13. Sets Of Switches
Pair of stock rail.
Pair of tongue rail.
Pair of heel blocks.
Several slide chairs.
Two or more stretcher bars. Gauge tie
plate.
Check rails.
13
14. stock rail
They are the main rails of the track to
which the tongue rails are fit closely.
They are the outer rail in the turnout
14
15. tongue rail
Rails which lie between the 2 stock
rails
End portion of the tongue rail is called
toe and is connected by stretcher bar .
It is the moving part of the switch
which diverts the train from one track
to the other.
15
16. heel blocks
These are the blocks inserted
between the heel of the stock rail and
tongue rail
Used to provide clear gap for the
wheel flange.
16
17. slide plates
These are the special plates which are
provided for supporting and sliding the
tongue rails.
It is essential because it helps the
tongue rail to move toward and away
from stock rails and tongue rails are
able to slide.
17
18. stretcher bars
Used to connect the toe of the tongue
rails so that both
the tongues moves through the same
distance or gap
Generally 2 or 3 bars are used near
and behind the toe
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19. Check rails
They are the rails which are used
guide the outer wheel flange of the
train.
To ensure that the train does not
derail.
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21. SWITCHES -TOE
Undercut switch
In case the height of the stock and tongue rail is
same, it is desirable to cut out a portion of flange at
the foot of the stock rail so that toe of tongue rail is
accommodated under head of the stock rail.
The disadvantage of this type of switch is that it
becomes weak because flange portion is cut out.
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22. Overriding switch
In this type separate rail sections of stock rail and tongue rail
are adopted.
The stock rail of heavy section and tongue rail of light
section are used instead of cutting the flange rather than
weakening the stock rail as in case of undercut switch.
- The tongue rail rides over the flange of the stock rail.
22
23. Some imp. term related to
switches
Switch angle:- angle between the
gauge face of the stock rail and that of
the tongue rail at its closed position.
Flangeway clearance:- the distance
between the adjoining faces of the
running rail and the check rail at the
nose of the crossing.
Gauge max. value (mm) min. value(mm)
BG 48 44
MG 44 41
23
24. Heel divergence:- the distance
between the gauge faces of the stock
rail and tongue rail at the heel of the
switch.
Throw of the switches:- distance of
lateral movement of tongue rail at the
toe of switch to allow movement of
train.
Gauge max. (mm) min(mm)
BG 115 85
MG 100 89
24
25. DESIGN OF TONGUE
RAILS
It may be curve or straight.
Straight rail having advantage are
following
1.easily manufactured.
2.used for both right hand as
well
left hand turnout.
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28. CROSSING
A crossing or frog is a device introduced
at the point where two gauge faces cross
each other to permit the flanges of a
railway vehicle to pass from one track to
another.
To achieve this a gap is provided from
the throw to the nose of the crossing ,
over which the flanged wheel glides or
jumps.
The other wheel is guided with the help
of check rails to ensure that the flanged
wheel negotiates the gap properly n so it
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29. COMPONENTS
Two rails, point rail and splice rail
Two wing rails
A pair of check rails
29
30. COMPONENTS
Two rails, point rail and splice rail
Two wing rails
A pair of check rails
30
35. There are three kinds on the
basis of manufacturing purposes:
35
36. Less wear and tear.
Longer life
Free of Bolts
Less maintenance cost
36
37. ON THE BASIS OF:
ASSEMBLY OF CROSSING
1.Movable or Spring crossing
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38. 2.Ramped crossing
RAISED CHECK RAIL FOR OBTUSE
CROSSINGS:
In order to provide a guided pathway
in the throat portion of a 1 in 8.5 BG
obtuse diamond crossing, the check
rails are raised by welding a 25 mm
thick MS plate. This arrangement is
considered satisfactory for BG as well
as MG routes.
38
40. Inspection and maintenance
Condition of tongue rails and stock rails.
Condition of fittings of tongue and stock rails- Fitting should be tight, and
spherical washer must placed correctly.
Gauge and cross level at switch assembly-
Correctness checked at location:-The stock joint, Behind the toe of switch, mid switch for the straight track,
Heel of switch
Clearance between stock and tongue rails.
Gauge and cross level of crossing assembly.
Check rails
Cross levels on straight tracks and turnouts
Sleepers
Ballast and drainage
40
Maximum Minimum
BG 48mm 44mm
MG 44mm 41mm
