Note: Descriptions are shown in the official language in which they were submitted.
BACKGROUND OF THE INVENTION
(i) Field of the Invention
.
This invention relates to a rail anchoring system
comprising a resilient rail anchoring clip and associated
5 sleeper, which is suited to all classes of rail systems
subjected to low axle loads (up to about 15 tonnes), medium
axle loads (about 15 to 25 tonnes) and high axle loads
(greater than about 25 tonnes). The clip is adapted, in use,
to cooperate with the sleeper which has apertures formed
10 through the upper surface thereof where, in use, a rail is to
be positioned.
T
-- 3
(ii) Description of Prior Art
Conventional resilient rail clips are sprung into
position on either side of the foot of a rail by torsion or
bending effects with one part of the clip bearing hard against
5 the upper surface of the rail foot, another par-t of the clip
being attached to the sleeper and bearing upwardly, whilst the
final part of the clip bears down on the associated sleeper to
balance the forces generated with the clip.
The effect of the above forces is to induce
10 additional stress in the area of the sleeper, adjacent the
rail, which can lead to failure of the sleeper.
Some types of such known clips are those
manufactured by Pandrol Limited of Britain under the name of
Pandrol (tra~e mark); Portec (Aust.) Pty. Ltd. under the name
15 Sidewinder (trade mark); Omark (Australia) Limited under the
name "Trak-Lok" (trade mark); and by B.V. Schroefboutenfabriek
v.h. Everts en van der Weijden of ~olland under the name D.E.
Springclips.
All of the above known types of rail clips act to
20 hold the rail foot against the sleeper against lifting forces
and forces transverse of the rail direction, but in order to
restrain the rail clip from moving longitudinally of the rail
direction high toe loads (the loads applied on the upper
surface of the rail foot) are necessary.
Other types of rail clips, commonly called rail
anchors, are known and are formed in one piece to e~tend
beneath the rail foot and engage on, or about, the edges of
the rail foot, whilst bearing against the side faces of the
sleeper. Such rail anchors act to restrain the rail agains-t
T
7~
longitudinal movement, but additional hold-down clips or
spikes are required to restrain the rail against lifting
and transverse movements.
Steel sleepers also have a history of fatigue
failure at the housings that locate the rail and/or clip
and the rail seat areas.
OBJECT OF T~E INVENTION
It is therefore an object of the present invention
to overcome the disadvantages associated with known rail
clips and associated sleepers, particularly insofar as
fatigue performance of the sleepers and costs are
concerned.
SUMMARY OF THE INV~NTION
In accordance with an aspect of the invention
there is provided a rail and sleeper assembly comprising a
sleeper, a rail, and a rail anchoring clip for anchoring
said rail on said sleeper, said rail having a vertical
axis and a foot having an upper surface, said ~leeper
comprising a longitudinally extending member which is
substantially U-shaped in lateral cross-section with
downwardly disposed sides extending from a bearing surface
portion, said bearing surface portion having an upper face
and a lower face, said upper face including a pair of
longitudinally spaced apart stop means thereon for
restraining lateral movement of said rail on said sleeper,
a pair of apertures each positioned on said sleeper at a
position such that said stop means is between a respective
~,
.~.~P
76~
aperture and said rail, said aperture being proximate ~o
said stop means, said clip being of resilient material and
in substantially U-shape having a first leg and a second
leg joined by a bridging portion, said clip extending
through said aperture in the sleeper and having an end of
one leg abutting tightly against the upper surface of the
rail foot and having the end of the other leg abutting
tightly against the lower face of said bearing surface
portion to compressibiy anchor the rail on to the sleeper.
- 10 Preferably positions of contact of the first
portion with the rail, the second portion with the sleeper
and the third portion with a wall of the aperture in the
sleeper~ are spaced apar~ in a direction longitudinal of
the sleeper. In a preferred embodiment the position of
contact of the first portion is positioned clos~r to the
vertical axis of the rail relative to the position of
0ntaCt of the second portion, which in turn, is positioned
closer to the vertical axis of the rail relative to the
position of contact of the third portion. The clip may
also be provided with means to prevent on assembly, over-
drive of the clip on the rail and sleeper assembly.
In accordance with another aspect of the
invention there is provided a rail and sleeper assembly
comprising a pair of rails, a sleeper and at least one
rail anchoring clip associated with each rail arranged
to anchor the rails to the sleeper, each said rail having
a vertical axis and a foot having an upper surface, said
'.
,.~,
76~
~- 6 -
sleeper being a longitudinally extending member sub-
stantially U-shaped in lateral cross-section having down-
wardly disposed sides extending from a bearing surface
portion, said bearing surface portion having an upper face
and a lower face, said upper face having two longitudinally
spaced apart pairs of longitudinally spaced apart humps,
eac~. hump having an inner rail-facing wall and an outer
waLl, said inner walls of a respective pair of humps
restraining a respective rail foot agains~ movement
longitudinal of the sleeper, said two longitudinally
spa~ed apart pairs of longitudinally spaced apart humps
cooperating to hold said pair of rails in longitudinally
spaced apart relation, at least one aperture in said
sleeper associated with each of said rails, each said
aperture receivably engageable of a respective clip,
each aperture positioned longitudinally outwardly of a
respective inner rail-facing wall relative to the vertical
axis of said associated rail; said clips formed of sub-
stantially U-shaped strips of resilient material, each
clip defining a first leg and a second leg joined by a
bridging portion, each clip extending through a respective
aperture longitudinally of the sleeper and having a portion
of said first leg abutting tightly against the upper sur-
face of the foot of the associated rail and a portion of
said second leg of said clip abutting tightly against the
lower face of said bearing surface portion, said bridging
portion cooperatively engaging at least one edge of said
i; ,
1;Z1~76~
~- 6a -
respective aperture to prevent lateral displacement of
said clip relative to the sleeper, whereby each rail is
compressibly anchored onto the sleeper.
In accordance with another aspect of the
invention there is provided a rail anchoring clip and
sleeper assembly comprising a sleeper and a rail anchoring
clip arranged in use to anchor a rail, having a vertical
axis and a foot having an upper surface, to the sleeper,
laterally of the sleeper, wherein said sleeper is a longi-
tudinally extending member substantially U-shaped in
lateral cross-section having downwardly disposed sides
extending from a bearing surface portion, said bearing
surface portion having an upper face and a lower face,
said upper face having a pair of longitudinally spaced
apart upwardly pressed humps, each hump having an inner
rail-facing wall and an outer wall, said inner wall, in
use, locating the foot of the rail against movement in
a direction longitudinal of the sleeper; at least one
aperture receivably engageable of said clip in said
sleeper, said at least one aperture positioned longi-
tudinally outwardly of said inner rail-facing wall,
relative to the vertical axis of the rail, said clip
formed of a substantially U-shaped strip of resilient
material defining a first leg and a second leg joined
by a bridging portion, said clip, in use, extending
through said aperture longitudinally of the sleeper and
having a portion of said first leg abutting tightly
,~ ..
,. . . .
7~
- 6b -
against the upper surface of the rail foot on the side of
the rail foot, relative to said rail axis, adjacent said
clip engaging aperture, a portion of said second leg abut-
ting tightly against the lower face of said bearing surface
portion~ wh~reby the rail is compressibly anchored onto the
sleeper, and said bridging portion cooperatively engaging
said aperture to prevent lateral displacement of said clip
relative to the sleeper.
Throughout this specification and claims there is
reference to contact or engagement between portions of the
sleeper and the rail foot and the anchoring clip and the
rail foot. It is however understood that such references
also embrace a situation where a non-conductive insulator
is positioned between the sleeper and the rail and between
the anchoring clip and the rail foot.
SUMMARY OF THE DRAWINGS
The invention will now be described by way of
example only, with reference to the accompanying drawings,
in which:-
Fi~ure 1, is a perspective view of part of a rail
attached to part of a sleeper,
Figure 2, is a perspective view of a rail anchor-
ing clip,
Figure 3, is a cross-sectional view of the clip
and part of the upper section of a sleeper together with
an associated rail, and
~-r~
~,
. . . ,~ , .
~R~7~ 7 -
Figure ~, is a plan view of par-t of the sleeper
without the rail.
DE:TAILED DESCRIPTION
Referring to Figures 1 to 4 of the drawings, a rail
5 assembly comprises at least a pair of rails 14 mounted on
steel sleepers 19 by the use of spring steel anchoring clips
10. For clarity the figures show only one rail, sleeper and
clip. Each anchoring clip is formed to adopt a generally U-
shaped configuration comprising upper and lower legs 8 & 9 and
10 a bridging portion 7 as shown. For light loads the clip is
approximately 40 mm wide and 6 mm thick, for medium loads 40
mm by 9 mm, and for heavy loads 50 mm by 8 mm.
The upper leg 8 of the clip, adjacent its free end,
is bent at 11 to provide line contact 12 against the upper
15 surface of one side of the foot 13 of the rail 14. The
bridging portion of the clip is adapted to e~tend through an
aperture 15 formed in a raised portion or bulge 18 in the
sleeper 19 and provides a line contact 16 against the outer
side of the aperture remote from the rail 14.
The lower leg 9 of the clip, and adjacent its free
end, is bent at 24 to also provide a line contact 20 against
the unc7.erside of the upper wall of the sleeper and underlying
the rail foot 13.
In a preferred embodiment the line contact 12 of the
25 upper leg 8 of the clip is positioned further inwardly (i.e.
closer to the vertical axis) or said rail relative to the line
contact 20 of the lo~er leg 9, which in turn is positioned
further inwardly o~ saicl rail relative to the line contact 16
of the bridging portion 7.
T
~ 8 -
The geometry of the fastening system is such that
with the clip 10 installed in the rail-sleeper assembly,
removal of -the clip can only be attained by an outward
movement of the lower leg 9 in a direction limited by the size
5 and location of the aperture 15 in the raised portion of the
sleeper. Outward movement of the clip 10 within the physical
constraints OL the aperture walls, sleeper and rail is
prevented by the opposing forces at the positions of contact
12, 20 and 16.
When an applied force tends to pull the bridging
portion 7 out of the aperture 15 the geometry and location of
the clip generates increased opposing forces.
The lower leg ~ of the clip 10 is also undulated to
provide a stop portion 21 which abuts the inside of the raised
15 portion of the sleeper adjacent the edge of the rail foot to
limit the extent to which the anchoring clip can be driven
into position.
Movement of the rail and clip lateral to the sleeper
will be resisted by friction between the rail, sleeper and
20 clip together with the abutment of the edge of the brid~ing
- portion 7 of the clip against the end walls 15a of the
aperture 15 in the sleeper.
Torsional rotation of the clip in the horizontal
plane will be resisted by frictional forces at line contacts
25 12 and 20 together with reactive forces from line contact 16
and the contact of the portion 21 of the clip preventing
overdrive with the sleeper.
~ s shown with particular reference to ~igures 1, 3
and 4 the sleeper is of generally U-shaped cross section, the
30 sides 27 and 28 of which converge into a planar bearing
T
portion 29. A pair of raised portions or bulges 18 are
pressed into the bearing portion 29 at prede-termined in-tervals
so that the inner walls 30 of adjacent bulges 18 act as spaced
abutments for the adjacent edges 31 of the rail foot 13. Each
5 bulge 18 comprises an inner wall 30 and an outer wall 32, the
outer wall having formed therein the aperture 15. The
aperture 15 is of generally rectangular shape and only
sufficiently larger in dimensions than the cross-section of
the strip forming the clip 10 to allow convenient location of
10 the clip into its operating position. The corners of the
aperture 15 are preferably rounded to eliminate crac~
2~2~2~70~ ~7~e~ ~e ~o~e~ g ~g~ a~ ~s~ ~7~
~ortion 7 vf the clip 10 may he chamfere~ in order to better
ma~ch the shape of the clip 10 to that of the aperture 15.
The outwardly extending bul~es 18 of the sleeper
described above are designed to produce an improved (enlarged)
bearing area between the sides 31 of the rail foot and the
adjacent inner walls 30 of the bulge to reduce the contact
stresses in the sleeper. In the case of insulated steel
20 sleepers in which an electrically insulating pad is inserted
bet~.~een the rail foot and the sleeper it is particularly
important to reduce the contact stresses to improve the life
of the insulator.
Furthermore, recent analysis in the United States of
25 ~merica has shown that the propensity of the track to buckle
in a lateral direction is reduced by increasiny the torsional
resistance offered by the rail fastening system. In this
regard the outwardly extending bulges which form a direct
bearing between the rail and sleeper substantially increase
30 the torsional resistance.
T
` 7~ o
The -tigh-t engagement of -the clip about the edge of
the rail foot and sleeper combination clamps the rail foot 13,
and thus the rail 1~, to the sleeper, to restrain the rail
against liiting movements~ The width of the clip relative to
5 the length of the aperture 15 is such that the clip edges wil]
lie in relatively close pro~i~ity to the end walls l5a of the
aperture such that li-ttle, if anv, movement of the rail
relative to the sleeper, and longitudinally of the rail
direction, is possible.
In the above described embodiment it is envisaged
that line contacts will be formed between the clip and the
rail foot, sleeper and aperture. However, in practice the
bending of the strip to form the clip tends to produce a
slightly concave surface on the outer sides of the bends.
lS This has the effect of providing laterally spaced apart point
contacts at the side edges of the clip and in use these may
also slightly penetrate the adjacent surface of the rail or
sleeper to achieve more positive engagement than the mere
frictional engagement which occurs with line contacts.
-20 However it is understood that the e~pression "line contact" as
used herein e~braces the situation discussed above. It is
also understood that the co~ponents may be designed to provide
surface contact areas instead of the line contact referred to
above.
Although in the preferred embodiment the aperture 15
is positioned in the outer wall of the bulge 1~, it is
understood ~hat the aperture 15 could be formed further away
from the bulge and therefore rail foot in a position of low
stress of the sleeper.
T
7~
Although the clip of -the invention has been
described in relation to assemblies incorporating steel
sleepers, the cllp is also applicable for use in assemblies
incorporating sleepers of other materials, for example
5 concrete and timber, and in which apertures, communicating
with internal cavities, are formed.
Preferablv the clip is formed from either carbon
steel, alloy steel or heat treated steel, although in some
applications it may be formed from a plastics material.
The major advantages of the clips and the associated
sleeper information as described above, are:-
(i) Low cost clips: simple to manufacture.
(ii) Simple application: hammered or pressed
into position.
(iii) Simple sleeper design requiring simple tools
for manufacture thereby reducing
manufacturing cost. Heating of sleeper
during forming is not required with lighter
sleepers thereby providing further
reductions in manufacture costs.
(iv) Positive gauge restraint or location of the
rail on the sleeper.
(v) The perforations of the sleeper to form the
apertures are such as to ensure that the
sleeper has long fatigue life. This
improved fatigue life is gained by the
position and shape of the apertures and the
forming of the sleeper section about the
area of the rail seat. Good fatigue
characteristics allow thinner material -than
T
C~ 7~ 12 -
other systems in current use (e.g. lanced
Pandrol (T.M.) housing) and therefore a
cheaper sleeper.
(vi) Vandal proof: clip cannot be }snocked out
with a rock or hammer. A special tool, such
as a slide-hammer, would normally be
produced to enable ease of disengagement of
the clips when necessary.
(vii) Clip cannot be overdriven due to
inbuilt overdrive stop facility.
(viii) Has 'snap in action' which prevents clips
working out.
(ix) Can be adapted to insulated and non~
insulated track.
(x) Low Profile: Less interference to track
grooming and less chance of damage from
track maintenance machines, dragging
equipment or derailments.
(xi) Greater resistance to track buckling due to
higher torsional resistance due to the
direct bearing of the rail foot or rail pad
on the projections in the sleeper.
(xii) Improved resistance to longitudinal rail
movement (rail creep).
It is to be understood that the invention includes
any modifications that would be envisaged by a person skilled
in the art and which do not depart from the spirit of the
invention, and any such modifications are to be considered
within the scope of the invention.
T
~ 13 -
Such modifications include varying the size of the
loop a-t the rear of -the clip to vary the toe load on the rail
foot and -the stress distribution within the clip. Si.milar
variations may be in-troduced by varying the dimensions of the
5 clip.
T
