Ballast Cleaning
INTRODUCTION
• Contamination of the ballast bed in the course of normal operation and due to the extremely varied environmental influences, plus the geological problems of the subsoil in total lead to a reduction in the durability of the permanent way.
• Ballast cleaning technology provides the prerequisites for economical maintenance of the track.
• In situ condition and engineering aspects of ballast are important conditions governing the stability and performance of railway track.
•In order to remain competitive with other mode of transportation, railway authorities have increased freight tonnage, traffic speed and frequency of train. These changes have led to increase wear from rails down to sub grade level. Hence effective design and proper ballast maintenance remain the best alternative.
•The dynamic effect of traffic causes breakdown of ballast particles accompanied by attrition of its grains. The fines thus generated decrease void volume and retain moisture. Due to decrease in permeability ballast loses its ability to drain the track consequently decreasing shear strength, stiffness and elasticity. Trapped water decreases the necessary interlocking,deteriotates track geometry, loosen fasteners. Hence ballast cleaning becomes essential.
Advantages
• Required slopes can be given to the formation.
• Quality of ballast cleaning extremely good.
• Loss of ballast negligible, upto 10-15%.
YOU MAY ALSO READ: The duty of TECH III, PRE BLOCK WORK, ABOUT BCM, Know CSM, TAMPING UNIT
Various operations
• Screen excavated material and immediately return back good ballast.• Grade track ballast to various sizes, distribute them as per requirement.
• Discharge spoil from front of machine to keep track free behind machine for re-ballasting.
• Can excavate all materials in ballast bed without screening, if required.
• Can provide sand blanketing between sub grade and ballast, if required.
Methods of Ballast Cleaning
1. Shoulder Ballast Cleaning
• Most cost effective way to remove sub-surface saturation problems.• It breaks open mud pockets and releases trapped water to restore drainage.
2. Mobile Apparatus Ballast Cleaning
•A train consisting a ballast cleaning machine with a track lifting mechanism is used.•The waste material is conveyed from ballast cleaning machines to freight cars through conveyor belt.
•It is a fast method of ballast cleaning.
3. Recent method
•Reconditioning of ballast is done at relatively high speed.•Track Undercutters and Ditcher wheels are used to remove ballast.
•This is followed by screening in which reusable ballast is recovered from removed portion.
•Typical Ditcher wheels can remove ballast upto 5000 feet in 1 hour.
•Articulated system which can negotiate on small radius curves to maintain overall height is used.
• A dust suppression system consisting of main pressure lines is used.
• Spraying of liquid is employed to minimize effect of dust particles.
YOU MAY ALSO READ: The duty of TECH III, PRE BLOCK WORK, ABOUT BCM, Know CSM, TAMPING UNIT
Ballast Cleaning Machines
1. High Output Ballast Cleaners ( HOBC )
• Proper utilization of HOBC is ensured by accurately predicting volume of ballast returned to track and new ballast needed for renewal.• Site investigation prior to renewal is done. For this either samples from trial pits( TP ) are used or automatic ballast sampling is done.
2. FRM 80
•It’s a six axled articulate machine.•First section consist of pick up device.
•Second section consist of screening unit, filling devices and conveyor belt.
•Entire ballast is picked up by cutters positioned on either sides.
•Picked up ballast is transported to cleaning units.
•Waste material falling out is dropped into hopper unit by spoil conveyor units.
•After cleaning sweeper unit restore the ballast profile.
Technical Data FRM 80
Total length, over buffers 39 470 mmTotal length (incl. Slewing conveyor belt) 41 970 mm
Length of excavation car 19 235 mm
Length of screening car 20 235 mm
Length of overhang of slewing
conveyor belt 2 500 mm
Height over top of rail max. 4 200 mm