Sand track

from Wikipedia, the free encyclopedia

A sand track is a track covered with coarse-grained sand that is used to stop runaway wagons on inclines. The aim is to brake the escaped wagon through the increased friction caused by the sand between the wheel and the rail, but not the controlled derailment as with a derailment switch (also: sand switch ). The name and the invention of the sand track go back to the German civil engineer Claus Koepcke . Sand tracks are rarely used today.

development

In sloping stations such as the Dresden-Friedrichstadt marshalling yard , a device was needed to stop runaway wagons. Keeping such wagons on a track with a buffer should be avoided because of the damage to the wagon, the buffer and the track. The installation of a buffer stop was also not always possible for reasons of space. The sand track thus offered the possibility of stopping escaped wagons without derailing, damage and (apart from the necessary switches) mechanical components in an outlet section purely by the braking effect of the sand.

Structure and functionality

and display information about the image
Site plan of a sand track
Arrangement of the rails in the sand box
Arrangement of the boundary rails in the sand case

The sand track is integrated into the actual track at its beginning and end with switches and is usually located at the end of a sloping station or at its entrance to stop trains when they enter a dangerous entrance. It can be designed as a separate track outside the actual route and, if there is not enough space, also as a track loop.

The rails of the sand track are lowered with a ramp by 40–45 mm compared to the usual rail in a sand case. This sand case is filled with coarse-grained, clay-free sand up to the height of the rail. The sand box is laterally bounded by two boundary rails or, in the case of the track looping, by the rail. The boundary rails also serve as protection against derailment . If the sand track is designed as a track loop, it is sufficient to swivel the rails of the sand track out to the side by approx. 140 mm in relation to the running rail. This means that no center pieces are necessary.

Interlocking dependency

The points that lead into the sand track are usually coupled to one another, ie both points are switched at the same time. The same position of the switches in and out of the track prevents a wagon that drives through the sand track without stopping from hitting a wrongly positioned switch at the end of the track. In areas of signal boxes where the route is constantly set to the sand track, except when trains are running, the sand track is subject to a special dependency. Only when all other points for a train journey have been correctly set can the points on the sand track be changed. Only then can the signal be set to travel.

See also

source