical so that the screw can adapt to the required transverse and longitudinal inclination.
With the screwed-on nut, the outer leg of the U-shaped clamping plate is pressed onto the rib plate and the inner leg onto the rail foot. The compressive force between the clamping plate leg and the rail causes the higher push-through resistance required for laying rails that are welded without gaps. Depending on the load, the rib plate is connected to the wooden or concrete sleeper with two, three or four sleeper screws. Plastic dowels (formerly wooden dowels) are embedded in the concrete sleepers. In the case of steel sleepers, a special rib plate ("rib support plate") is welded to the sleeper.
For a fastening point with four sleeper screws, 18 parts with a total mass of 17.2 kg are required.
Superstructure KS
In the further development of KS superstructure, the clamping plate and the spring ring have been by a tension spring and a washer replaced. 18 small parts are also required per fastening point with four sleeper screws. The connection between the rail and the sleeper is, however, more flexible. The sleepers can also be delivered to the construction site with preassembled fasteners, as in the case of the later developed track W. The sliding resistance of the rails is greater than that of the superstructure K.
The conversion of existing tracks from the Oberbau K system to the Oberbau KS system is just screwing and can also be done during short breaks. The rails do not need to be lifted.
In turnouts according to German construction principles, the rail fastening according to Oberbau K is also used, but in differently modified form in the area of the switch devices. Switches on concrete sleepers have been fitted with rail fastenings according to Oberbau W since 2007 , with the exception of the switch device area.
literature
- Joachim Fiedler: Railways. Planning, construction and operation of railways, S, U, light rail and trams. 5th edition. Werner Verlag / Wolters Kluwer Germany, Munich / Unterschleißheim 2005, ISBN 3-8041-1612-4 , p. 111ff.
Web links
- gleisbau-welt.de ( Memento from February 11, 2015 in the Internet Archive ) Oberbauarten
Individual evidence
- ↑ HM Waßerroth: The Railway track - Ober type K
- ↑ Studiengesellschaft Holzschwellenoberbau e. V: The wooden sleeper in the superstructure cf. Text from second figure and third figure (technical drawing)