Note: Descriptions are shown in the official language in which they were submitted.
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RAIL ASSEMBLY AND COMPOSITE POLYMER CROSSTIES THEREFOR
TECHNICAL FIELD
[0001] The present disclosure relates to rail assemblies, and in
particular, to a rail
assembly and composite polymer crossties therefor.
BACKGROUND
[0002] Conventional wooden timber crossties and concrete railway
crossties
coupling systems require that the railway rails be coupled to the crosstie
such that the two
railway rails maintain a specific spacing corresponding to the wheel spacing
of wheels
coupled to an axle of a railway car. A rail is typically coupled to the
crosstie by way of
two or more rail clips which are coupled to the crosstie by way of an
intervening tie plate
fastened to the crosstie using spikes or screw-type spikes. A portion of the
clip
correspondingly applies pressure to the railseat to maintain the rail against
the crosstie.
[0003] The compressive forces exerted by a train as it passes over a
given railway
crosstie are known to cause degradation in the railway crosstie. For example,
in the case of
wooden crossties, the compressive force of the base (railseat) of the railway
rail, with the
tie plate thereunder, against the crosstie as a train passes thereover, over
time causes the
wood fibres of the crosstie to breakdown. Therefore the railway rail, or the
tie plate in
instances where one is present, cuts into the wood and a gap is formed between
the bottom
of the railway rail and the crosstie. Similarly in the case of concrete
crossties, the
compressive forces cause the concrete and/or a compression pad ("also termed a
cushion
mat") under the tie plate to wear under the railway rail and a gap to form.
Repeated train
travel along the rails causes the rail to flex into the created gap and impact
the crosstie,
thus causing further breakdown of the crosstie and the gap to increase in
size. With
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concrete crossties, the impact of the rail across the gaps may cause the
concrete crosstie to
fracture, leading to catastrophic failure.
[0004] Also, as the gap increases, the constant flexing and retraction
of the rail as a
train travels thereover is known to cause the fasteners coupling the rail or
tie plate to the
crosstie to loosen. This creates a situation where the gap is further
increased and/or the rail
becomes uncoupled from the crosstie. In such cases where uncoupling occurs, if
the
crosstie has not suffered a failure where it needs to be replaced, the
crosstie will need to be
"re-spiked" which is time-consuming and costly. During re-spiking, the
original spike hole
must be plugged and a new spike bore made. The rail can then again be coupled
to the
crosstie.
[0005] In order to reduce the incidence of catastrophic failure, in
both the case of
wooden crossties and concrete crossties, maintenance crews must be deployed to
survey
railway lines for developing gaps between railway rails and corresponding
crossties. Once
a gap is detected the maintenance crew must undertake to tighten the fasteners
and secure
the rail against the crosstie. However, by such a time, significant damage may
have
already been done to the crosstie. For example, in the case of a wooden
crosstie, once a
gap of from about 3/8" to about 1/2" is developed, the rail must be tightened.
[00061 In order to mitigate a gap developing, the industry has accepted
the use of
surface area-increasing force-distributing plates and/or cushion mats being
placed between
the bottom of the rail and the crosstie. For example, resilient cushioning
mats, or cushion
mats are used in conjunction with concrete crossties to minimize abrasion of
the railseat
area, and reduce impact and vibration effects on the track structure in an
attempt to
minimize gaps from forming. In the case of wooden crossties, a surface area-
increasing
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force-distributing steel plate is often used between the railseat and the
crosstie to increase
the surface area and distribute the compressive forces from the train over a
larger area of
the crosstie. This aids to reduce the wood fibres immediately under the rail
from breaking
down as rapidly as if the surface area-increasing force-distributing steel
plate were not
present. However, it is known that with both of these approaches, the
crossties still
breakdown by way of the compressive forces, and/or abrasion, and the fasteners
retract
from their respective seats resulting in a gap between the bottom of the rail
and the
crossties still forming. Therefore, the use of cushion mats and surface area-
increasing
force-distributing steel plates serve to increase the life a crosstie, but
significant
maintenance to tighten the rails to the crossties is still required.
Furthermore, the required
use of the cushion mats and surface area-increasing force-distributing steel
plates increases
the unit cost of each crosstie installation.
[0007] United States Patent Application Publication number US
2006/0226247 Al,
published October 12, 2006 to Abramson, et al. and entitled "Railway Ties and
Structural
Elements" describes a composite structural element such as a railway tie made
from an
asphaltic component and a fibre reinforced plastics component.
[0008] United States number 8,252,216, issued August 28, 2012 to
Abramson, et al.
and entitled "Method for the Production of Railway Ties" describes a method
for
producing composite railway ties from two co-extruded compositions where each
composition comprises an asphaltic component, a polymeric component and a
strengthening agent. The strengthening agent may be a fibre and is preferably
a glass fibre.
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[0009] This
background information is provided to reveal information believed by
the applicant to be of possible relevance. No admission is necessarily
intended, nor should
be construed, that any of the preceding information constitutes prior art.
SUMMARY
1000101 The following presents a simplified summary of the general
inventive
concept(s) described herein to provide a basic understanding of some aspects
of the
invention. This summary is not an extensive overview of the invention. It is
not intended
to restrict key or critical elements of the invention or to delineate the
scope of the
invention beyond that which is explicitly or implicitly described by the
following
description and claims.
[00011] There
is a need in the industry to provide a system including a crosstie which
is more resistant to compressive forces exerted by a passing train and one
which improves
fastener retention. Also, it would be advantageous to provide a system which
can meet the
abovementioned needs, as well as other needs, with fewer parts, lower overall
material
costs, installation costs and/or lifetime maintenance costs. Lower lifetime
maintenance
cost may, for example, be realized by less required maintenance over the
lifetime of a
given crosstie installation.
[00012] It
has been surprisingly discovered that using a system such as that
described herein which makes use of composite polymer crossties improves the
coupling
of railway rails to crossties over the conventionally used wood or concrete
crosstie
systems. For example, in various testing models employed it was shown that
using the
system disclosed herein, rail/plate area compression testing of the crossties
returned values
far exceeding industry requirements, and embedded screw-spike/threaded insert
pull-out
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testing also returned values far exceeding the industry requirements and that
which is
conventionally expected for wooden, concrete and other composite crossties.
[00013] In accordance with one aspect, there is provided a railway tie
assembly for
securing a rail along a railway track, the assembly comprising: a plurality of
composite
polymer crossties fabricated from a composition comprising an asphaltic
component, a
polymeric composition component and a strengthening agent; and a pair of rail
clips for
securing the rail across each of said composite polymer crossties, wherein
each of said rail
clips comprises a rail-engagement portion configured to engage a corresponding
railseat,
and an anchoring portion to be anchored within a given crosstie and cooperate
with said
rail-engagement portion, once installed, to secure said corresponding railseat
against a
load-bearing surface of said given crosstie.
[00014] In accordance with one such aspect, an anchoring of the rail to
said
crossties maintains or strengthens the anchoring portion's gripping power to
the crosstie
under use by virtue of said composition.
[00015] In accordance with another aspect, there is provided a railway
track
comprising: a plurality of composite polymer crossties fabricated from a
composition
comprising an asphaltic component, a polymeric composition component and a
strengthening agent, wherein said crossties are disposed at regular intervals
along the
railway track; one or more rails each composed of rail segments juxtaposed end-
to-end
along the railway track, a respective railseat thereof disposed crosswise upon
a respective
load-bearing surface of each of said crossties; and respective pairs of rail
clips securing
respective ones of said rail segments to each of said composite polymer
crossties, wherein
each of said rail clips comprises a rail-engagement portion engaging a
corresponding
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railseat, and an anchoring portion anchored to a given composite crosstie and
cooperating
with said rail-engagement portion to secure said corresponding railseat
against said
respective load-bearing surface of said given crosstie.
1000161 In
accordance with one such aspect, an anchoring of said rail segments to
said crossties is maintained or strengthened under use by virtue of said
composition.
[00017] Other
aims, objects, advantages and features of the invention will become
more apparent upon reading of the following non-restrictive description of
specific
embodiments thereof, given by way of example only with reference to the
accompanying
drawings.
BRIEF DESCRIPTION OF THE FIGURES
[00018] In
order that the invention may be better understood, exemplary
embodiments will now be described by way of example only, with references to
the
accompanying drawings, wherein:
[00019]
Figure la is a top perspective view of a portion of an exemplary composite
polymer crosstie having a railseat receiving rectangular channel formed
therein, in
accordance with one embodiment;
[00020]
Figure lb is a top perspective view of a portion of a composite polymer
crosstie having an exemplary railseat and abrasion guard receiving rectangular
channel
formed therein, as shown in ghost lines, in accordance with one embodiment;
[00021] Figure lc is a front elevation view of the composite polymer
crosstie portion
of Figure la showing a cross-sectional view of a rail section mounted thereon
with a
railseat thereof received in the rectangular channel;
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[00022] Figure 2a is a top plan view of the composite polymer crosstie
portion of
Figure la showing a rail portion coupled thereto using exemplary inner and
outer rail clips
and with a portion of the railseat received in the rectangular channel, in
accordance with
one embodiment;
[00023] Figure 2b is a top plan view of the composite polymer crosstie
section of
Figure lb showing a rail portion coupled thereto using exemplary inner and
outer rail clips
and with a portion of the railseat and an exemplary abrasion guard received in
the
rectangular channel;
[00024] Figure 3a is a top plan view of a portion of railway tracks
showing a plurality
of the composite polymer crossties of Figure la with two rail sections coupled
thereto
using exemplary inner and outer rail clips and with portions of the respective
railseats
received in respective rectangular channels;
[00025] Figure 3b is an enlarged top perspective view of a portion of
the rail
installation of Figure 3a showing inner and outer shims in communication with
respective
inner and outer rail clips and further showing in cross section the railseat
received in the
rectangular channel, in accordance with one embodiment;
[00026] Figure 4 is a side view of an alternative rail installation
similar to that shown
in Figure 3b showing inner and outer rail clips coupled to the composite
polymer crosstie
using fasteners bored into the composite polymer crosstie (shown in ghost
lines), and
further showing an abrasion guard received along an outermost sidewall of the
rectangular
channel;
[00027] Figure 5 is a side view of an alternative rail installation
similar to that shown
in Figure 4, comprising an extended abrasion guard having a flange portion
extending
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along a top surface of the composite polymer crosstie and along a bottom load-
bearing
surface of the rectangular channel;
[00028]
Figure 6 is a side view of an alternative rail installation similar to that
shown
in Figure 5, comprising a further extended abrasion guard having an inner
rectangular
channel sidewall portion;
[00029]
Figure 7 is a top perspective view of a partially assembled rail assembly
composed of an exemplary composite polymer crosstie having a railseat-
receiving wedge
formed therein and opposed rail clip anchoring structures fastened on either
side thereof to
directly or indirectly restrict a lateral travel of a railseat subsequently
disposed
therebetween;
[00030]
Figure 8 is a top perspective view of the assembly of Figure 7, further
showing respective rail-engaging portions slidingly received within
corresponding
anchoring portions of the anchoring structures in a pre-assembled
configuration, a rail
received inclined in the railseat-receiving wedge, and respective collars
disposed about the
anchoring portions to directly restrict a lateral travel of the railseat
resting therebetween;
and
[00031]
Figure 9 is an enlarged perspective view of the assembly of Figure 8 once
fully assembled, showing a sliding engagement of the rail-engaging portion
upon the
railseat.
DETAILED DESCRIPTION
[00032] With
reference to the disclosure herein and the appended figures, a rail
assembly and composite polymer crossties therefor will now be described in
accordance
with various embodiments of the invention.
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1000331 With reference to Figures la, lb and lc, and in accordance with
one
embodiment, an exemplary composite polymer crosstie 12 is shown for use in a
rail
assembly as contemplated herein and described below (e.g. see assembly 10 of
Figure 2a).
In this embodiment, the composite polymer crosstie 12 has a rectangular
channel 14
formed or cut in a top surface 16 thereof for receiving therein a base portion
or railseat 18
of a railway rail 20 as shown in Figure lc. In some embodiments the
rectangular channel
14 is dimensioned across distance A to substantially match the width of the
railseat 18.
However, in other embodiments shown for example in Figures 4 to 6, the
rectangular
channel 14 may be dimensioned across A to also fit an abrasion guard 22 along
with the
railseat 18. In these embodiments, the rectangular channel is further
dimensioned to have a
depth B suitable to accommodate the railseat 18, and optionally different
embodiments of
the abrasion guard 22 as shown in Figures 4 to 6. An exemplary depth B for use
with the
various embodiments of abrasion guards 22 is also shown in ghost in Figure lb
relative to
the rectangular channel 14 for use in embodiments devoid of an abrasion guard
22.
Accordingly, the rectangular channel 14 serves to inhibit or prevent lateral
movement of
the railway rail 20 relative to the crosstie 12 during use.
[00034] Turning now to the rectangular channel 14, a bottom load-bearing
surface 24
of the rectangular channel 14, in some embodiments, is provided such that it
is parallel
with the composite polymer crosstie 12 top surface 16. However, in some
embodiments
the railhead 26 may be inwardly inclined or canted (i.e. toward one another in
a two rail
assembly) as shown, for example, in Figures lc, and 4 to 6 at angle 0.
Accordingly, the
bottom surface 24 may be provided at an angle which is inclined towards an
outer edge 28
of the composite polymer crosstie 12. The cant angle 0 to the rail 20, and
thus the railhead
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26 resultant from the outward incline of the bottom surface 24, is shown in
the figures
relative to vertical at O. The cant to the railhead 26 may be, for example,
from about 1:40
to about 1:10 dependent on that required by the specific application of the
rail assembly
and composite polymer crossties 12 used therefor. In some examples, the cant
is provided
at about 1:20. The cants noted herein should not be considered to be limiting
and are
provided for exemplary purposes, only. One of skill in the art would readily
understand
which cants may be required for specific applications. In other embodiments
the bottom
surface 24 may be provided as being parallel with the top surface 16 and the
abrasion
guard 22, in embodiments with an abrasion guard bottom portion 22a, as shown
in Figures
5 and 6, for example, may be fashioned to provide the desired cant to the
railhead 26.
Therefore, in such embodiments the abrasion guard base portion 22a may be
wedge-
shaped to provide the outward incline as noted above.
[00035] With reference now to Figures 3a and 3b, and in accordance with
one
embodiment, a plurality of composite polymer crossties 12 are provided to have
coupled
thereto and maintain two rails 20 at a desired spacing. Figure 3b shows an
enlarged
perspective view of the assembly 10 in relation to a cut through section of
one of the rails
20. The railseat 18 is laid into a correspondingly dimensioned rectangular
channel 14 such
that the railseat 18 fits substantially snuggly in the rectangular channel 14.
An inner rail
clip 30 and an outer rail clip 32 are provided to maintain the railseat 18 in
the rectangular
channel 14 and thus couple the rail 20 to the composite polymer crosstie 12.
[00036] Both the inner rail clip 30 and the outer rail clip 32 are
provided in the
embodiments described herein as having a substantially "W" shape, as can be
seen in the
figures. Furthermore, as can be seen in Figures 3b to 6, for example, the
inner rail clip 30
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and the outer rail clip 32 have and arced profile which aids to provide
resiliency against
vibrations from a train passing along the rails and to maintain the rail 20 in
coupled
arrangement with the composite polymer crossties 12. Such resiliency provided
by a
formed arc of the inner and outer rail clips 30 and 32 allows a degree of
bending of the rail
clips under load and resists fracturing of the rail clips with repeated
vibrations and train
travel. Should the inner rail clip 30 and the outer rail clip 32 not be
provided with some
degree of resiliency, they may have a tendency to prematurely crack and fail.
1000371 The inner rail clip 30 has a shim contacting outer portion 30a,
a rail
contacting inner portion 30b (e.g. rail-engagement portion) and a center
region (e.g.
anchoring structure) having a fastener passage 30c, as shown, for example in
Figure 2a.
Similarly, the outer rail clip 32, also as shown in Figure 2a, has a shim
contacting outer
portion 32a, a rail contacting inner portion 32b and a center portion having a
fastener
passage 32c.
1000381 As shown in the figures, a fastener 34 is passed through the
fastener passages
30c and 32c located in the center portion of the respective rail clips 30 and
32. The faster
34 is inserted and maintained in a bore 36 of the composite polymer crosstie
12 as shown,
for example, in Figures 4 to 6. In some embodiments, such as the ones provided
in the
figures, the fastener 34 may be provided as a screwspike fastener having
helical threads as
is commercially available and known in the art. In other embodiments (not
shown), the
fastener 34 may be provided as an impact force-driven spike which is devoid of
helical
threads. The general shape of the inner and outer rail clips 30 and 32 should
not be limited
specifically to a "W" shape as other rail clips, such as that described below
with reference
to Figures 7 to 9 in accordance with another illustrative embodiment, may be
readily
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considered herein without departing from the general scope and nature of the
present
disclosure. The "W" shape is noted herein as an example, only, other shapes
for the inner
and outer rail clips 30 and 32 may be suitable. For example, such a shape for
one or both
of the inner and outer rail clips 30 and 32 may be a "V" shape, a "U" shape, a
"J" shape,
an "N" shape, and so on.
[00039] With reference to Figure 3b, the assembly 10 also includes shims
38 and 40,
which, in use, are respectively placed on the top surface 16 of the composite
polymer
crossties 12 under the shim contacting outer portions 30a and 32a of the inner
rail clip 30
and the outer rail clip 32 respectively. The fasteners are then inserted and
driven into the
composite polymer crossties 12 as shown in the figures, passing through the
respective
inner and outer rail clip fastener passages 30c and 32c. Therefore, in use,
the rail
contacting inner portions 30b and 32b of the respective inner and outer rail
clips 30 and
32, with the fasteners 34 in place maintain, the railseat 18 in the
rectangular channel 14.
The inner shim 38 and the outer shim 40 are provided to elevate the shim
contacting outer
portions 30a and 32a and thus increase the toe pressure of the rail contacting
inner portions
30b and 32b on the respective areas of the railseat 18, as shown in particular
in Figures 3b
to 6. Additionally, as shown in the aforementioned figures, in some
embodiments, it is
preferable to have the outer shim 40 be of a greater height or thickness as
compared to the
inner shim 38 so as to increase the toe pressure applied to the railseat 18
along the outer
side thereof (i.e. in a two rail system). Such increased toe pressure of the
outer rail clip 32
compared to the inner rail clip 30 may be used, for example, in applications
where the
railhead 26 is inwardly inclined as shown in Figures 4 to 6 by way of an
outwardly
inclined rectangular channel bottom surface 24, as discussed above. The
increased toe
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pressure provided by the outer shim 40 having an increased thickness versus
the inner
shim 38, may also aid to maintain the railseat 18 in the rectangular channel
14 and counter
the downward forces applied to the railhead 26 by a train passing thereover.
In
embodiments where the railhead 26 is inwardly inclined, as shown in Figures 4
to 6, for
example, should sufficient toe pressure not be applied at the rail contacting
inner portion
32b of the outer rail clip 32, the rail 20 may have a tendency to rotate
inward and lead to
failure of the system. In some embodiments, the toe pressure of the rail
contacting inner
portions 30b and 32b on the respective areas of the railseat 18 is provided in
a range from
about 500 psi to about 10,000 psi by way of tightening corresponding fastener
34 and the
interaction of the shim contacting outer portions 30a and 32a with shims 38
and 40,
respectively. Additionally, for example, the dimensions of shims 38 and 40 may
also be
varied in order to achieve the desired toe pressures. In preferred embodiments
the toe
pressure of the rail contacting inner portions 30b and 32b is provided in a
range from
about 2,000 psi to about 3,200 psi. Various different toe pressures may be
required
depending on the application of the assembly defined herein so as to couple
the railway
rail 20 to the crosstie 12 in different environments and may be readily
determined by one
of skill in the art.
[00040] As discussed below in more detail with respect to the testing of
the composite
polymer crossties 12 of the instant disclosure, although the composite polymer
crossties 12
of the system 10 as disclosed herein are more resistant to abrasion and
compressive forces
compared to conventionally used wooden crossties, in some instance it may be
desirable
for the system 10 to include an abrasion guard 22. Various embodiments and
orientations
of the abrasion guard 22 are discussed above in relation to their installation
relative the
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railseat 18 and the rectangular channel 14. More specifically, the abrasion
guard 22 in one
embodiment, as shown Figure 4, may be placed in the rectangular channel 14
along an
outermost side wall 42 of the rectangular channel 14. In such an embodiment,
the
rectangular channel 14 along distance A is made wider so as to accommodate the
width of
the railseat 18 plus the abrasion guard 22. For example, with an abrasion
guard 22
fashioned and employed as shown in Figure 4, the forces exerted on the rail 20
by a train
passing thereover and applied both downward and in the direction towards the
outer edge
28 of the composite polymer crosstie 12 are absorbed by the abrasion guard 22
so as to
reduce damage/wear to the composite polymer crosstie 12 along the outermost
side wall
42 of the rectangular channel 14. Additionally, such an abrasion guard 22 may
also aid to
afford protection against cracking or fracturing to the composite polymer
crosstie 12
starting at the intersection of the outermost side wall 42 and the rectangular
channel
bottom wall 24 as well as damage to the outermost side wall 42 itself owing to
forces
resultant from trains repeatedly passing along rail 20.
1000411 Figure 5 shows another embodiment of the abrasion guard 22 wherein
an
abrasion guard base portion or flange 22a is provided. In such an embodiment
the abrasion
guard 22 is fashioned to line the outermost sidewall 42 as well as the bottom
wall 24 of the
rectangular channel 14. The railseat 18 then rests on the abrasion guard base
portion 22a,
in use. As shown in Figure 6 with respect to another embodiment of the
abrasion guard 22,
an innermost sidewall 46 of the rectangular channel 14 is also lined with a
portion of the
abrasion guard 22, namely an inner rectangular channel sidewall abrasion guard
portion
44. Therefore, in the embodiment shown in Figure 6, the abrasion guard 22 is
fashioned to
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form a substantially "U-shaped" member in profile, which lines the interior
surfaces of the
rectangular channel 14.
[00042] In other embodiments (not shown), two independent abrasion
guards may
rather be provided where one of the abrasion guards is located along the
outermost
sidewall 42 of the rectangular channel 14 as shown in Figure 5 and the other
of said
abrasion guards 22 is located along the innermost sidewall 46 of the
rectangular channel.
In such an embodiment, the abrasion guards may be considered to be
respectively an outer
rectangular channel sidewall abrasion guard and an inner rectangular channel
sidewall
abrasion guard.
[00043] Although abrasion guards 22 such those shown in the embodiments of
Figures 4 to 6 may be optionally used in various embodiments of the system 10
as
described herein, the abrasion guards 22 do not substantially increase the
surface area
from which forces from a train passing over the rails 20 are exerted on the
composite
polymer crossties 12; in other words, these rail guards do not substantively
increase a
load-bearing area of the crossties, as would otherwise be provided by
conventional tie
plates used in wooden rail assemblies. Therefore, the assembly 10 generally
consists of a
plateless system, that is one absent a force-distributing plate. Unlike force-
distributing
plates which are used with conventional wooden crossties and variations
thereof in the
case of conventional concrete crossties, the optional abrasion guards noted
herein are
provided for the purposes of inhibiting abrasion damage and fracturing of the
composite
polymer crossties 12 at certain points of the railseat 18 maintaining
rectangular channel
14. The various embodiments of abrasion guards 22 disclosed herein do not act
to
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substantially increase the surface area of the railseat 18 to distribute
compressive forces
over a larger area of the crosstie.
1000441 Additionally, in some embodiments, such as the ones shown for
example in
Figures 5 and 6, the abrasion guard 22 may be fashioned to have a flange
portion 48 which
extends along a portion of the top surface 16 of the composite polymer
crosstie 12 towards
the composite polymer crossties outer edge 28. In some embodiments, the outer
shim 40
may be coupled to the flange portion 48, whereas in other embodiments, the
outer shim 40
may be integrally formed with the flange portion 48. The flange portion 48, in
the various
abovementioned embodiments, may have a passage made therein (not shown) for
receiving therethrough a portion of the fastener 34 employed with outer rail
clip 32. By
having the flange 48 receive therethrough a portion of the fastener 34, the
abrasion guard
22 is resistant to movement and as such is not able to move out of place in
the rectangular
channel 14. Vibrations caused by repeated train travel over the rails 20 may
cause
unsecured abrasion guards 22 to move from the desired position and thus in
certain
applications it may be desirable to protect against abrasion guard 22
movement.
1000451 With reference to Figures 7 to 9, an alternative rail assembly
100 will now be
described in accordance with another embodiment. In this embodiment, the rail
assembly
100 again makes use of composite polymer crossties 112 upon and across which
one or
more rails 126 are mounted and secured via respective rail clips 130, 132.
Rather than to
provide a rectangular rail receiving channel, as shown above with reference to
Figures 1 to
6, a wedge-shaped cutout 114 is fashioned in a top surface 116 of the crosstie
112 so to
receive inclined a correspondingly shaped railseat 118 therein. To secure
against lateral
travel of the railseat 118 once in position, the rail clips 130, 132, in
accordance with one
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example, are preassembled with the crossties 112 via respective screw-type
fasteners 135
to substantially define thereon the rail load bearing surface therebetween.
For instance,
respective clip anchoring structures 134 may be anchored to the crosstie via
respective
anchoring fasteners (e.g. screw type threaded fasteners or the like) so to
define the rail
load bearing surface therebetween, for instance between respective shoulders
136 thereof.
In this example, a collar 138 is further disposed about respective anchoring
structures 134
so to further define the rail load bearing surface, namely in providing for a
direct lateral
contact with the rail once so disposed therebetween. Accordingly, the collar
138 may act
to provide a similar function as that provided by the inner and outer channel
sidewall
abrasion guard portions described above with reference to the embodiments of
Figures 4 to
6. Otherwise, the anchoring structure shoulders 136 may be disposed to abut
directly or
substantially directly against the railseat 118 to directly limit a lateral
travel thereof once
installed therebetween.
[00046] In either configuration, a rail-engagement portion 140 may be
slidingly
engaged (in this embodiment) with the anchoring portion 134 in a pre-assembled
configuration and ready for deployment upon rail installation (i.e. see Figure
8).
[00047] With particular reference to Figure 9, once the crossties 112
have been laid
and the rails 126 disposed thereon between respective clips 130, 132, the rail
engagement
portions 138 and 140 may be laterally slid into position such that a rail-
engaging toe 142
(and toe cap) thereof operatively slides onto the railseat 118 to secure it
into position upon
the crosstie rail load-bearing surface defined between the clips 130, 132.
[00048] The person of ordinary skill in the art will appreciate that
different rail clips
may be used in the present context without departing from the general scope
and nature of
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the present disclosure, namely so as to couple the railseat to a crosstie in
the appropriate
position between the rail clips.
[00049]
Having now generally described the rail assembly in accordance with
different illustrative embodiments, the composite polymer crossties used
therefor may be
fabricated, in some embodiments, according the compositions and methods
disclosed in
United States Patent Application Publication number US 2006/0226247 Al,
published
October 12, 2006 to Abramson, et al. and entitled "Railway Ties and Structural
Elements"
and United States patent number 8,252,216, issued August 28, 2012 to Abramson,
et at.
and entitled "Method for the Production of Railway Ties"; the entire contents
of each one
of which are hereby incorporated herein by reference. Other compositions and
methods
wherein a composite polymer crosstie beyond those disclosed in the
abovementioned
documents may also be suitable and accordingly the instant disclosure should
not be
limited thereto. Accordingly, the composite polymer crosstie may be
fabricated, in some
embodiments, from a composition comprising at least an asphaltic component, a
polymeric composition component and a strengthening agent. Furthermore, in
some
embodiments, the strengthening agent may be fibres which are pre-included in
the input
polymeric component. Additionally, the fibres may be included, in some
embodiments, in
the starting mix pre-included in the polymeric component. The fibres may, in
some
embodiments, be glass fibres.
Exemplary Crosstie Compositions and Fabrication Methods
[00050] By
way of example only, the composite polymer crossties comprise an
asphalt component, a polymeric composition component and a strengthening agent
component pre-included in the polymeric component (thus forming a fiber-
reinforced
1 024P-RTC-CADI 18
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plastics component) and optionally plastics chosen from the group consisting
of virgin
plastics, recycled plastics, and combinations and mixtures thereof. Also, as
noted above, in
some embodiments, the composite polymeric crossties comprise an asphalt
component, a
polymeric composition component and a strengthening agent component which is
not pre-
included in the polymeric component. In some embodiments, the asphalt
component
comprises between 15% and 95%, by weight of the composite polymer crossties
and the
total polymeric component content comprises between 5 and 85% by weight of the
crosstie. It should be noted that although a minor amount of impurities may be
present in
the starting materials, such as moisture, the effect on the manufacturing
process of the
composite structural element is negligible.
1000511 In preferred embodiments, the asphalt component comprises about
65% to
85% by weight of the total weight of a given composite polymer crosstie. More
preferably,
the asphalt component, in some embodiments comprises about 70% to 80% by
weight of
the total weight of the composite polymer crosstie. Preferably, the total
polymeric
component comprises about 10% to 45% by weight of the total weight of the
composite
polymer crosstie. More preferably, in some embodiments, the total polymeric
component
comprises about 15% to 40% by weight of the total weight of the composite
polymer
crossties. Even more preferably, the total polymeric component comprises about
20% to
30% by weight of the total weight of the composite polymer crossties.
1000521 The fiber-reinforced plastics component, in some embodiments
comprises
between about 25% and 75% by weight of the total polymeric component content.
In some
embodiments, the fiber-reinforced plastics preferably comprises between about
30% and
70% by weight of the total polymeric component content. However, in most
preferred
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embodiments, the fiber-reinforced plastics component comprises between about
40% and
60% by weight of the total plastics component content. In some embodiments,
the
composite polymer crossties are formed from about 75% of an asphalt component,
about
11% of a glass fiber-reinforced polypropylene component and about 14% of a
high-
density polyethylene component.
[00053] While the composite polymer crossties are typically formed from
an asphalt
component, fiber-reinforced plastics and other plastics, the composite polymer
crossties of
the instant disclosure may further comprise an elastomer in a proportion of
about 0 to 80%
by weight. Preferably, the elastomer comprises between 0 and 30% by weight of
the
composite polymer crosstie.
[00054] Typically, asphalt used in the composite polymer crosstie of
the instant
disclosure is recycled asphalt that has been crushed and subsequently screened
for size.
For example, the asphalt component is typically passed through a series of
screens having
progressively smaller square openings. Larger asphalt particles are caught in
the first
screens while finer particles are caught by later screens. In some
embodiments, for
example, greater than about 75% of the asphalt is able to pass through a
screen having
0.75 inch square openings. However, in preferred embodiments, at least 50% of
the
asphalt is able to pass through a screen having 0.5-inch square openings. For
example,
suitable fines of asphalt material for use have a size from 1/4" to about
1/4", which are
readily available from asphalt manufacturers.
[00055] Polymeric materials suitable for use in composite polymer
crossties of the
instantly disclosed system may be chosen from, for example, low-density
polyethylene
(LDPE), high-density polyethylene (HDPE), and polypropylene (PP).
Additionally,
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although virgin polymeric materials or, in other words, virgin plastics
materials, may be
used to form the composite polymer crossties, in some embodiments it may be
preferable
to use recycled plastics materials so as to reduce the amount of waste in our
environment.
Such recycled plastics materials may be polymeric materials such as, for
example,
polyvinyl chloride (PVC), low-density polyethylene (LDPE), high-density
polyethylene
(HDPE), polypropylene (PP), polystyrene (PS), polyethylene terephthalate
(PET), and
combinations and mixtures thereof.
[00056] The polymeric material component, in some embodiments, is
prepared for
incorporation into the composite polymer crosstie during the manufacturing
process of the
composite polymer crossties, by aligning the mesh sizing with that noted above
for the
asphalt component or smaller. The polymeric component may also be sized as
required by
pelletizing, grinding or flaking or otherwise provided at a suitable particle
size.
100057] The polymeric component, when provided as a fibre-reinforced
plastics
component, may be, for example glass-filled polypropylene with a pre-
determined
proportion of glass fibres. Such a material is readily available commercially
and as a
recycled material where the glass is intertwined with the polypropylene and is
continuous
throughout the polypropylene component. Embodiments utilizing glass-filled
polypropylene are preferred as the inclusion of the glass fibres enhances the
strength of the
composite polymer crosstie. Other fibers (such as carbon fibers or silicon
fibers) may also
be utilized in various embodiments to reinforce the polymeric component and
thus the
composite polymeric crossties.
1000581 In addition to the asphalt component, the fiber-reinforced
polymeric
components and other plastics materials, the composite polymer crossties in
some
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embodiments may further comprise an elastomer. The elastomer is preferably
tire rubber
that has been recycled from sources such as scrap tires. In such embodiments,
at least
about 75% of the elastomer is able to pass through a screen mesh having 0.25-
inch square
openings. However in preferred embodiments, at least about 75% of the
elastomer is able
to pass through a screen mesh having 0.125-inch square openings.
[00059] Furthermore, in some embodiments, the composite polymer
crossties may
be made from more than one composition. For example, a first portion and a
second
portion. The first portion and the second portion comprise the asphalt
component, the
polymer component and the strengthening agent as described above. However, the
first
portion may comprise from about 15% to 75% asphaltic component and from about
85%
to 25% of a first polymeric component, and optionally a strengthening agent.
In some
embodiments, the first polymeric component comprises about 50% of a plastics
material
and about 50% of a glass fibre-filled recyclable thermoplastic material, such
as a glass
fibre-filled polypropylene, acting as the strengthening agent. In such
embodiments, the
second portion may comprise from about 20% to about 85% by weight of an
asphaltic
component and from about 15% to about 80% by weight of a second polymeric
component, and optionally a strengthening agent. In some embodiments, the
second
polymeric component comprises a glass fibre-filled recyclable thermoplastic
material as a
strengthening agent.
[00060] Briefly, composite polymer crossties may be manufactured utilizing
the
first and second portions noted above according to the method as disclosed in
U.S. Patent
number 8,252,216. For example, the first and second portions may be separately
prepared
and blended. The first and second portions are then separately heated to a
temperature
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suitable to at least melt a portion the polymeric component and then processed
in
processors operable to heat and feed said blends separately as composite
asphalt plastic
compositions to pump means associated with a co-extrusion die. The heated and
pliable
first portion is then pumped into a first section of a mold to form a core
portion of the
composite polymer crosstie, and the heated and pliable second portion is
simultaneously
pumped into an outer portion of the mold to form the outer portion of the
composite
polymer crosstie. However, in some embodiments, it may be preferable to
reverse the
order such that the second portion is used to form the core and the first
portion is used to
form the outer portion.
TESTING EXAMPLES
[00061] Composite polymer crossties produced from compositions as noted
above
were tested to determine if composite polymer crossties for use in the
instantly disclosed
system met the specifications laid out in Section 5.3.3., Chapter 30, Part 5
of AREMA
(American Railway Engineering and Maintenance-of-Way Association) manual
(2012)
regarding Engineered Composite Ties. Briefly, a composite polymer crosstie
suitable for
use in railway systems must meet the mechanical and performance requirements
set forth
in Table 30-5-1 of the abovementioned section AREMA manual. The laboratory
testing
was therefore performed in accordance with the specific elements set forth in
Chapter 30,
Part 2, and entitled "Evaluative Tests for Tie Systems".
[00062] The subject composite polymer crossties each weighting
approximately 350
lbs., having dimensions of about 102 inches in length and cross-sectional
dimensions of
about 7 inches by 9 inches were tested. The rails were coupled to the
composite polymer
crossties using generic 1:20 cant intervening tie plates with a contact
surface area
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substantially matching of the railseat anchored to the crosstie surface using
screw-spikes
and PandrolTm-type E2055 rail clips were used to couple the rails to the
generic tie plates.
It should be noted that such tie plates used to couple the rails to the
crossties are not
considered to "force-distributing" as they do not substantially increase the
surface where
downward force from the rail is applied to the crosstie. Such tie plates
coupled to the
crossties are used as intervening anchoring points for the clips. Holes for
receiving therein
the screw-spikes were pre-drilled where the fastener location was countersunk
to
accommodate the unthreaded portion of the screw-spike and the remainder of the
hole was
drilled at a smaller diameter for fixture of the threaded portion of the screw-
spike to the
crosstie. The smaller diameter portion of the hole was drilled through and
exposed on the
opposing side of the crosstie.
Rail/Plate Area Compression Test
[00063] This test was performed to determine the ability of the
crossties to resist
railseat loads. Briefly, the test consists of applying a vertical load on a
pre-determined
area. There are two methods which were used in testing the composite polymer
crossties
of the instant disclosure. In any and all cases, the maximum elastic
deformation while
under load should not exceed 1/4-inch, with permanent deformation after
release of the
compressive force not exceeding 1/8-inch within 1 minute of releasing the
load. The first
method uses the rail itself (i.e. devoid a force-distributing plate) having a
surface area
contacting the composition polymer crosstie of 5 1/2 inches by 9 inches. The
second
method uses a force-distributing plate having a surface area contacting the
rail of 7 1/4
inches by 14 inches. A pressure, according to the test parameters, was applied
at 900 psi
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(44,550 lbs.) for the rail only first method and 921 psi (100,000 lbs.) for
the force-
distributing plate second method.
[00064] The results of the Rail/Plate Compression Test are as follows:
Table 1
Sample Tie Pressure Applied Max.
Deflection Deflection (psi) (1
(psi) (inch) min. @ 0 psi)
#1 - Method 1 (Rail 900 0.165 0.003
Compression)
#2 - Method 2 (Plate 921 0.193 0.005
Compression)
[00065] According to the AREMA testing parameters, the pass/fail
requirements are
set at 0.250 inch for max deflection and 0.125 inch for residual deflection.
As clearly
shown in Table 1 above, the composite polymer crossties and system disclosed
herein
passed the test. Additionally, in the long term, there was no evidence of
permanent
deflection. The tester also noted that upon removal of the compression device,
the top
surface of the composite polymer crossties were in pristine condition and this
was
achieved without the aid of any protective pad or interim force-distributing
plate of any
kind.
Embedded Screw/Spike/ Pull-out Test
[00066] This test was performed to determine the ability of the crossties
to resist
withdrawal of the rail fastening system (spikes). In conducting this test a 6
1/2-inch long
spike is inserted 4 1/2-inches into the composite polymer crosstie. A pull-out
load was
applied at 1 inch per minute and a minimum extraction load of 5,000 lbsf
(pound force) is
required to pass the test.
[00067] The results of the Embedded Screw/Spike/ Pull-out Test are as
follows:
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Table 2
Sample Tie Extraction Load (lbsf)
#1 15,890
#2 17,300
1000681 As noted above the pass/fail requirement for this test is a
minimum extraction
pull-out load of 5,000 lbsf. As show in Table 2, both sample composite polymer
crossties
passed the Embedded Screw/Spike/Threaded Insert Pull-out test and generated
values of at
least three times the required minimum.
Spike Lateral Restraint Test
[00069] The Spike Lateral Restraint Test was performed to determine the
ability of a
screw-spike to resist lateral movement. Briefly, the spike is driven in the
tie to a normal
working depth and a load is applied laterally to 0.2-inch at a rate of 0.2-
inch per minute. A
load/deflection curve is then generated and a maximum load is recorded. It
should be
noted, that there is no pass/fail criteria provided for AREMA for this test.
1000701 The results of the Spike Lateral Restraint Test are as follows:
Table 3
Sample Tie Load g 0.2 inch
displacement
#1 3715
#2 3891
Tie and Fastener System Wear-Deterioration Test
The Tie and Fastener System Wear-Deterioration Test was performed to determine
railseat
deterioration and fastener system performance in heavy axle load environments
due to
repeated load. In this test a complete track system is emulated where two
rails are coupled
to the composite polymer crosstie and the crosstie is solidly fixed to the
test bed. This
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testing was preformed using standardly shaped polymer crossties of the
compositional
embodiments discussed above devoid of the rectangular channel noted above in
one set of
tests (noted below as example Tie and Fastener System Wear-Deterioration Test
1) and in
another set of tests using polymer crossties of the compositional embodiments
discussed
above having the rectangular channel milled in the top surface for receiving
the railseat
therein (noted below as example Tie and Fastener System Wear-Deterioration
Test 2).
[00071] Briefly, the testing machine comprises a load frame with a servo-
controlled
dual action hydraulic actuator. The test load is distributed through to load
arm set at an
angle of 27.5 degrees from vertical. The load is transmitted equally to each
of the two
railheads of a full crosstie using the appropriate fastening system. A load of
65,000 lbsf
was cyclically applied to the set-up, for a lateral top vertical ratio of
0.52. An abrasive
environment must also be simulated on each rail seat for this test.
Accordingly, water drip
nozzles were positioned over the field and gauge sides of each railseat. Clean
and dry sand
was also spread on both sides of the railseat.
[00072] To measure static and dynamic lateral head displacement during the
test, a
displacement meter was placed behind the railhead and railbase on each
railseat.
Deflections were monitored at regular intervals (500,000 cycles minimum) and
tracked
throughout the test to ensure that there was no excessive movement.
[00073] After completing the pre-test procedures, a head measurement
under static
load was taken to establish a benchmark. After completing the static load
measurement,
the wear/abrasion test was initiated and under normal conditions is for either
3,000,000
cycles, or until failure, at a frequency of 2.8 Hz. Any abnormalities were
noted. Upon
completion of the wear/deterioration test, the rail seat assemblies were
examined and
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photographed. The static load test was then repeated. The dismantled
components were
then examined for sign of failure/damage and the rail seat deterioration
maximum depths,
if present, were measured.
[00074] In order to pass the test, no deflection during the test should
exceed 0.2000
inches and none of the actual components under test (in this case the
composite polymer
crosstie) should fail.
TIE AND FASTENER SYSTEM WEAR-DETERIORATION TEST 1
[00075] The results of the Tie and Fastener System Wear-Deterioration
Test 1 are as
follows. In this set of testing, standardly shaped polymer crossties (i.e.
devoid of a
rectangular channel milled in the top surface for receiving therein the
railseat of a railway
rail) were used (not shown in the figures). The rails were coupled to the
polymer crosstie
using commonly known intervening tie plates which were coupled to polymer
crosstie by
four screw spikes each. Briefly, the rail rests on the tie plate and a pair of
tie clips interact
with the railseat and the tie plate so as to couple the rail to the polymer
crossties in a
manner commonly known in the art for coupling railway rails to wooden
crossties. The
test, as noted above, was to be run for at least 3,000,000 cycles with close
monitoring of
the components for signs of breakage (failure) of a given component and/or
head lateral
displacement of the railhead in excess of 0.200 inch, which would represent a
fail.
[00076] During the test two notable events occurred. Firstly, at
1,423,000 cycles one
of the tie plates broke (Tie Plate B) at the shoulder and therefore allowed
for rotation of
the rail. Since the composite polymer crosstie being tested did not fail, the
broken tie plate
was changed and the testing resumed. Secondly, at 2,675,00 cycles the tie
plate in the
same position as the previous broken tie plate failed and again, allowed for
rotation of the
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rail. This second broken tie plate was changed and the testing continued.
These breakage
points, and leading up to the failure, can be clearly seen in the lateral head
displacement
data present in Table 4, below.
[00077] At the completion of the testing, the components were assessed
and the
following observations were made.
[00078] Tie Plates ¨ Tie plate A showed no signs of fatigue fissuring
and was used
throughout the test. As noted above, tie plate at position B required two
changes and the
cause of the failure was unknown.
[00079] Rail Clips - All four rail clips performed well and no signs of
permanent
deformation where observed.
[00080] Screw-spikes ¨ No damage or signs of failure were noted with the
screw-
spikes. Even the spikes that were re-driven with respect to the tie plate
changes at position
B performed well.
[00081] Composite -Polymer Crossties ¨ The composite polymer crosstie
was
examined for signs of wear and deterioration. It is interesting and surprising
to note that,
unlike wooden crossties, the surface of the composite polymer crosstie showed
virtually
no signs of abrasion after the fatigue test. The section under the tie plate
which was not
directly under the rail was noted by the tester to be "pristine", thus edges
of the tie plates
did not dig into the top surface of the composite polymer crossties
whatsoever. Reference
lines drawn on the composite polymer crosstie to center the tie plates were
still visible
after the testing. No pitting or abrasion marks were measured at any location
on the tie.
Therefore the composite polymer crossties as disclosed herein have wear
characteristics
equal to or better than concrete crossties, which are significantly more
expensive to
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manufacture. In order to obtain such wear characteristics with concrete
crossties, a cushion
mat is required which was not used in the testing of the instant composite
polymer
crossties.
[00082] The
composite polymer material from which the crossties were fabricated
created a thread pattern for the spikes which was extremely effective at
holding said spikes
even when "re-spiked" to change the broken tie plate, noted above. Unlike in
the
maintenance of conventional wooden (and in some instance concrete) crossties
no filler or
epoxy was used in the re-driving of the screw-spikes and the system did not
show any
signs of a reduction in the retention properties of the screw-spikes in the
composite
polymer crosstie - thus showing a significant improvement over the
characteristics of
conventional wooden crossties. This surprising property of the composite
polymer
crossties disclosed herein is shown with respect the to the lateral head
displacement values
noted below in Table 4.
Table 4
Number of Seat A Seat A Seat B Seat B
Cycles Railhead Railbase Railhead Railbase
Static Before 0.067 0.017 0.077 0.006
8,000 0.046 0.011 0.046 0.004
50,000 0.046 0.011 0.049 0.006
300,000 0.046 0.009 0.045 0.004
500,000 0.047 0.008 0.045 0.003
800,000 0.049 0.009 0.044 0.003
1,100,000 0.048 0.009 0.058 0.007
1,423,000' 0.052 0.009 0.074 0.003
1,425,000b 0.049 0.009 0.049 0.004
1,700,000 0.049 0.008 0.048 0.006
2,100,000 0.049 0.008 0.048 0.005
2,500,000 0.049 0.008 0.68 0.010
2,675,000e 0.050 0.008 0.075 0.008
2,765,000d 0.052 0.007 0.040 0.008
2,929,000 0.049 0.008 0.043 0.007
Static After 0.055 0.013 0.058 0.013
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a: Before, but close to the above-noted first tie plate failure
b: After the above-noted first tie plate failure
c: Before, but close to the above-noted second tie plate failure
d: After the above-noted second tie plate failure
[00083] As shown in Table 4, the lateral head displacement values for
the Static
Railhead displacement either maintained initial values or actually decreased
with usage
(Static deflection for Seat A Railhead before = 0.067 initial reading vs.
Static deflection
for Seat A Railhead after = 0.055; Static deflection for Seat B Railhead
before = 0.077 vs.
Static deflection for Seat B Railhead after = 0.058), unlike with wooden or
other
conventionally used crossties. Therefore, the spikes, when used in the
instantly disclosed
composite polymer crossties either maintain a consistently low deflection
value or in fact
tighten, as opposed to loosening as is seen and problematic in conventional
crossties, by
virtue their composition.
[00084] With respect to the above testing of the composite polymer
crossties used in
the instantly disclosed system, it was surprisingly discovered that the
holding properties of
the crossties for the screw-spikes were noted to be exceptional as compared to
conventional wooden crossties. The holding properties of a given crosstie are
correlated
through the lateral head displacement measurements. For example, with the use
of
conventional wooden crossties one would expect both higher initial lateral
head
displacement values and a higher increase in deflection values as the crosstie
progressed
through the test, which as observed by the data of Table 4, is clearly not the
case with use
of the instantly disclosed system. The lateral head displacement values of the
instantly
disclosed system remained substantially constant throughout the testing.
Furthermore, as
no cushion mats or surface-area-increasing force-distributing plates were used
in the
testing, it was shown that the instantly disclosed system does not require the
use of
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cushion mats that may erode to surpass the wear properties od wooden
crossties. Also, the
abrasion normally suffered by conventionally used wooden crossties was not
observed. As
noted above, following the test, no abrasion of the composite polymer
crossties was seen
in the area contacted by the tie plate/rail.
[00085] Additionally, surprisingly, with reference to Table 4, even when
the Tie Plate
B suffered catastrophic failure at 1,423,000 and 2,675,000 cycles,
respectively, only a
marginal increase in the lateral head displacement values were observed. This
indicates
that the instantly disclosed system may be capable of continuing to function
for a
significant number of cycles (or train passes) even with a broken tie plate.
Therefore, an
-- improved safety aspect may be provided by the instantly disclosed system.
TIE AND FASTENER SYSTEM WEAR-DETERIORATION TEST 2
1000861 The results of the Tie and Fastener System Wear-Deterioration
Test 2 are as
follows. In this set of testing, polymer crossties having a rectangular
channel milled into
the top surface for receiving therein the railseat of a railway rail were used
as is shown, for
-- example in Figures la to lc and the assembly as shown in Figures 2a to 3b.
No abrasion
guards in the rectangular channel where employed in this testing. The test, as
noted above
was to be run for at least 3,000,000 cycles with close monitoring of the
components for
signs of breakage (failure) of any components and/or head lateral displacement
of the
railhead in excess of 0.200 inch.
[00087] At 2,841,634 cycles it was noted that in a side of the rectangular
channel
outward (Seat A Railbase) in the direction of force from a load arm (i.e. the
field-side of
the railseat and rectangular channel), that the railseat had become embedded
in the
polymer tie material and the test was stopped.
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[00088] Following the completion of the testing, it was noted that all
four of the rail
clips performed well and showed no sign of permanent deformation aside from
expected
abrasion marks at expected points. Additionally, the screw spikes showed no
signs if
unusual wear or abrasion, however the spike located nearest the point where
the railseat
had become embedded in the polymer tie material was noted to have less
resistance when
removed compared to other spikes. The polymer crossties were observed to be
overall
structurally sound. No cracking or permanent bending was apparent at any point
on the
polymer crossties.
[00089] Surprisingly, contrary to that commonly seen in wooden
crossties, the
rectangular channel, created by the milling in the top surface, did not show
any signs of
abrasion. Therefore, using the polymer crossties with a rectangular channel
and system as
described herein may maintain toe load by the rail clip compared to
conventional wooden
crossties and also such a system appears to be resistant to a gap being foimed
between the
bottom of the railway rail and the crosstie as is a known problem with wooden
crossties.
Additionally, in the instantly disclosed system, no cushion mats are located
between the
railseat and the crosstie as are used with concrete crossties. These cushion
mats are known
to flatten and deteriorate where, similar to wooden crossties, a gap begins to
forms
between the bottom of the railway rail and the crosstie as the cushion mats
deteriorate.
[00090] With exception of the spike located nearest the point where the
railseat had
become embedded in the polymer tie materials, the remaining screw spikes
retained their
high torque values and the system performed very evenly, without losing any
retention
properties of the screw spikes. The instantly disclosed system, compared to
conventional
1024P-RTC-CAD1 33
CA 02852525 2014-05-15
wooden crossties, was extremely efficient in holding and maintaining the screw
spikes
through out the test.
1000911 The
results of the nominal head and base displacements as a function of the
number of cycles for Tie and Fastener System Wear-Deterioration Test 2 are
shown below
-- in Table 5.
Table 5
Number of Seat A Seat A Seat B Seat B
Cycles Railhead Railbase Railhead Railbase
Static Before 0.095 0.007 0.098 0.018
500 0.052 0.002 0.054 0.005
282,000 0.052 0.003 0.048 0.001
644,000 0.052 0.004 0.049 0.005
950,000 0.052 0.004 0.049 0.005
1,250,000 0.056 0.005 0.050 0.005
1,550,000 0.058 0.005 0.050 0.005
1,850,000 0.068 0.006 0.051 0.005
2,082,000 0.070 0.006 0.051 0.005
2,149,000 0.072 0.005 0.052 0.005
2,456,000 0.078 0.006 0.053 0.005
2,674,000 0.081 0.007 0.051 0.005
2,748,000 0.081 0.007 0.050 0.005
2,841,634 N/A*(>0.063) 0.008 0.050 0.004
Static After N/A N/A N/A N/A
* No value is available because the transducer had reached its physical limit
(extension)
when acquiring a max value.
1000921
Therefore, using the instantly disclosed system wherein no tie plates or
cushion mats are utilized and the polymer crossties have a rectangular channel
for
receiving therein the railseat of a railway rail, consistent head displacement
values in the
0.050 inch range were observed (Seat B Railhead of Table 5). The values
returned for Seat
-- A Railhead beginning around 1,550,000 cycles can be attributed to test
design and the
railseat embedding in the side of the rectangular channel outward in the
direction of force
from a load arm as discussed above. Accordingly, in some embodiments, an
abrasion
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CA 02852525 2014-05-15
guard may be applied in the rectangular channel, as discussed in more detail
above to
prevent the railseat from embedding in the side walls and thus protect the
rectangular
channel.
[00093] Compared to conventional wooden crosstie rail coupling systems
and the
system tested in Tie and Fastener System Wear-Deterioration Test 1, the system
of Tie and
Fastener System Wear-Deterioration Test 2 utilizes only 2 screw spikes per
coupling of
the railseat to the polymer crosstie, as opposed to 4. Additionally, as noted
above, no tie
plates or cushion mats were utilized in Tie and Fastener System Wear-
Deterioration Test
2. Surprisingly, using the system described in Tie and Fastener System Wear-
Deterioration
Test 2 and shown in the figures, the results showed that the polymer crossties
of the instant
disclosure and the system of Tie and Fastener System Wear-Deterioration Test 2
were
comparable to the Tie and Fastener System Wear-Deterioration Test 1.
[00094] It is to be understood that the above description it is intended
to be
illustrative, and not restrictive. Many other embodiments will be apparent to
those skilled
in the art, upon reviewing the above description. The scope of the invention
should,
therefore, be determined with reference to the appended claims, along with the
full scope
of equivalents to which such claims are entitled.
[00095] Although the present invention has been described with reference
to specific
exemplary embodiments, it will be evident that various modifications and
changes may be
made to these embodiments without departing from the broader spirit and scope
of the
disclosed subject matter as defined by the appended claims.
1024P-RTC-CADI 35
