Note: Descriptions are shown in the official language in which they were submitted.
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This invention relates to a system oE securing
rails to wooden rail tiesO
Conventionally rails have been secured in place to
rail -ties by placing a metal plate between the rail tie and
the rail and securing the rail to the tie by driviny dog
spikes into the tie such that the dog spikes pass through the
metal plate and a flange on the spike lies over the rail
flange. Usually four spikes are used (two on either side of
the rail) for each sleeper and the metal plate incorporates
slots in predetermined positions for this purpose. The
difficulty encountered with these conventional wooden rail
ties are: (1) Due to wood shrinkage the dog spikes gain
clearance above the rail flange leading to a loosening of the
rail; (2) Due to the constant passing of trains the rails
tend to distort resulting in a vertical hammering on the dog
spikes and again tending to loosen them; ~3) In curved
sections of the track the pressure of passing trains causes
the metal plates to cut into the wooden tie on one side of
the rail and this results in ~he metal plate becoming
inclined and distorting the horizontal support for the rail:
(4) Because of the constant traffic and the inadequate
holding force of the dog spikes the wooden ties tend to move
and drift apart or together and do not maintain a regular
spacing - once again resulting in inadequate rail support;
(5) Once a plate loosens it hammers vertically on to and
gradually cuts into the wooden tie.
Attempts to overcome these problems using elastic
rail fasteners such as "Pandrol" have proved ineffective.
With elastic fasteners the metal plate is modified to
incGrporate means for holding one portion of the fastener
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while a second portion lies on the rail flange. The metal
pla-te is still secured to the tie by dog spikes but the rail
is secured on to the metal plate by the elastic fasteners.
These systems have proved ineffective because the problems
(1) to (4) above still tend to occur mainly because the metal
plate still becomes loose and the fastening of the metal
plate to the wooden tie is still by dog spike and this
affects the functioning of the elastic fastener.
German Patent 1,253,297 and U.K. Patent 2,022,657
each provide a fastening system comprising a rail plate
positioned between a tie and a rail, an elastic rail clip and
a clip holding means having spikes adapted to pass through
holes in said rail plate to hold said rail plate in position
and secure said clip holding means to said rail tie. These
two specifications do provide a solution to the problems
outlined above~ However, the clip holding means in both
these specifications requires expensive manufacturing
techniques as each clip holder needs to be cast and then
further treated.
It is an object of the present invention to provide
a rail fastening system for wooden rail ties that minimizes
manufacturing costs.
To this end the present invention provides a rail
fastening system comprising a wooden rail tie, a rail, a rail
plate positioned betwePn said tie and said rail, a pair of
attachment means located on opposite sides of said rail,
adapted to secure said plate to said wooden tie, each said
attachment means incorporating a recess above said plate and
a spike extending in-to said tie and an elastic rail clamp
associated with each pair of attachment means said clamp
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being oE the kind ln which one portion lies on the rail
flange and the other portion is held within opposed recesses
of said pair of attachment means.
By using pairs of attachment means rail clips of
the kind shown in German Patent l,253,297 and U.K. Patent
2,022,657 can be secured in position wit~out using the rail
clipholders of those two specifications.
By using attachment means which function to secure
the plate and hold the elastic rail fastener the problems of
prior art systems are avoided. Any vertical movement of the
attachment means due to wood shrinkage or rail movement due
to traffic load is accommodated within the working deflection
range of the elastic fastener. Elastic fasteners are
designed to provide an adequate hold down force over a range
of deflection distances (that is thP vertical distance
between portion of fastener on the rail and the portion held
in the attachment means). However, in the prior art because
the plate i~self was effectively the holder for the fastener
when it became loose because of loosening of the dog spikes
from the wooden tie the effective hold down force between the
tie an1 the rail was lost. In this invention the attachment
means ensures that a direct link between the rail and the
rail tie is maintained.
Ideally each attachment means includes a spike
section for fastening to the wooden rail tie and a recessed
shoulder portion for accommodating portion of the fastener.
To further illustrate this inven-tion a preferred
embodiment will now be described with reference to the
drawings in which:
Figure l is a cross sectional view of a rail
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fastener of this invention in position;
Figure 2 is a perspective view of a rail seat; and
Figure 3 is a sectional view of an attachment means
of this invention.
In Figllres 1 and 2 the rail flange 5 of the rail 4
lies on the support plate 6 which in turn is seated on the
~ooden rail tie 7. The attachment means 10 extends into the
rail tie and secures the elastic fastener 15 in posi~ion.
The base 16 of the elastic fastener 15 seats within
the recess 11 of shoulders 12 of the two attachmen-t pegs 10
as shown in Figure 2. The arms 17 of fastener 15 lie on rail
flange 5.
Each attachment peg 10 includes a serrated spike
portion 13 which carries at its end an elastic barb 14. The
serrations and the barb 14 retain the spike securely within
the wooden tie 7. Left and right hand attachment pegs 10 are
used with each rail fastener 15 and these pegs pass through
preformed slots 9 in the support plate 6.
When correctly positioned the elastic fastener 15
can be deflected within the range of 8 to 17 mm and still
maintain a satisfactory hold down force and without
subjecting the fastener to undue stress. This deflection
range means that any shrinkage of the wooden rail tie or
vertical movement of the rail will be accommodated by the
fastener. The support plate still functions to spread the
load from the rail to the sleeper but plate movement no
longer affects the attachment of the rail to the rail tie.
Since the elastic fasteners can be removed without
affecting the positioning of the sleeper plate replacement of
rails is a simple matter whereas in the prior art the dog
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spikes holding the rail, must be removed. Once removed the
dog spikes of the plate must be repositioned on the tie.
Such re-insertion of the dog spikes can only occur a few
times before the tie suffers "spike kill". This problem is
avoided in the present invention and rails can be replaced
without affecting -the position of the support plate on the
tie.
Unlike the clip holders of U.K. Specification
2,022,657 and German Patent 1,253,297 the attachment pegs 10
are much cheaper to manufacture (1) because they require
less material and enable a saving in metal to be made; (2) if
they are cast in moulds because of their smaller volume a
larger number of pairs of legs can be made per moulding box
than either of the clip holders of the prior art patents
mentioned above: (3) the pegs 10 of this invention need not
be cast but can be forged from metal bar by forming and
stamping which represents a significantly cheaper means of
manufacturi~g because it avoids the energy and time consuming
procedures of casting and moulding.
Thus the system of this invention overcomes the
problems of the prior art in a simple way and still enables
the support plates used with conventional dog spikes to be
utilized.
