SSDSpring Setting Devices

Increasing the radius in turnouts (to minimise jerks and enhance passenger comfort) requires longer switch lengths. However, rails are not rigid in the longitudinal direction and hence do not provide required clearance even after reasonable opening at toe.

Rahee’s SSD solves this problem by ensuring housing of the closed tongue rail while maintaining adequate minimum opening of open tongue rail for wheel passage. During the change of setting, the point machine/alternate drive arrangement moves the tongue rail at toe. This, in turn, closes the spring till half its movement; then, for the other half of the tongue movement, the spring thrusts the housed tongue rail against the stock rail to have complete housing. Meanwhile the open tongue rail on the other side opens up adequately for passage of wheel. This is suitable for moderately long switches.


  1. Increases service life of tongue rail
  2. Ensures no reverse bend in tongue rail
  3. Works as a second drive for switches
  4. Eases installation process without affecting traffic
  5. In case of spring failure, tie bar remains connected to tongue rails ensuring safe traffic movement