Railways: surface track – Fastenings – Spikes
Patent
1995-04-25
1998-06-02
Le, Mark T.
Railways: surface track
Fastenings
Spikes
238370, 411439, E01B 900
Patent
active
057588210
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an elastic rail fastening system for rails mounted on a cross tie, the foot of the rail being clamped by metal rail spikes which are anchored in the cross tie and comprise a shank and a head arranged eccentrically thereon, an electrically insulating plastic element being arranged on the rail spike, as well as a rail spike for such a fastening system.
2. Description of the Prior Art
For the fastening of rails to cross ties, elastic or rigid steel parts, including rail spikes, are frequently used, a large number of differently developed structural parts being required for the elastic transfer of the large horizontal and vertical forces. With respect to rail current systems, particularly signal currents, it has also already been proposed to insulate rail spikes electrically from the rails by plastic parts.
A rail spike fastening of this type is known from U.S. Pat. No. 3,080,120. In that case, a rail spike is seated vertically in a wooden tie. Before the rail spike is driven in, a shaped part of non-deformable steel-hard nylon with fiberglass reinforcement is placed over it providing electrical insulation from the foot of the rail after the spike has been driven in. In this connection, the plastic element preferably does not lie on the cross tie. The flexural wave of the rail produces sudden stresses on the rail spike in a vertical direction with the result that the spike loosens and the clamping is reduced. An ordinary commercial element, for instance an elastic interlayer of plastic, may be placed beneath an intermediate plate or rib plate which bears the rail. Since the spike retains its position after being driven into the wooden tie and the insulating plastic element below the head of the spike is not deformable, in contradistinction to the intermediate layer, vertical stresses are produced when the place of attachment is traveled over, thus leading to a complete loss of the clamping force of the rail attachment. Furthermore, the resting of the head of the spike on the plastic part is not always assured, since the elasticity of the rail spike itself makes it necessary to expect a rebounding back of the head of the spike from the hard plastic part. By the rigid clamping in the wooden tie and the steel-hard plastic element lying above it, no prestressing which could impart additional security to the rail attachment can be obtained in the shank of the spike even when the head of the spike rests on the plastic element.
EP 0 393 432 A2 discloses a rail fastening on ties using a rail spike having a special pressure-distributing plate below its head in which the shank of the spike is to be driven into a concrete or wood cross tie at a right angle to the surface of the foot of the rail. Before the intended position of the head of the rail spike is reached, an elastic plastic element which consists of cold-resistant, high-modular, thermoplastic polyurethane with a compressive strength of greater than or equal to 35 N/mm.sup.2 and an elastic pressure deformability of up to 40% is inserted between the head of the spike and the foot of the rail. This type of fastening by rail spike has several disadvantages. The mounting of the rail spike is cumbersome, since the spike must first be driven in for a distance, whereupon the plastic part must be properly placed on, and the foot of the rail may have to be aligned again without it losing its position upon the further driving in of the spike. Furthermore, the arrangement of the rail spike relative to the introduction of the force from a working stress via the rail and the foot of the rail is unfavorable since a tilting of the rail results in an immediate pulling of the spike with a small retention force on the part of the spike.
Rail spikes having a polygonal shank are known, for instance, from German Standards DIN 5911 and 5912 and are made of pressed or forged steel. The shank is provided on one end with a nose-shaped head and on its other end with a wedge tip.
SUMMARY OF THE INVEN
REFERENCES:
patent: 747804 (1903-12-01), Thompson
patent: 999771 (1911-08-01), Forsyth
patent: 1294778 (1919-02-01), Cutting
patent: 2557271 (1951-06-01), Fulton
patent: 2719452 (1955-10-01), Jones
patent: 3080120 (1963-03-01), De Turk
patent: 3191864 (1965-06-01), Moses
patent: 4066212 (1978-01-01), Sonneville
patent: 4134546 (1979-01-01), Dankert
Bonewitz Wilfried
Wirthwein Udo
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