Indian Railways has purchased over 430 tie tamping machines during the last few years, which have been giving satisfactory results. These machines have been found most suitable for wooden and concrete sleepers and the condition of the sleepers maintained using these tie tampers is definitely superior to those maintained by the conventional method of beater packing. Indian Railways is systematically introducing long welded rails and concrete sleepers on high-speed routes and the
tie tamping machine is ideally suited for the maintenance of such tracks. However, the following points require special consideration for the successful implementation of mechanical methods of maintenance on Indian Railways.
Blocks Adequate time blocks of about 3 to 4 hours/day should be made available so as to make mechanized maintenance effective and economical.
Ballast cushion A clean ballast cushion of a depth of about 20 cm (8") should be available below the sleeper bed of each track that is to be maintained mechanically.
Repair facilities Adequate facilities for repair and overhauling should be made available at the site and in the workshop.
Spare parts A good stock of spares should be kept ready at hand to ensure that the machines are always in good working order.
Training of staff The staff employed for working the tie tamping machine should have thorough knowledge of the principles and method involved in its working. A full-fledged training school equipped with the necessary models and equipment should be made available to train the staff hired for the mechanical maintenance of tracks.
20.4.1 Tier System of Track Maintenance
With the introduction of concrete sleepers and on-track tamping machines on Indian Railways, three-tier system of track maintenance is being adopted on all sections nominated for mechanized maintenance. This system consists of the following three tiers of track maintenance.
(a) On-track machines units (OMU)
(b) Mobile maintenance units (MMU)
(c) Sectional gang
Tier 1: On-track machines unit
The work of systematic mechanized maintenance of track is done with help of heavy on-track machines, which include tie tamping machines for plain tracks as well as points and crossings, shoulder ballast cleaning machines, ballast cleaning machines, ballast regulating machines, and dynamic track stabilizers. These machines are used when the following tasks are to be performed.
(a) Systematic tamping of plain track as well as of points and crossings
(b) Intermediate tamping of plain tracks as well as of points and crossings
(c) Shoulder ballast cleaning, ballast profiling/redistribution, track stabilization, periodical deep screening
Tier 2: Mobile maintenance units
Picking up of slacks and other related works are done with the help of mobile maintenance units (MMU). The Railways use two kinds of MMUs whose functions are as listed below.
MMU-1 (Rail-cum-road vehicle based) One such unit is provided to each PWI in charge of a 40-50 km long double line or a 90-100 km long single line with a view to carrying out the following work.
(a) Need-based spot tamping
(b) Casual renewal and repairs, except planned renewals; in situ rail welding
(c) Overhauling of level crossings
(d) Replacement of glued joints as well as rail cutting or drilling and chamfering
(e) Permanent repair of fractures
(f) Creep or gap adjustments involving the use of machines; destressing of LWR/ CWR
(g) Loading/unloading of materials and other miscellaneous functions
MMU-II (Road vehicle based) One such unit should be kept aside for each subdivision. It is used for the reconditioning of turnouts and for the minor repairs of the various equipment that are a part of the MMUs. A list of all the equipment included in the two MMUs is given below.
Components of MMU-I Spot tamping machines such as track tampers and lifting jacks, rail cutting and drilling equipment, rail welding equipment, destressing equipment for rail tension, etc., gas cutting equipment, material handling equipment, safety and protection equipment, inspection gadgets and communication equipment.
Components of MMU-II Reconditioning equipment for points and crossings such as the welding generator, arc welding equipment, hand-held rail grinder, equipment such as spanner and gadgets for minor repairs.
Tier 3: Sectional gangs
Under the three-tier system of track maintenance the section gangs are required to perform the following functions.
(a) Patrolling of the track, namely, the keyman’s daily patrol, hot/cold weather patrolling, monsoon patrolling, patrolling of vulnerable locations
(b) Dealing with emergencies by carrying out temporary repairs as in the case of fractures
(c) Giving need-based attention to bridges, turnouts, SEJs, and approaches to level crossings
(d) Greasing of ERCs, lubrication ofjoints, casual changing of rubber pads and other fittings
(e) Minor cess repairs, cleaning of drains, and boxing of ballast
(f) Paying attention to loops
(g) Creep and gap adjustment not involving the use of machines
(h) Cleaning of crib ballast for effective cross drainage
(i) Pre- and post-tamping attention
(j) Assistance in the working of MMU and OMU as required