Fittings for Wooden Sleepers
Rails are fixed to wooden
sleepers with the help of simple types of fastenings such as spikes, screws,
and bearing plates.
1 Dog Spikes
This
fastening is named dog spike (Fig. 10.5) because the head of this spike looks
like the ear of a dog. Dog spikes are used for fixing rails to wooden sleepers.
The number of dog spikes normally used is as follows:
Location Number of dog spikes
l On
straight track 2 (1 on either side and duly staggered)
l On curved track 3 (2 outside and 1 inside)
l Joint sleepers, bridges 4 (2
outside and 2 inside)
The dog
spike has a 16-mm square section and its length varies depending upon the
location at which it is placed, as given in Table 10.4.
Table 10.4 Details of dog spikes
2 Round Spikes
Round
spikes (Fig. 10.5) are used along with anticreep bearing plates for fixing
rails to sleepers. These are also used for fixing assemblies of switches onto
wooden sleepers. The round spike has a round section of a diameter of 18 mm,
and its length depends upon the purpose it serves. Round spikes have become
obsolete now.
3 Fang Bolts
Fang
bolts (Fig. 10.5) are employed under the switches for fastening slide chairs to
the sleepers. These are used in locations where the gauge is to be preserved.
4 Screw Spikes
Indian Railways has developed
screw spikes with diameters of 20 mm and 22 mm (Fig. 10.6) to be used on
high-speed, main, and trunk routes in order to increase the lifespan of wooden
sleepers. Screw spikes with a diameter of 20 mm are called 'plate screws' and
are used in place of round spikes for fixing rails to sleepers with the help of
anticreep bearing plates while screw spikes with a diameter of 22 mm are called
'rail screws' and are used to directly fasten the rails to the sleepers with or
without the use of bearing plates. They are also used on bridges and platform
lines. Plate and rail screws should be preferred to round and dog spikes in
order to conserve the life of wooden sleepers.
5
Bearing Plates
Bearing
plates are used for fixing wooden sleepers to rails. The different types of
bearing plates in use on Indian Railways are described below.
Mild
steel canted bearing plates Mild steel canted bearing plates
are used on all joints and curves to provide a better bearing area to
the rails. They have a cant of 1 in 20 and a groove in the centre to prevent
rocking. Mild steel (MS) canted bearing plates with only round holes are
sanctioned for use on the Railways. The normal size of this kind of bearing
plate is 260 mm × 220 mm × 18 mm for 52 kg and 90 R rails (Fig. 10.7).
Flat MS
bearing plates Flat MS bearing plates are used at points and
crossings in the lead portion of a turnout. No cant is provided in these
bearing plates. The size of this bearing plate is 260 mm × 220 mm × 19 mm for
52 kg and 90 R rails (Fig. 10.8).
Cast iron
anticreep bearing plates Cast iron (CI) anticreep bearing plates are
provided with wooden sleepers at locations where the rails are likely to
develop creep. These bearing plates have a cant of 1 in 20 and can be fixed
using normal round spikes. The size of this bearing plate is 285 mm × 205 mm
for BG tracks (Fig. 10.9).
Special
CI bearing plates for BH rails Special cast iron bearing plates
are used for fixing bull headed (BH) rails. The rail is held in position
with the help of a spring key (Fig. 10.10).
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