6. Switch expansion joints (SEJ) are provided at the ends of long
welded rails to allow for the cumulative thermal expansion
movements of the ends of the rails
10. The "track bed" is the layers of ballast and
sub-ballast above a prepared
subgrade/formation (see diagram). It is
designed primarily to reduce the stress on
the subgrade.
The trackbed can significantly influence the
performance of the track, especially ride
quality of passenger service
11. GAUGE
The perpendicular distance between the inner
faces of heads of the two rails forming the track is
known as the ‘Gauge’.
Broad Gauge - 1676 MM
Meter Gauge - 1000 MM
Narrow Gauge - 762 MM OR 610
MM
Broad gauge is known as Indian standard gauge.
The WORLD standard gauge is 1483MM.
12. RAILS
Rails are continuous girders which carry the axle
load.
Functions:-Provides
Hard and smooth surface for the wheels of a train
to roll on
Bears lateral stress and vertical loads due to
breaking and thermal stresses.
Transmit load to the formation through sleepers
and ballast.
13. Types of Rails-
Double headed rails
Bull headed rails &
Flat footed rail or Vignoles rails(Invented by
CHARLETS VIGNOLES)
95% of the railway track in the world laid with this form
of rails.
Classification According to Size:
1.60KG Rails
2.52KG Rails
3.90R
16. Manufacture of Rails:-
Most commonly used alloy steels are:
1.Medium manganese steel
2.High Manganese steel
3.Chromium Steel
Standard Lengths of Rails are:
12.8 M for B.G
11.89 M for M.G
17. SLEEPERS:
Sleepers are transverse ties in a Railway Track
Functions:
To support the rails firmly and evenly
To maintain gauge correctly
To transfer the load from rails to ballast
To maintain alignment of the track
18. Types of Sleepers:
1. Timber or Wooden sleepers
2. Steel Sleepers
3. Cast Iron Sleepers
4. R.C.C Sleepers
Classification according to the size:
60 Kg 2.74 m x 25 cm x 13 cm on
BG
52 Kg
19. BALLAST
Broken stone or any other suitable material
placed below and around the sleepers.
Functions: Provides
1. Provides Hard and level bed for the sleepers to
rest on
2. Provides to hold sleepers in position
3. Provides Elasticity to the track
4. To drain away the rain water and prevent its
percolation into the formation
20. FORMATION
Distribute the load of traffic from the sleepers to
the formation without
Progressive settlement
Permit drainage of the track
Prevent lateral movement of the track
Prevent longitudinal movement of the track, and
Afford a convenient medium for packing the track
to cross level and
21. Rail fastenings:
Fish Plates and Fish Bolts
Spikes and hook Bolts
Chairs and keys
Bearing Plates
Functions:
Distribute the load coming on rails to the sleepers
over a large area.
To hold Rails to the sleepers firmly