Screw dowel for fastening rails

Abstract

Screw dowel for concreting into a railway sleeper or ballastless track and frictionally connecting to a sleeper screw, containing a threaded portion (14) with external thread flights (18) arranged on the outside of the screw dowel (10) and with internal thread flights (19) arranged on the inside of the screw dowel; and an upper subportion (16) without external thread that is situated close to the dowel opening (26) in the installed state; the screw dowel containing two constituent parts made of different materials, namely a basic body made of plastic and a cylindrical ring (20) made of a steel material and mounted with a form fit and / or force fit.

Description

FIELD OF THE INVENTION[0001]The invention relates to a screw anchor for the concrete attachment in a railroad tie or non-ballasted track according to the preamble of claim 1. Moreover, the invention relates to a railroad tie or non-ballasted track with at least one screw anchor according to the invention.PRIOR ART AND PROBLEM[0002]Screw anchors for the concrete attachment in a railroad tie are used in railway engineering for connecting rail to tie. In this arrangement, the rail attachment is connected to the tie by means of rail screws. The screw anchors are often made of plastic and can be cast into a concrete tie or a non-ballasted track during manufacture. One reason that the anchors are often made of plastic is because the rail screw must be electrically insulated from the tie and because plastic is a cheap flexible material which is simple to process and use.[0003]A disadvantage resulting from this is that the screw anchors made of plastic often have different mechanical and ph...

AI Technical Summary

Benefits of technology

The technical effect of this patent is to create an anchor for attachment in a railroad tie or non-ballasted track that reduces stress build-up in the surrounding concrete.

Problems solved by technology

A disadvantage resulting from this is that the screw anchors made of plastic often have different mechanical and physical properties from the surrounding material.

This can lead to disadvantages, particularly in concrete tie manufacture but also in later operation, as an anchor initially in form-fit contact with the concrete expands more than the surrounding concrete when the temperature rises so that pressure is exerted on the concrete.

Cracks and fissures can occur around the anchor or radially if there are high thermal stresses.

Depending on the rail attachment system and the specific clamp system used (e.g. tension clamp), forces are introduced into the concrete tie resulting in lateral tensile stresses, which can cause a widening of the crack and can encourage subsequent crack growth.

Water and / or dirt can thereby penetrate into the concrete and, as a result, further damage to the tie can occur due to cracks getting bigger, which has a negative effect on the service life of the tie.

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