SLEEPERS

1
SLEEPERS

• Sleepers are members generally laid transverse to
  the rails on which the rails are supported and
  fixed to transfer the loads from the rails to the
  ballast and subgrade below

2
Functions

• To hold the rail in correct gauge
• To hold the rail in proper level
• Act as an elastic medium in between the ballast
  and rails to absorb the blows and vibrations on
  moving loads
• Longitudinal and lateral stability of track

3
Classification of sleepers

• Wooden sleepers
• Metal sleepers
• Steel sleepers
• Cast-iron sleepers
• Concrete sleepers
• Reinforced concrete sleepers
• Prestressed concrete sleepers

4
Wooden sleepers

• Wooden sleepers are regarded to be best as they
  almost all requirements of an ideal sleeper
• The life of timber depend upon the ability to
  resist wear, decay, attack by vermin (white ants)
  and quality of timber

5
Limitations

• It is easily available in all parts of India
• Fittings of wooden sleepers are few simple in
  design
• Suitable for all types of ballast
• Difficult to maintain the gauge (in case of
  wooden sleepers)
• Track is easily disturbed (alignment maintenance
  is difficult)

6

• Minimum service life(12-15 years) compared to
  other sleepers
• Maintenance cost is high
• Types of timber for sleepers
• Hard wood (Sal or teak)
• Soft wood (chir, deodar)

7
Treatment of wooden sleepers

• It has millions of minute cells. The cell contain
  juices, and removal of the juices and filling up
  the cells with preserving solution is known as
  treatment of sleeper
• Preserving solutions
• Creosote
• Salt solution
• Bichloride of mercury salt solution(HgCl2)

8
Methods of impregnating timber

• Full cell process
• Empty cell process
• Haskenizing process
• Composite Sleeper Index (C.S.I)
• C.S.I (S10H)/20
• S strength index (both green dry timber _at_ 12
  MC)
• Hhardness index (both green dry timber _at_ 12
  MC)

9
Min value of C.S.I prescribed on Indian railways

• Type of sleepers Min C.S.I
• Track sleeper 783
• Crossing sleeper 1352
• Bridge sleeper 1455

10
Metal sleepers

• Metal sleepers are either steel or cast iron.
  cast iron is in greater use than steel for
  sleepers (less prone to corrosion)

11
Cast-iron sleepers

• Extensively used in India on a small scale in
  south africa.
• Types
• Pot or bowl sleepers
• Plate sleepers
• Box sleepers
• C.S.T-9 sleeper
• Rail free duplex sleeper

12
Steel sleeper

• In India , thousands of kilometrage of track has
  being laid using steel sleepers
• It is a inverted channel with folded ends. The
  folded edges which form a bulb, resist the damage
  caused by packing of ballast.
• Types
• Key type
• Clip-bolt type
• The saddle type