ppt for rail fixtures and fastening ... what types of fixture and fastening material use in railway

Brackets for rails

Any device used to secure rails on chairs or base plates or directly to sleepers, brackets or other rail supports. The rail fastening keeps the rails fastened to the sleepers (transfer of forces), provides adequate slope of the rail foot (1:20, 1:40) in the transverse plane, prevents the rail from moving longitudinally, dampens the noise And vibrations from the rails.
General requirements for rail fasteners
Rail fasteners shall:
1. Hold the rails firmly on the rail seat.
2. limit the rotation of the rail around the outer edges of the foot of the rail.
3. minimise the longitudinal movement of the rails through creep and thermal forces.
4. Assist in the retention of the gauge.
5. Do not damage the rail.
Whenever possible, the rail fasteners must be self-tensioning or allow clamping of the fastening to a predetermined load.
When existing rail closures are not effective in minimising the longitudinal movement of the rails, it is permissible to mount rail anchors as a method to meet this requirement.