Note: Descriptions are shown in the official language in which they were submitted.
CA 02737344 2013-08-26
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STRIKE ATTACHMENT RAILROAD ANCHOR
FIELD
The present disclosure relates to a friction clamp system that allows for
connecting objects to a railroad track rail and/or for forming an electrical
connection
between such a track rail and an electrical conductor.
BACKGROUND
In railroad applications, it is often desirable to attach one or more
components
to the track rail. A non-inclusive list of such components includes
communications
wires (i.e., signal conductors) and track heaters. In the latter case, such
track heaters
are often utilized in cold weather climates at railroad switches.
Components are often anchored directly to the track rail utilizing bolts
and/or
welds. In this regard, a hole may be drilled into the track rail for mounting
purposes,
or, a portion of the component may be welded directly to the track rail. Such
interconnection techniques are generally labor intensive and require careful
positioning to prevent structurally weakening the track rail. Such connection
techniques can result in a stress concentration within the track rail.
Further, the heat
of exothermic connectors (welding) can result in a brittleness in the track
rail. As will
be appreciated, track rails are subjected to repeated heavy loading (e.g.,
railroad
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traffic) and areas including such stress concentrations and/or brittleness may
be
subject to failure.
SUMMARY
One objective of the present is to provide a coupling that may be quickly and
securely attached to a track rail to support one or more components relative
to the
track rail. A further objective is to provide a coupling for maintaining the
relative
position of a track rail to an underlying tie. These and/or other objectives
may be
accomplished by various systems and methods (i.e., utilities) that utilize a
friction
clamp that securely attaches to a track rail.
A first aspect provides a friction clamp anchor for attachment to a flange of
a
railroad track rail. The clamp includes an elastically deformable U-shaped
body
having an upper member, a lower member and a closed end. The upper and lower
members are disposed in a spaced and opposing relationship (e.g., opposing
members)
that is sized to receive a flange of a railroad track rail. That is, the upper
and lower
members and the closed end define a recess sized to receive the flange of the
railroad
track rail. The upper member includes first and second upper teeth that each
have a
base integrally formed with the upper member and which extends away from its
base
to a gripping tip. The gripping tip extends below the bottom surface of the
upper
member such that it is at least partially disposed within the space between
the
opposing members. Likewise, the lower member has at least a first tooth having
a
gripping tip that extends at least partially into the recess defined between
the opposing
members. At least the tips of these teeth are hardened such that they may
penetrate
the surface of the track rail to provide an effective grip between the rail
and the spring
clamp. Finally, the anchor includes an attachment point for attaching an
object to the
clamp and/or engaging the clamp with a railroad structure.
The anchor may be designed in any manner that allows the opposing members
to engage opposing surfaces of the track rail. In one arrangement, the
opposing
members are formed from a metal plate that is formed into the U-shaped body.
Typically, the spacing between the opposing members is such that a portion of
the
track rail, such as the flange, may be disposed within this recess defined by
the
opposing members. This recess may be tapered. Accordingly, by driving a
portion of
the track rail into the tapered recess the opposing members be deflected from
a static
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position. In one arrangement, the opposing members are spaced between about 1
cm
and 4 cm centimeters apart. In this regard, the opposing members are adapted
to
receive the flange of most track rails. However, it will be appreciated that
other
arrangements are possible.
In order to maintain the anchor on the track rail, the opposing members each
may include one or more teeth that are operative to engage the surface of the
track
rail. These teeth may have a hardness that is greater than the hardness of the
track rail
to facilitate engagement therewith and marring of the track rail surface to
form an
electrical connection. In one arrangement, at least the gripping tip of each
tooth has a
Rockwall hardness that is greater than about 40 and more typically greater
than about
60. Such teeth may be separately formed and interconnected to the opposing
members, or the teeth may be integrally formed within the opposing members.
In one arrangement, the teeth are formed from a plate member that is utilized
to form the U-shaped body. In such an arrangement, the base of each tooth may
be
integrally formed with the plate member of the U-shaped body and may extend to
its
gripping tip. This gripping tip may be formed by the edge surfaces of the
plate. In
one arrangement, two edge surfaces form the tip where an included angle
between the
edge surfaces is acute. More preferably, such an included angle is less than
about 60 .
This results in a tooth gripping tip that is sharp enough to engage and mar
the surface
of a track rail flange in order to generate an effective connection therewith.
For
instance, such a tooth may be formed of two adjacent edge surfaces of a plate
member
having a thickness of at least about 3/16th of an inch and an included angle
of about
60 or less. This may provide a sharp point for penetrating the outer surface
of a track
rail.
In one arrangement, the upper member and/or the lower member may have
first and second opposing teeth. In one arrangement, each such opposing tooth
may
extend laterally from the edges of its respective member of a common location
along
the length of the member. That is, the opposing teeth may be aligned at a
common
axial location relative to a centerline of the clamp. This opposing
relationship helps
cancel lateral forces applied to the anchor and makes the anchor extremely
resistant to
lateral movement. To permit partially independent movement of such teeth, each
tooth may define a cantilevered member that may flex along its length.
Furthermore,
to improve movement between teeth interconnected to opposing sides of the
upper or
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lower members, the member may include an aperture disposed through its surface
that
is located at least partially between the bases of such teeth. This may permit
one
tooth to flex (e.g., twist) free of an opposing tooth.
In one arrangement, the tips the teeth connected to a common member (e.g.,
upper member or lower member) are coplanar at least prior to application to a
track
rail. In this regard, when applied to a track rail, these coplanar gripping
tips may
engage at multiple separate locations on the track rail. Further, when these
teeth are
cantilevered, they may flex to permit each tooth to engage the rail surface.
In one
arrangement, the teeth are backward swept to resist the removal of the spring
clamp
from a flange. In this regard, the gripping tip of one or more of the teeth
interconnected to the upper and/or lower members may, between its tip and
base,
point in a direction towards the closed end of the U-shaped body.
In a further arrangement, one or more spring tabs may be interconnected to the
closed end of the U-shaped member to facilitate the positioning of the U-
shaped
member relative to the flange. Such spring tabs may extend from a base
interconnected to and/or integral with the closed end of the U-shaped body to
a tip
that is disposed at least partially within the recess defined by the U-shaped
body.
In a further arrangement, the U-shaped member may include a galvanic
coating. Such a galvanic coating may include a hot dipped galvanization
coating.
Other non-corrosive coatings and/or sacrificial coating may be utilized as
well. These
coatings include, without limitation, nickel coatings/plating, elastomeric
coatings etc.
In another aspect, a method for forming an anchor for use with a track rail is
provided. The method includes die stamping a substantially flat metal plate to
define
a flat anchor body having at least one tooth proximate to a first end of the
body and at
least one tooth proximate to a second end of the flat body. In such an
arrangement,
the base of each tooth is integrally formed with the flat body. Once the
anchor body
and integrally defined teeth are stamped, each tooth may be bent such that the
tip of
the tooth is raised above the surface of the flat anchor body. The flat anchor
body
may then be bent into U-shaped where the first and second ends of the body are
disposed in a spaced and opposing relationship. In such an arrangement, the
tips of
the teeth interconnected to the first and second ends may extend partially
into a recess
defined between the opposing ends. The tips of one or all the teeth may be
hardened
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to provide a hardness that is in excess of the track rails to which they are
intended to
be connected.
BRIEF DESCRIPTION OF THE DRAWINGS
For a more complete understanding of the present invention and further
advantages thereof, reference is now made to the following Detailed
Description
taken in conjunction with the drawings in which:
Fig. 1 shows a section of railroad track rails.
Fig. 2 shows a perspective view of a connector that may be utilized to
electrically interconnect adjacent sections of track rails.
Fig. 3 shows a front perspective view of the connector of Fig. 2.
Figs. 4A-4D shows various views of one embodiment of a spring clamp.
Fig. 5 shows a side view of the spring claim of Figs. 4A-4D and 6A -6B as
applied to a flange of a track rail.
Figs. 6A-6B show perspective and side views of another embodiment of a
spring clamp.
Fig. 7 illustrates a further embodiment of a spring clamp.
Fig. 8 illustrates a yet further embodiment of a spring clamp.
Fig. 9 illustrates utilizing the spring clamp to hold a component relative to
track rail.
Figs. 10A and 10B illustrate a further embodiment of a spring clamp anchor.
Figs. 11A and 118 illustrate the penetration of the gripping tips of the
spring
clamp anchor.
DETAILED DESCRIPTION
Provided herein are various embodiments of a friction clamp connector for
attaching components to a railroad track rail and/or electrically connecting a
signal
conductor to a railroad track rail.
Referring to Fig. 1, a section of railroad track is generally identified by
the
reference numeral 10. As shown, the section of railroad track 10 includes a
switching
mechanism to switch trains between first and second tracks 12, 14. Each set of
tracks
12, 14 includes two of track rails. As shown, the first track 12 includes a
switching
rail 12a and a stationary or stock rail 12b (also known as a running rail).
Likewise,
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the second track 14 includes a stock rail 14a and a switching rail 14b. For
purposes of
controlling traffic, each track rail 12, 14 is electrically interconnected to
a signal
providing and monitoring system 8 that is located in proximity to the rail
connection
location
The signal providing and monitoring system 8 is operative to redirect trains
from the first track 12 to the second track 14 by mechanically moving the
switching
rails 12a and 14b relative to the stock rails 12b and 14a, respectively.
Generally, a
switch mechanism is mechanically interconnected to the switching rails 12a and
14b
in order to move them in unison relative to the stock rails 12b and 14a at the
connection point. The switching mechanism is typically attached to the rails
with an
electrically isolated linkage. In the case of switching rail 14b, mechanical
movement
may occur on both ends. That is, a first end of the switching rail 14b may be
moved
relative to the stock rail 12b and a second end of the switching rail 14b may
be moved
relative to a distal portion of switching rail 12a, where these rails cross.
This point is
sometimes referred to as a railroad "frog" 15. The frog 15 may in some
instances be a
passive spring actuated system that utilizes the pressure from the wheels of a
passing
railroad vehicle to permit railroad vehicle wheels to access the correct
track.
Alternatively, the frog 15 may be mechanically actuated/moved to permit
railroad
vehicle wheels to access the correct track. To effectuate switching of the
switching
rails and/or the railroad frog, the monitoring system 8 may detect the
presence of
approaching railroad vehicles and/or receive signals from approaching
vehicles.
In a common arrangement, the signal providing and monitoring system 8
utilizes the track rails 12a, 12b and 14a, 14b to detect the presence and,
generally, the
speed of approaching railroad vehicles and/or to receive signals from the
approaching
railroad vehicles. In this regard, each set of track rails 12, 14 forms an
electric circuit
(i.e., track circuit) that is interconnected to the monitoring system 8 by one
or more
signal lines 16. In one arrangement, a resulting electrical circuit may be
short
circuited when the wheels and axle of an approaching railroad vehicle
interconnects
the track rails 12a, 12b or 14a, 14b. In another arrangement, the impedance of
a
signal changes due to the presence of an approaching railroad vehicle. The
length of
each track circuit depends upon various circumstances including the distance
over
which signals may be effectively sent, received and/or detected. Normally,
such a
track circuit will fall into the range of several feet to a few miles. To
define such
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track circuits, the track rails may be divided into adjacent sections by
providing
insulated joints. Such insulated joints allow for electrically isolating
adjacent sections
to track rail from one another.
Electrically interconnecting any device to a track rail and/or connecting
adjacent track rails generally requires interconnecting an electrical
conductor
(hereafter signal line or cable) to the structure of a given track rail 12,
14. Figs. 2 and
3 show an embodiment of a non-invasive signal line connector 100. As shown in
Fig.
2, the signal line connector 100 attaches a signal line 16 to the surfaces of
immediately adjacent track rails 40a and 40b to make electrical contact
therebetween.
Though illustrated as connecting immediately adjacent track rails it will be
appreciated that aspects of the connector discussed herein may be utilized to
connect a
single-track rail to other electrical devices. In this regard, it will be
appreciated that
the signal line 16 of the connector 100 can be of any appropriate length.
As illustrated in Figs. 2 and 3, the connector 100 is designed to connect to
the
flanges 42 of adjacent track rails 40a and 40b utilizing a pair of spring
clamps/anchor
50. The spring clamps are interconnected by a signal line/conductor 16. It
will be
appreciated that in other embodiments the connector 100 may include a single
spring
clamp that is attached to one end of the signal line 16. In such an embodiment
the
other end of the signal, line may be attached to any electrical device. The
signal line
16 may include an electrically conductive core (e.g., braided copper wire) and
a
nonconductive coating or sheath. In such an arrangement, a portion of the
nonconductive coating can be removed from the signal line 16 to expose a
portion of
the electrically conductive core for conductive coupling with the spring
clamp. While
variously discussed in relation to forming electrical connections with the
track rail, it
will be appreciated that the spring clamp/anchor 50 may alternatively attach
other
components to the track rail.
In any arrangement, the spring clamps 50 provided herein allow for quickly
and conveniently interconnecting a signal line or other object with a flange
42 of the
track rail 40. As will be described below, each spring clamp 50 can be forced
over a
portion of the track rail flange 42 to form a secure compressive coupling with
the
flange. The friction between teeth of the spring clamp securely grips the
flange and,
in one arrangement, completes an electrical interconnection between the signal
line 16
and the track rail 40.
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With reference to Figs. 4A-5, the spring clamp 50 is described. Generally,
each spring clamp 50 includes a U-shaped body 58 that applies a compressive or
clamping force about opposing portions of the rail flange 42 to secure the
spring
clamp 50 to the track rail 40. The U-shaped body 58 utilizes minimally
invasive teeth
56 to grip the rail and/or form an electrical connection. The spring clamp 50
also
includes an attachment portion 70 that is electrically connectable to the
signal line 16
or provides an attachment point for connecting a component to the anchor.
As shown in Figs. 4A-4D, the body 58 of the spring clamp 50 is a generally U-
shaped member 58 that includes first and second opposing members 52, 54 for
engaging top and bottom surfaces of the flange 42 of the track rail 40 (see,
e.g., Fig.
5). As shown, the first and second opposing members 52, 54 define a receiving
slot
66 (e.g., recess) that is sized to receive the flange 42 of the track rail 40.
See Figs 4D
and 5. The first and second opposing members 52, 54 are connected by a closed
end
68 of the body 58. The U-shaped body 58 provides a bias or compressive (e.g.
spring) force between the first and second opposing members 52, 54 that urges
the
first and second opposing members 52, 54 back toward a static position when
these
members are deflected outwardly from their static position. As such, at least
a portion
of the body 58 is elastically deformable. The term "elastically deformable"
represents
the deformation of a body by an applied stress, wherein the body returns to
its original
shape after the stress is removed.
The U-shaped body 58 may be formed of any material that imparts the desired
elastic properties. That is, the material should provide enough elastic
deformation to
create a resilient spring-like retaining force to hold the U-shaped body 58 on
the
railroad flange 42. The closed end 68 may elastically deform to allow the
first and
second opposing members 52, 54 to slightly spread thereby allowing the flange
to be
inserted therebetween. Once inserted, a resilient retaining force caused by
the elastic
deformation of the body may compress the flange between the first and second
opposing members 52, 54. In one arrangement, the elastically deformable U-
shaped
body is made of a metal plate bent into the U-shape and having a thickness of
at least
about one-eighth of an inch and more preferably of at least about three-
sixteenths of
an inch. In such an arrangement, the facing surfaces (e.g., inside surfaces)
of the
opposing members 52, 54 are substantially planar. However, this is not a
requirement.
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The outside surface of the closed end 68 of the U-shaped body 58 also forms
a strike surface 60 to facilitate disposition of the first and second opposing
members
about the flange 42. For instance, an installer may hit the strike surface 60
(see Fig.
4D) using a hammer or other appropriate device to drive the flange 42 into the
slot 66.
When the flange 42 is disposed within the slot 66, the first and second
opposing
members 52, 54 are slightly forced apart from a static position. This allows
the
opposing members to compress about opposing portions of the flange 42 and
thereby
secure the signal line connector 100 to the track rail.
To further prevent inadvertent disengagement of the first and second opposing
members 52, 54 from the flange 42 and/or to ensure electrical conductivity
between
the signal line connector 100 and the track rail 40, each of the first and
second
opposing members 52, 54 includes at least one tooth 56 that works to grip the
flange.
With reference to Figs. 4A-4D, each tooth 56 is subject to a number of
characterizations. Generally, each tooth 56 has a base 57 that is integrally
formed
with one of the opposing members 52, 54 and a gripping tip 59 extends away
from the
base 57. Between their base 57 and gripping tip 59, each tooth 56 may be bent
relative to the substantially planar surface of the member 52 or 54 to which
it attaches.
See Fig. 4C. This bend is typically between about 5 and about 30 . In this
regard,
gripping tip 59 of a tooth 56 may extend partially into the slot 66 between
the
opposing members 52, 54.
By integrally forming the teeth with the body 58, the clamp 50 may be formed
out of a single piece of metal. For instance, a sheet of metal may be stamped
to define
a flat clamp/anchor having multiple teeth extending from one or more lateral
edges
thereof. As shown in Figure 4C, these teeth may then be bent relative to the
substantially planar surface defined by what becomes the inside opposing
surfaces of
the body 58. At this time, the flat elongate member may be bent into the U-
shape as
illustrated in Figures 4A through 4D. Forming the clamp 50 from a single piece
of
material simplifies the manufacturing thereof.
The gripping tips 59 of the teeth attached to the opposing members 52, 54
have a spacing Li that is less than the spacing L2 between the opposing
members.
Upon forcing the flange 42 is into the recess 66, at least the gripping tips
59 of the
teeth 56 rest on the surface of the track rail. See. Fig. 5. As best
illustrated in Figure
4B, each tooth 56 may also angle backwards from its base 57 to its gripping
tip 59.
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That is, the teeth may be angled such that their tips 59 are disposed towards
the closed
end 68 of the U-shaped body 58. When the spring clamp 50 is disposed onto a
track
rail, such backwards swept teeth 56 are resistant to removal. That is, an
attempt to
pull the spring clamp 50 off of the track rail results in the gripping tips of
these
backwards swept teeth 56 being pulled into the surface of the flange and thus
provides
significant resistance to removal.
After application, the gripping tip 59 of each tooth 56 may rest on the
surface
of the track rail 40. See Fig. 5. However, during application, the reduced
spacing Li
of the gripping tips 59 is such that these tips drag along the surface of the
flange 42.
This may result in one or more of the gripping tips 59 scratching the surface
of the
track rail. This provides a significant benefit in that scaling and/or
oxidation on the
surface of the track rail may be penetrated to provide more effective contact
between
the clamp and track rail and/or electrical contact with the anchor and an
attached
signal line. That is, the gripping tips 59 may mar the surface of the track
rails and
expose metal on the rail to form an electrical connection between the rail and
the
clamp 50. While slightly marring the surface of the track rails, it will be
appreciated,
the location and minimal entry of the teeth into the track rail 40 does not
affect the
structural integrity of the track rail 40.
It may be preferred that the teeth 56 have a hardness in excess of that of the
track rail 40 to allow the teeth 56 to effectively mar and subsequently grip
the track
rail 40. Accordingly, the hardness of the teeth 56 may be greater than the
hardness of
the portion of the track rail 40 to which they are designed to engage (e.g.,
the flange
42). In one embodiment, the teeth 56 have a Rockwell hardness of over about
40. In
another embodiment, the teeth have a Rockwell hardness of about 60 or more.
In one arrangement, the gripping points 59 of the teeth 56 may be made a
different material than of the rest of the spring clamp 50. For example, the
tips of the
teeth 56 may be individually formed and subsequently attached to the spring
clamp 50
(e.g., carbide tips). Alternatively, the gripping tips 59 of the teeth 56 may
be
integrally formed with the spring clamp 50 and subsequently hardened utilizing
any
appropriate hardening method (e.g. flame hardening, induction hardening, case
hardening, etc.). To provide a point that is sharp enough to allow the
gripping tips 59
mar/engage the surface of flange 42 and/or create an effective electrical
connection, it
may be preferably that an included angle of the tooth that defines that tip 59
be an
CA 02737344 2011-04-14
acute angle. In one arrangement, this included angle a is less than about 600
or even
less than about 45 . See Fig. 4B. Use of such a sharp point in conjunction
with a
tooth thickness (e.g., plate thickness) of greater than one-eighth of an inch
or more
preferably three-sixteenths of an inch provides a very robust tooth that has
enough
structural rigidity to bite into the surface of the track rail. That is,
thinner teeth tend
not to have enough internal structure to effectively force the tip of the
tooth into the
hard surface of the track rail.
To reduce the likelihood of corrosion at the interface between the interface
of
the teeth 56 and the exposed metal of the track rail 40, various fluids or
other
substances (e.g. epoxy, oil, grease, sealants, coatings) can be applied near
the junction
of each tooth 56 and the track rail 40. Additionally or alternatively, the
spring clamp
50 may have a sacrificial galvanic coating to prevent corrosion of the
interface
between the teeth and the track rail. In one particular arrangement, the clamp
50 is
hot dipped galvanized. In this arrangement, the zinc coating effectively forms
an
anode, which sacrifices electrons to prevent the underlying metals (e.g.,
teeth and
track rail) from corroding. It is believed that a well coated clamp may
provide years of
protection for the underlying metals in this application. Likewise, it is
believed that
an electrical connection formed by the spring clamp should remain viable for
an
extended period of time and potentially for the lifetime of the track rail.
To further enhance the gripping ability of the connector, it is preferably
that
the various teeth 56 are permitted to move at least partially independently
relative to
one another. That is, slight variations in the configuration of the track rail
and/or
surface imperfections thereof may result in the surface of the track rail not
being
identical between different rails. Accordingly, it is preferable that the
teeth of the
clamp 50 accommodate such imperfections.
To permit independent movement of the teeth, the connector 100 incorporates
laterally extending teeth and/or a relief recess in the top and bottom members
52, 54.
The relief recess 90 in the present embodiment is disposed along a central
axis of the
U-shaped body 58 and extends between opposing pairs of the teeth in the top
and
bottom members, respectively. This relive recess in the present embodiment
extends
entirely through the respective member to provide an aperture. However it will
be
appreciated that the recess need not extend entirely through the member. In
any
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arrangement, the relief recess 90 permits opposing lateral teeth e.g., 56a and
56b as
illustrated in Figure 4B, to flex relative to one another more readily than if
the upper
member 54 were solid between these members. Furthermore, by laterally
extending
outwardly from the lateral edges of the top member 54, these opposing teeth
56a, 56b
form cantilevered members the increased length of which allows for additional
deflection between their tips and their base. The arrows in Fig. 4C illustrate
the
flexural movement of these teeth permitted by the relief aperture 90. The use
of the
laterally extending teeth also increases the area over which the teeth engage
the flange
of the track rail. In this regard, the clamp is more resistant to twisting as
the teeth
provide an increased moment to turning forces.
The relief aperture further allows the front set of teeth 56c and 56d as
illustrated in Figure 4B to flex relative to the rearward set of teeth 56a,
56b about
reference axis A-A' as illustrated in Figure 4b. That is, as the upper member
54 has
less structure between the front set of teeth and the back set of teeth (i.e.,
due to the
relief aperture) than exists between the back set of teeth 56a and 56b and the
closed
end 68 of the clamp, the front set of teeth can independently flex relative to
the back
set of teeth. Though discussed primarily in relation to the top member 54, it
will be
appreciated that the lower member may also include a relief aperture that
allows the
various teeth interconnected thereto to flex in a manner similar to that
discussed
above. In any case, use of such relief apertures and/or laterally
extending/cantilevered
teeth permits independent movement of the teeth such that each tooth may
engage the
surface of the track rail even if the track rail contains surface
imperfection.
While each of the first and second opposing members 52, 54 is shown as
including four teeth 56, more or fewer teeth 56 can be utilized depending upon
the
specific application. Moreover, each tooth 56 can be of other appropriate
shapes and
dimensions and possess other appropriate orientations to effectively grip the
track rail
40. For example, one or more teeth may additionally or alternatively extend
from
facing surfaces of each of the first and second opposing members 52, 54.
Figure 6a and 6b illustrate a further embodiment of a clamp 150 that shares
many of the attributes discussed in relation to the clamp 50 of Figures 1
through 4D.
The primary difference is that this clamp 150 has spring tabs 92, 94 that
extend
laterally outward from the closed end 68 of the U-shaped body 58. Similarly to
the
laterally extending teeth, these spring tabs 92, 94 have a based that is
integrally
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formed with the body 58 and a tip that is designed to engage the track rail.
The
purpose of these spring tabs 92, 94 is not to grip the rail but rather to
limit the
movement of the connector 100 relative to the track rail. As illustrated on
the right
hand side of Figure 5, the connector 150 may be advanced onto the flange until
the
spring tabs 92, 94 engage the outside edge of the flange 42. These spring tabs
then
limit the advancement of the connector toward the track rail to help correctly
position
the clamp. As above, such spring tabs 92, 94 may be formed during a die
stamping
and bending process.
Though discussed primarily in respect to clamps having opposing outwardly
(e.g., laterally) extending teeth, it will be appreciated that variations
exist. For
instance, Figure 7 illustrates a clamp 200 that utilizes three teeth 56 on the
upper and
lower members to provide a secure connection to the track rail 40. As shown, a
first
set of opposing teeth are disposed on each member and a central tooth is
formed
through the middle of the upper and/or lower body of this U-shaped member 58.
Figure 8 illustrates a clamp 250 where individual gripping arms 260 include
opposing
teeth 262. In this arrangement the U-shaped member includes four opposing
gripping
arms 260 that each includes two teeth 262. Figure 8 also illustrates a clamp
after
stamping and prior to being bent into a U-shape. In any of these embodiments,
the
clamp may utilize integrally formed teeth that have a base section that are
integrally
formed with the elastically deformable U-shaped body.
Referring again to Figs. 2-8, each spring clamp may additionally include an
attachment portion 70 that may serve to structurally and/or electrically
(conductively)
connect a component to the spring clamp and ultimately to the track rail 40.
The
attachment portion 70 may include a tang 72 that extends from one of the
opposing
members. This tang 72 can be formed separately from the mounting portion 58
and
then appropriately attached thereto (e.g. via welding) or may be integrally
formed
with the clamp. Regardless of how the upstanding tang 72 is formed or shaped,
it
serves to as a location to mount the signal line 16 or other object to the
clamp.
In one embodiment, the signal line is removably attached to the spring clamp.
In this embodiment, a fastener extends through an aperture in the upstanding
tang 72.
See e.g., Fig. 7. The fastener 78 may be in the form of a bolt, screw and the
like, and
can include a threaded portion 80 and an aperture 82. The fastener 78 can be
inserted
or otherwise positioned through an aperture in the upstanding tang 70 before
or after
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CA 02737344 2011-04-14
the clamp is applied to the rail. An exposed core of the signal line can be
inserted
through the aperture 82 and a nut can be threaded onto the threaded portion 80
of the
fastener 78. At this point, the signal line 16 is in secure structural and
electrical
contact with the spring clamp. As such, once the clamp is appropriately
mounted to a
portion of the track rail 40, the signal line 16 will be electrically
connected to the
track rail. To remove the signal line 16 from the spring clamp 50, a user may
loosen
the nut and pull a portion of the fastener 78 through the bore such that
exposed core
18 is not compressed against the front surface 74. At this point, the signal
line 16 can
be removed. In other embodiments, the signal line 16 can be permanently
attached to
the signal line connector 100. For instance, a signal line or cable may be
welded,
brazed, adhered (e.g., using a conductive epoxy) or otherwise connected to the
upstanding tang 72.
To prevent against rusting or oxidation, the various components of the signal
line connector 100 can be appropriately coated or otherwise conditioned. For
instance, the spring clamp and/or the connection between the spring clamp and
a
signal line can be hot-dip galvanized (e.g., with a layer of zinc) to inhibit
corrosion
therebetween. In other embodiments, the connection between the spring clamp
and
the signal line can be electroplated (e.g., nickel) or dip coated in a layer
of
thermoplastic. Further other materials or substances may be applied in any
appropriate manner to prevent contact with air and/or moisture.
In order to provide a desired clearance between the signal line 16 and the
surface of the track rail 40, the physical configuration of any or all of the
components
of the various spring clamps may be altered. For instance, the height of the
upstanding tang 72 may be increased. That is, by increasing the height of the
upstanding tang 72, additional clearance may be provided between the U-shaped
body
and the top surface of the flange 42 of the track rail 40. Alternatively or
additionally,
the length of the opposing members can be altered to correspondingly change
the
clearance between the signal line 16 and a neck portion of the track rail 40.
Fig. 9 illustrates use of the spring clamp 50 of Figs. 4A-4D to support a
component relative to the track rail. That is, rather than making an
electrical
connection with the track rail, the clamp is utilized to attach a
component/element
relative to the rail. In this particular embodiment, the clamp supports a
track rail
heater assembly relative to the track rail 40. That heater assembly includes a
hood
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CA 02737344 2011-04-14
member 220 that extends along a portion of the length of the track rail and
provides
an at least partially enclosed interior that houses an electrical heater 222.
Generally,
the hood member 220 is an elongated member the length of which may be chosen
to
accommodate the length of a particular heater. In addition, end plates (not
shown)
may be provided to substantially cover the ends of the hood member. This may
reduce convective heat loss to the ambient environment. In the present
embodiment,
an upper portion of the hood member 220 is adapted to engage the head flange
of the
track rail 40 and a lower portion of the hood member is adapted to engage a
web
portion of the track rail 40. That is, a first contact surface contacts the
head flange
and a second contact surface contacts the web. Accordingly, this may require
that the
hood member be suspended above the foot of track rail. In the present
embodiment,
the hood member includes a lower connecting link 224 that is bolted to an
upstanding
tang 70, which provides a connection point for the clamp. It will be
appreciated that
in this embodiment, two or more clamps may be disposed along the length of the
heater assembly.
Figures 10A and 10B illustrate another embodiment of the spring clamp 50.
However, in this embodiment, rather than having an attachment portion
interconnected to the upper member 54, an attachment portion 110 is
interconnected
to the lower member 52. This lower attachment portion allows for interfacing
the
spring clamp 50 with a tie 120 underlying the track rail 40. In the present
embodiment, the attachment portion 110 includes an aperture 112 that allows
for a
bolt, spike or other fastener to pass through the attachment portion and into
the tie
120. However, this is not a requirement. In such an arrangement, the spring
clamp
may be utilized to maintain the positional relationship of the rail 40 to the
underlying
tie 120. As will be appreciated, in many railroad applications, significant
vibratory
forces are applied to the rail and underlying ties by trains passing over the
tracks.
This is especially evident in high-speed railroad applications. In such
arrangements, it
is not uncommon for the ties to migrate relative to the overlying rail.
However, use of
the spring clamp with an attachment portion adapted for interfacing with a
railroad tie
may allow for maintaining the positional relationship of these elements.
Specifically, it has been determined that the use of the laterally extending
teeth
56 on the top and/or bottom members 52, 54 of the spring clamp provides
significant
resistance to the lateral movement of the clamp relative to the flange of the
track rail.
CA 02737344 2011-04-14
Such resistance to lateral movement is illustrated in Figs. 11A and 11B.
Figure 11A
shows a top view of a spring clamp 50 connected to the flange 42 of a track
rail 40.
Figure 11B illustrates a cross-section along the reference line B-B'. As
shown, once
the clamp 50 is applied to the flange 42, the gripping tips of the laterally
extending
teeth 56 penetrate into the surface of the flange 42. The penetration of these
teeth 56
into the surface of the flange 42 is limited by the bottom and top surfaces of
the upper
and lower members 52, 54, respectively. That is, the angle of bend between the
teeth
and the generally planar surface of the upper and lower members dictates a
maximum
depth that the teeth may bite into the surface of the track rail 40.
To further improve the lateral stability of the clamp, at least one of the top
or
bottom member 52, 54 includes first and second opposing lateral teeth that
extend in
opposite directions at a common axial location (e.g., relative to centerline
axis C-C').
For instance, the upper member 54 may include first and second opposing teeth
56a,
56b which extend laterally outward from first and second lateral edges of the
clamp
50. As shown, these opposing teeth may extend outwardly from a common location
along (e.g., axial location) the length of the upper and/or lower members. In
this
regard, any sideways force applied to the clamp is resisted (e.g., cancelled
out) by
these aligned teeth. Furthermore, by utilizing four teeth on the upper and/or
lower
members (e.g., two sets of opposing teeth), the clamp 50 is also very
resistant to
rotational movement about an axis normal to the clamp. This resistance to
rotational
and/or lateral movement along the length of the flange 42 thereby provides a
mechanism that allows for maintaining the positional relationship of the rail
to the
underlying tie. For
instance, a clamp having a downwardly extending
member/attachment portion 110 may be located on the rail on opposing sides of
the
tie. Though illustrated as being connectable to the underlying tie, it will be
further
appreciated that the attachment portion 110 interconnected to the lower member
52 of
the clamp 50 may not be mechanically attached to the tie. Rather, the
attachment
mechanism may simply be located proximate to the side surface of the tie to
prevent
the tie from moving relative to the track rail. Furthermore, these downwardly
extending members/attachment portions may be spaced from the tie to prevent
some
relative movement between the tie and the rail to account for, for example,
thermal
expansion of the track rail. However, in such an arrangement, the movement of
the
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CA 02737344 2013-08-26
track rail relative to the tie may be maintained between two adjacent clamps
interconnected to the flange of the rail.
17
