CE's Circular No: - 208

 

                             Sub :  Laying of PRC Fanshaped Turnouts

                   

          With no new procurement of wooden and steel turnout sleepers all Division will have to undertake renewal of existing wooden and steel turnouts with PSC Fanshaped turnouts in big way. All track Engineers should therefore make themselves familiar with intricity of Fanshaped layout and should know and ensure correct fittings and components required and should ensure same has been correctly fixed. Following details are enumerated to ensure correct laying of Fanshaped Turnout.

 

1.1      Left Hand and Right Hand turnouts:

1.1.1       It should be appreciated that Left Hand and Right Hand turnouts of same angle and rail section are true mirror images of each other in case of wooden sleepers, holes have to be drilled and in case of steel sleepers, holes exit for providing loose jaws. Steel sleepers when rotated 180° horizontally become mirror image of the previous dis-position and therefore, the same sleeper can be used for left hand as well as right hand. In both these sleepers, therefore, no problems are to be faced in using them both on Left Hand as well as Right Hand turnouts.

 

1.1.2       Ordinary concrete sleeper turnouts: - Difficulty is, however, faced in using the same concrete sleeper for both Left Hand and Right Hand turnouts as the contact between insert and rail is a line contact along the insert face. Once the sleeper is rotated by 180° the insert face inclination does not match the inclination of rail at that location because the inserts have specific length. It, therefore, becomes necessary that Left hand and Right Hand turnout sleepers are designed separately in case of concrete sleepers. This will involve doubling the inventory and creating a lot of confusion at the time of use.

 

1.1.3       Fanshaped layouts: - To overcome the aforesaid problem and with a view to use the same sleeper both for Left Hand as well as Right Hand turnouts, Fanshaped design of turnouts has been developed. The salient aspect in this design are: -

 

i)                    The sleepers under switch portion are having dowels in which slide chairs are fixed with the help of rail screws. These sleepers are laid perpendicular to the main line and therefore, can be used both for Left hand and Right Hand turnouts.

 

ii)                   The sleepers between the switch and crossing (lead portion) are laid at an angle of Q/2 with respect to main line where Q is the angle between the main line and the lead rail at the particular location. The same sleeper of Left Hand turnout can be used for Right Hand turnout by laterally shifting the sleepers rotating the same by an angle of Q.

 

iii)                  The sleepers under crossing are laid perpendicular to the centre line of the crossing and as such the same sleeper can be used for both Left hand and Right Hand by lateral shifting.

 

iv)                For laying sleepers in the lead portion correctly, spacing of sleepers on left rail seat and right rail seat (on main straight track) are given which define the centre line of the sleepers.

v)                 To illustrate the disposition of sleepers for Left Hand and Right Hand layout, please refer to figures in Annexure-I.

 

2.                  Before laying the turnouts, the correctness of the switch as well as its curvature should be checked in advance by pre-assembling and then once again after laying in track. The curvature should be checked at location given in Annexure-III & IV and should be recorded beforehand.

 

3.                  PRC sleeper turnouts should only be laid on stable formation. This layout needs efficient drainage and adequate ballast cushion. It is, therefore, necessary that deep screening is done and full ballast cushion of 30 cms is provided before such turnouts are laid. It should be noted that due to close spacing it is very difficult to deep screen manually after laying of PRC layouts.

 

4.                  It should be noted that the sleepers are the same for 52Kg and 60Kg rails.

 

5.                  A mark 'RE' is provided on Fanshape PRC turnout sleepers at one end. The sleepers should be laid in a manner that this end having the mark 'RE' is always laid on the right hand side.

 

6.                  The dowels fixed in the PRC sleepers should be cleaned with the help of a suitable round soft brush so that all dirt / muck is removed from them, making the fixing of the screw easy.

 

7.                  All the screws required to be fixed in the dowels should be greased before being put in.

 

8.                  For the guidance of the field staff and to serve as ready reckoner complete details of various parts and fittings as indicated below are enclosed herewith as various Annexures: -

 

Annexure-I

Illustration of Para 1.3 (Disposition of lead sleepers)

Annexure-II

RDSO drawing Nos. of various assemblies and disposition of sleepers.

Annexure-III

A general plan indicating sleeper spacing, curvature of sets and details of machine/welded joints, etc. for 1 in 12 layouts.

Annexure-IV

A general plan indicating sleeper spacing, curvature of sets and details of machine/welded joints, etc. for 1 in 8½ layouts.

Annexure-V

A to B

Details of fittings for 1 in 12, 60Kg. Fanshape turnout indicating sleeperwise fittings and other details.

Annexure-VI

A to B

Details of fittings for 1 in 12, 52Kg. Fanshape turnout indicating sleeperwise fittings and other details.

Annexure-VII

A to B

Details of fittings for 1 in 8½, 60Kg. Fanshape turnout indicating sleeperwise fittings and other details.

Annexure-VIII

A to B

Details of fittings for 1 in 8½, 52Kg. Fanshape turnout indicating sleeperwise fittings and other details.

 

 

 

 

 (C.K.Narasimhan)

 CHIEF TRACK ENGINEER

 

 

 

Annexure-II

 

FANSHAPE LAYOUTS

 

 

RDSO Drg. No. of Main Assembly

 

 

 

A 1 in 12 turnouts

 

Main Drg. of T/O

Switch Sub-assembly

Crossing Sub-Assembly

60 Kg.

 

52 Kg.

RDSO/T-4218

 

RDSO/T-4732

RDSO/T-4219

 

RDSO/T-4733

RDSO/T-4220

 

RDSO/T-4734

 

A 1 in 8½ turnouts

 

Main Drg. of T/O

Switch Sub-assembly

Crossing Sub-Assembly

60 Kg.

 

52 Kg.

RDSO/T-4865

 

RDSO/T-4865

RDSO/T-2 6(Alt.1)

 

RDSO/T-4866

RDSO/T-4967

 

RDSO/T-4867

 

 

   DISPOSITION OF SLEEPERS

 

Type of Layout

Sleeper under switch which are to be laid perpendicular to the main line.

Sleeper Nos. which are to be laid at angle Q/2 where Q is inclination if outer lead rail with respect to main line at that location.

Sleeper No. to be laid perpendicular to centre line of crossing

1 in 12

 

1 in 8½

1 to 20

 

1 to 13

21 to 64

 

14 to 41

65 to 83

 

42 to 54