Rubber mixture for an elastic intermediate layer for a rail supp

Details Rubber mixture for an elastic intermediate layer for a rail supp Rubber mixture for an elastic intermediate layer for a rail supp

1996-02-26

1998-04-07

Morano, S. Joseph

Railways: surface track

Rail seats

Cushions

E01B 962

Patent

active

057354570

DESCRIPTION:

BRIEF SUMMARY
BACKGROUND OF THE INVENTION

The Prior Art
Elastic intermediate layers, which are arranged especially in connection with railway tracks between the base of the rail and the top side of the tie (e.g. concrete ties) are known (EP-B-0 295 685, FIG. 1; EP-A-0 541 884, FIG. 1). Such rail supports reduce the vertical rigidity of the track, increase the quietness of the rolling material, reduce the air sound level in the vehicles, and decrease the compression of the bedding.
Elastic rail supports have to be durable (at least 20 years) and stable, resistant to weathering and aging, resistant to water and have to have temperature stability (in the range of from -20.degree. C. to +50.degree. C.), as well as resistant to oil and grease.
Furthermore, as a result of the growing construction of high-speed tracks, rail supports are required to have: (<50 Hz), in the medium frequency range (50 Hz to 400 Hz), and in the high-frequency range (>400 Hz to 2000 Hz); Federal Railway Authority has laid down desired values for a number of test criteria.


SUMMARY OF THE INVENTION

The problem resulting from the high requirements is solved by the use of rubber (E-NR), isoprene rubber (IR), butadiene rubber (BR), acrylate rubber (ACM), styrene-butadiene rubber (SBR), or blends of these types of rubber, especially NR/SBR- or NR/BR-blends, as well as the usual mixing ingredients such as fillers, plasticizers, anti-ageing media, and other additives, if need be:
This rubber mixture is combined with the constructional design of the plate-like, elastic intermediate layer, particularly the rail support described above, whereby the underside of the intermediate layer is provided with at least one recess forming an edge extending all around, said underside facing the top side of the tie, whereas the top side of the intermediate layer, i.e., the surface supporting the base of the rail, is designed substantially planar.
Usefully, the rubber mixture contains a rubber component of from 45 to 75% by weight, particularly of from 55 to 65% by weight.
Useful constructional design variations are also disclosed, whereby said design features are discussed in detail within the framework of the description of the figures.
A mixing formula (table 1) with test results (table 2) is specified hereinafter within the experimental part following now, whereby the following symbols are applicable with respect to the test criteria:


______________________________________ Static axial stiffening C.sub.stat Dynamic axial stiffening C.sub.dyn Static depression f.sub.stat Dynamic depression f.sub.dyn Dynamic stiffening factor .ae butted. ______________________________________
The test specimen was a profiled plate with the following dimensions:


______________________________________ Rectangular shape of the plate 145 mm .times. 160 mm Thickness of the plate 7 mm Edge width 12 mm Number of burls with a rectangular 20 (4 .times. 5) shape viewed from the top Depth of the latticed recess 4 mm Number of venting joints 2 ______________________________________


TABLE 1 ______________________________________ Mixture Components ______________________________________ NR 40.0 SBR 20.0 Soot N 550 25.0 Aromatic plasticizer 8.0 Stearic acid 1.6 Dihydroquinoline derivative.sup.i) 0.3 p-phenylene-diamine derivative.sup.ii) 0.5 Sulfenamide accelerator.sup.iii) 0.7 Zinc oxide 2.4 Sulphur 1.5 100.0 ______________________________________ .sup.i) Example: TMQ .sup.ii) Example: IPPD .sup.iii) Example: CBS


TABLE 2 ______________________________________ Test Criterion Measured values Desired values ______________________________________ 64 60 .+-. 10 90/92/93 100 .+-. 50 as well as at 5 s/10 s/20 s 1.6 .ltoreq.1.7 1.55 .ltoreq.1.6 as well as at 5 s/10 s/20 s .ae butted..sup.i) 1.41/1.44/1.45 .ltoreq.1.8 at 5 s/10 s/20 s 3 -- .sup.iii) 2.9 .ltoreq.3 ______________________________________ ##STR1## .sup.ii) .DELTA.C.sub.dyn = C.sub.dyn (20 s) - C.sub.dyn (5 s)

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