Direct fixation fastener

A bonded, direct fixation fastener as supportive structure for a rail on a railroad bed comprising: a substantially rectangular rail plate, wherein the rail plate has a generally horizontal center portion having a lower face and an upper face and wherein the rail plate defines an outer perimeter having a face defining a first angle to the railroad bed, the rail plate having attachment means to attach to the rail; a substantially rectangular bottom member defines an inner perimeter having a face defining a second angle to the railroad bed; and a substantially rectangular elastomeric portion disposed between, and bonded to each of, the outer perimeter and face of the rail plate and the inner perimeter and face of the bottom member.

FIELD OF THE DISCLOSURE

This present disclosure is related to a direct fixation fastener for attaching a rail to a railroad bed.

BACKGROUND

Bonded direct fixation fasteners (BDFFs) have been used by transit agencies in the United States for many decades. The BDFF design provides a one component solution for the unique needs of the transit railroad systems. Dynamic stiffness of the BDFFs dictates the noise and vibration mitigation performance of the BDFFs. While achieving the desired amount of noise and vibration mitigation, BDFFs must also withstand cyclic wheel loads in diverse environmental conditions for many years. Historically, BDFFs have been made using one grade of rubber and the vertical and lateral stiffness characteristics of BDFFs have been governed by a combination of the geometric details of the design and the properties of the rubber used in the BDFF.

BDFFs with low vertical stiffness are commonly sought to create softer cushions under the rails to provide higher noise and vibration reduction. When the geometrical constraints are set by the end user or track conditions, designers are usually left with softening the rubber element to achieve better noise and vibration reduction. When BDFFs are made softer in the vertical direction, they become softer in the lateral direction as well, which undesirably leads to premature failures under repeated cyclic loading and also to higher lateral deflection of the rail head.

BRIEF SUMMARY OF THE INVENTION

Many other variations are possible with the present disclosure, and those and other teachings, variations, and advantages of the present disclosure will become apparent from the description and figures of the disclosure.

One aspect of a preferred embodiment of the present disclosure comprises a bonded, direct fixation fastener as supportive structure for a rail on a railroad bed comprising: a substantially rectangular rail plate, wherein the rail plate has a generally horizontal center portion having a lower face and an upper face and wherein the rail plate defines an outer perimeter having a face defining a first angle to the railroad bed, the rail plate having attachment means to attach to the rail; a substantially rectangular bottom member defines an inner perimeter having a face defining a second angle to the railroad bed; and a substantially rectangular elastomeric portion disposed between, and bonded to each of, the outer perimeter and face of the rail plate and the inner perimeter and face of the bottom member.

In another aspect of a preferred bonded, direct fixation fastener of the present disclosure, the bottom member and rail plate are cast steel or ductile iron.

In yet another aspect, a preferred bonded, direct fixation fastener of the present disclosure further comprises a rail attachment means comprising channels to receive rail fastening means.

In another aspect of a preferred bonded, direct fixation fastener of the present disclosure, the rail fastening means is a rail clip made of spring steel.

In yet another aspect, a preferred bonded, direct fixation fastener of the present disclosure further comprises a bottom member attachment means for attaching to the railroad bed comprising an aperture for receiving bottom member fastening means.

In another aspect of a preferred bonded, direct fixation fastener of the present disclosure, the bottom member fastening means is selected from the group consisting of a spring, clip, clamp, spike, bolt, and bolt clamp.

In yet another aspect of a preferred bonded, direct fixation fastener of the present disclosure, the elastomeric portion is composed of rubber.

In another aspect of a preferred bonded, direct fixation fastener of the present disclosure, the elastomeric portion comprises rubber.

In a further aspect of a preferred bonded, direct fixation fastener of the present disclosure, the first angle is constant all around the outer perimeter of the rail plate.

In another aspect of a preferred bonded, direct fixation fastener of the present disclosure, the second angle is constant all around the inner perimeter of the bottom member.

In yet another aspect of a preferred bonded, direct fixation fastener of the present disclosure, the first angle is equal or substantially equal to the second angle and each of the first angle and second angle is between about 55° to about 70°.

In another aspect of a preferred bonded, direct fixation fastener of the present disclosure, the elastomeric portion has a uniform or substantially uniform thickness.

In an additional aspect of a preferred bonded, direct fixation fastener of the present disclosure, the elastomeric portion has a hardness of about 47 to about 67 durometer.

In another aspect of a preferred bonded, direct fixation fastener of the present disclosure, the elastomeric portion has a hardness of about 57 to about 67 durometer.

In yet another aspect of a preferred bonded, direct fixation fastener of the present disclosure, the bonded, direct fixation fastener produces a vertical spring-rate in the range of 42000 lbs/in to 61000 lbs/in.

In an additional aspect of a preferred bonded, direct fixation fastener of the present disclosure, the first angle is equal or substantially equal to the second angle and each of the first angle and second angle is between about 55° to about 60°.

In another aspect of a preferred bonded, direct fixation fastener of the present disclosure, the elastomeric portion has a hardness of about 47 to about 57 durometer.

In yet another aspect of a preferred bonded, direct fixation fastener of the present disclosure, the elastomeric portion has a hardness of about 57 to about 67 durometer, and the first angle is equal or substantially equal to the second angle and each of the first angle and second angle is between about 55° to about 65°.

DETAILED DESCRIPTION

An illustrated preferred embodiment of the dual durometer BDFF10of the present disclosure is shown inFIGS. 1-11. The BDFF10comprises a substantially rectangular rail plate20, wherein the rail plate20has a generally horizontal rectangular flat center portion34having a lower face22and an upper face16. The rail plate20has an outer perimeter21having a face30defining a first angle23preferably of about 55° to 70° or also preferably from about 55° to 65° or also preferably from about 55° to 60° to a generally flat horizontal rail bed (not shown). The rail plate20has rail attachment means38to attach the rail plate20to a railroad rail (not shown). The rail plate20may be made of any durable metal or alloy, and is preferably made of cast steel or ductile iron.

A preferred embodiment of the BDFF10of the present disclosure further comprises a substantially rectangular bottom member28, having an interior perimeter29having a face27defining a second angle24, preferably of about 55° to 70° or also preferably from about 55° to 65° or also preferably from about 55° to 60° to a generally flat horizontal rail bed (not shown). The bottom member28may be made of any durable metal or alloy, and is preferably made of cast steel or ductile iron.

Between the rail plate20and the bottom member28is an elastomeric portion44of relatively lower durometer hardness, preferably in the range of 47 to 67 durometer and more preferably in the range of 57 to 67 durometer, bonded to the bottom member interior perimeter29and face27and to the rail plate outer perimeter21and face30. Preferably, the elastomeric portion44is of relatively uniform thickness all the way around the BDFF10.

The rail attachment means38may be any as used in the rail industry. In a preferred embodiment, at least one channel48is formed in the rail plate20. Preferably, the rail plate20may be attached to a railroad rail by means of the channel48using a clip (not shown). More preferably, the clip may comprise a spring clip of a Pandrol design which is in standard use in the rail industry.

The bottom member28is preferably adapted to be attached to the rail bed (not shown). More preferably, the adaption is an aperture54in the bottom member28. The bottom member28may be attached by any means used in the rail industry including spikes, screws, bolts, clips, spring clips, and bolt clamps.

Preferably the BDFF10of the present disclosure produces a vertical spring-rate in the range of 42000 lbs/in to 61000 lbs/in.