Wednesday, March 28, 2018

MAINTENANCE OF TRACK-Through packing

Through Packing: Conventional Maintenance By Beater Packing:–

General: Operations in sequence:- O M S A G P R B

Through packing shall consist of the following operations in sequence. The length of track opened out on any one day shall not be more than that can be
efficiently tackled before the end of the day:
  • Opening of the road.
  • Examination of rails, sleepers and fastenings.
  • Squaring of sleepers. Slewing of track to correct alignment.
  • Gauging. Packing of sleepers.
  • Repacking of joint sleepers. Boxing of ballast section and tidying.
  • Through packing is best done continuously from one end of a gang length toward
  • the other.
 Each of the above operations should be carried out as detailed below :–

(a) Opening of Road:
Ballast should be opened out on either side of the rail seats to the extent shown hereunder to a depth of 50 mm. below the packing surface without disturbing the
cores under the sleepers:

(i) Broad Gauge : End of sleepers to 450mm. inside of the rail seat.
(ii) Metre Gauge : End of sleepers to 350mm. inside of the rail seat.
(iii) Narrow Gauge (762mm.) : End of sleepers to 250mm. inside of the rail seat.

In case of cast iron plate or pot sleepers, the opening out should be to the extent of the plates or pots to enable packing being done conveniently. The ballast should be drawn by powers/ shovels outwards and inwards i.e., that portion of the ballast on the outside of the rail should be drawn outwards, the portions between the rails being drawn towards the centre, care however, should be taken to see that the ridge between the rails does not project more than 50mm. above rail level.

(b) Examination of Rails, Sleepers and Fastenings –

1. Rails should be examined, the underside for corrosion, the ends for cracks, the
head for top and side wear, rail joints for wear on the fishing planes, fish bolts for tightness. If rails on curves wear at an unusually rapid rate, lubrication of the gauge face should be done. Rust and dust must be removed from the corroded rails by using wire brushes; kinks in rails should be removed by jimcrowing.

2. Sleepers should be inspected for their condition and soundness particularly at the rail seats. In case of wooden sleepers, plate screws, spikes and fang-bolts should be examined for their firm grip. Sleepers should be checked for split and decay. In case of cast iron sleepers, the condition and firmness of cotters and keys should be examined. Loose keys should be tightened by providing liners or replaced by appropriate oversized keys. In the case of wear in the rail seat of CST. 9 plates, suitable pad/saddle plates may be provided. Fastenings And fittings should be examined to ensure that they are in good order, appropriately tightened so that they firmly hold the rails. Broken ones should be replaced immediately.

(c) Squaring of sleepers:–

Gauge variations and kinks inevitably result from sleepers getting out of square.

1. The spacing of sleepers on the sighting rail should first be checked and correctly chalk marked. Corresponding marks should then be made on the other rail using the square at every point. The core of sleepers that are out-of square should then be ‘picked’ with the pick ends of beaters, the fastenings loosened and the sleepers levered and squared to correct position.

2. Squaring should be done by planting the crow bars firmly against the sleeper and pushing it. Under no circumstances should sleepers be hammered. Sleepers that are squared should be regauged immediately, the fastenings tightened and repacked.

(d) Slewing of track to correct alignment: -

1. Heavy slewing will only be required during realignment of curves when it will
be necessary to loosen the rail, joints and in case of steel sleepers and cast iron sleepers to loosen the fastenings, the packing cores being broken with the pickends of beaters. Slewing for normal maintenance will be of a small order and
should be done after opening out the road, loosening the cores at ends and drawing out sufficient ballast at the ends of the sleepers.

2. Slewing of track shall be directed by the Mate who on straights should sight the rail from a distance of 30 to 60 meters. On curves, he should sight the outer rail. Slewing is best done in the morning unless it is cloudy, as later on, sighting conditions become unfavorable. When slewing, the crow bars should be planted well into the ballast at an angle not more than 30 degrees from the vertical; otherwise lifting of the track may result.

(e) Gauging :–

1. Preservation of gauge is an important part of track maintenance especially through points and crossings. For good riding, the basic requirement is uniform gauge over a continuous stretch of track and such gauge should be allowed to continue so long as it is within the permissible limits of tightness or slackness.

2. Gauging should only be done after ensuring that sleepers are truly square. Standard keying hammers shall always be used. Beaters and heavier hammers should not be used, as this causes overdriving of keys and strained lugs on metal sleepers.

3. The track gauge should be held firm with one lug against the base rail, and the other end being swivelled over the opposite rails. The tightest position obtained determines the correct point to test the gauge. The gauge should not be forced as that causes considerable wear on the gauge lug.

4. The track gauge should be adjusted to correct gauge on the rail opposite to the base rail. The required slackness on sharp curves should be attained by usingliners of the requisite thickness against the lug of the gauge in the case of ordinary track iron gauge.

5. While it is desirable to maintain correct gauge, where due to age and condition
of the sleepers, it is not possible to maintain correct gauge, it is good practice to work within the following tolerances of gauge, provided generally uniform gauge can be maintained over long lengths:

Note: - These tolerances are with respect to nominal gauge 1676

(f) Packing of sleepers

1. The aim of packing is to have each sleeper firmly and uniformly packed to ensure that the rails are at their correct relative levels i.e., level on the straight track and to the required cant on curves and that no sleeper has any void between it and its bed.

2. Before packing is commenced, it is necessary to ensure that the chairs/bearing
plates are firmy fixed to the sleepers and the rails are bearing on the chairs/ bearing plates. In case of rails resting directly on sleepers it should be ensured that there is no gap between the bottom of the rail and top of the sleeper.

3. The base rail shall be sighted by the Mate with eye along the lower edge of the
head of rail and any dip or low joint lifted correctly. The adjacent sleepers should
then be packed and the top checked. After two rail lengths have been attended to,
the rail on the other side should be brought to the correct level by checking cross
level with the straight edge and spirit level or gauge-cum level at every rail joint
and at every fourth sleeper. The next two rail lengths should then be taken up and
the process continued.

4. No joint or dip should be lifted higher than the proper level in the expectation that it will settle to the correct level. Instead it will settle more under traffic as a result of being high and cause rough running.

5. Having aligned the track and adjusted the ‘top’ the Gang men should be distributed in batches of two for packing all sleepers in a systematic manner, commencing from one end. Four men should deal with every sleeper successively, two at each rail seat. The ballast under the sleeper should be packed
by the men standing back-to-back and working their beaters diagonally under the
rail seat at the same time to ensure firm packing.

6. It is important that men should thoroughly ‘break’ the cores with the pick-ends
and then use the blunt-ends (head-ones), as otherwise, uniform packing will not be achieved and elasticity of the roadbed affected. After packing the rail seat the packing should be continued outwards and inwards to the requisite extent on each side of the rail seat i.e., end of the sleeper to 450 mm. inside on the B.G. and end of sleeper to 350 mm. inside on the M.G. and end of sleepers to 250 mm. inside on the N.G. (762 mm.). The beaters should not be lifted above the chest level, thestrokes being kept as nearly horizontal as possible. Care must be taken to avoid forcing the sleeper any stones so large as to cause uneven bearing and to
avoid striking the edges of the sleepers and timbers. All men should aim to work
the beater from the same height (chest level) so that the sleepers are uniformly packed. Higher or lower lifting of the beaters results in uneven compactness.

7. In case of steel trough and wooden sleepers, packing under the rail seat causes the ballast to work towards the center. Before final dressing is done, it should be
ensured that no sleeper is centre-bound by working the pick-ends over the central
range. Centre bound sleepers cause vehicles to roll from side to side.

8. In the case of CST. 9 sleepers it should be ensured that the end pockets or bowls are filled with ballast and the main packing should be done at corners. The central flat portion of the plate should not be packed hard but only tamped lightly. On pots leepers the ballast should be punned through the holes provided at the top of the pot and rammed in with crow-bars.

9. Care must also be taken while packing to ensure that the work does not result in the sleepers adjoining those being packed, lifted off their bed, thus creating artificial voids under them.

10. The packing on the inside and outside at every rail seat should, before boxing the track, be checked by the Mate by tapping with a wooden mallet or a canne-a boule. A hollow sound would indicate defective packing which should be attended to again.

11. As soon as the packing is completed, slight distortions in alignment and top should be checked and corrected by the Mate, the sleeper disturbed for this purpose being finally repacked.

(g) Repacking of joint sleepers:

The joint and ‘shoulder’ sleepers should be repacked, before boxing is done and the cross-levels at joints checked. The rail joint being the weakest portion, firmness of its support is essential.

(h) Boxing to Ballast section and Tidying –

1. After completing the preceding operations in sequence, clean ballast should be
worked in with ballast forks or rakes. The ballast section should be dressed to the
specified dimensions, a template being used for the purpose. Hemp cords 6 mm. dia. of sufficient length should be used for lining the top and bottom edges of the
ballast section. Where the quantity of ballast is inadequate, full section of ballast
should be provided near the rail seat, the deficiency being reflected along the centre of the track and not under the rails or in the shoulders.

2. The cess should then be tidied up. Where earth ridging is existing at the edge of the bank, this should be removed. Cess should be maintained to the correct depth below rail level according to the ballast-section and formation profile. Too high access affects drainage; too low a cess results in ballast spread and wastage.

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