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ATDs are meant for regulation of tension in OHE conductors & one of the
important equipment, which need special attention in respect of installation as
well as maintenance, as improper installation & maintenance may lead to
disturbed OHE profile, resulting in poor dynamic behavior of OHE, which may on
occasion cause panto entanglements at turnouts/cross-overs, neutral section etc.
3.2 The failure pattern of last 7 years has been thoroughly studied by RDSO & it is
observed that most of the failures of SS wire rope are with winch type ATD.
Failures of 3 pulley ATDs have also been reported 2003-04 onwards, even
though it has contributed only 4% to failures, with population of 45 % on IR.
RDSO has reframed the maintenance instruction for 3-pulley type ATDs, clearly
indicating action to be taken during monthly & annual checks and POH of ATDs,
so as to arrest failures of stainless steel wire ropes and ATD.
3.3 Special attention needs to be given during POH as per laid down instructions,
because if POH is carried out properly, certain specified checks may not be
required to be carried out during other schedules and performance of ATD can
be improved to a large extent.
3.4 Railways having large number of failures, may like to complete the cycles of
visual checks, if possible, utilizing magnifying glass without taking power block.
It will help to identify the ropes with broken strands, as in certain cases,
Railways have been reporting strands cutting on counter weight side.
DETAILS OF SPECIAL MAINTENANCE INSTRUCTIONS:
4.1 MONTHLY CHECKS
4.1.1 Check for missing Balance Weights and if found missing, panto lower/raise
caution or speed restriction for passing trains (in tension lengths involving turn
outs, crossovers and overlaps) should be imposed by the concerned staff.
4.1.2 Check for free movement of ATD by slightly pushing up or pulling down the
counter weights. If obstruction in movement of counterweights is observed and
the counterweight do not come back to the position from where pushed / pulled
measure the force required to move the counterweights with the help of spring
balance. If the force is more than 10 kg, then take the following action:
a) Check the parallelism of hex tie rod of antifalling device and if required,
set it right.
b) Check for bent/deformed/ missing guide tube and deformation of eye of
base counterweight and deformation of counterweight eye rod, take
corrective action to remove the defects. If the equipment is completely
jammed, the equipment should be dismantled and bearings should be
replaced with only SKF 6305 – 2RS1 or NBC 6305-LLU.
4.2 Annual Checks:
4.2.1 Auto Tensioning Device:
(i) Check visually whether all the pulleys are in same vertical plane, pulley block
of the ATD is in alignment with the OHE and the bent arms of the pulley
block are parallel to the pulley. If not, then check, center to center distance
of holes of the bent arms of pulley/pulley block. If the holes do not match
with each other, replace bent arms.
(ii) Check that eye & clevis is free to swivel, if not, file the back of clevis to
obtain sufficient clearance between it and the edge of the anchor fitting,
without seriously affecting the strength of the fitting.
(iii) Check the angle spacers over hex tie rod are free to move.
Page 3 of 10 Effective from 01.04.2006 Maintenance Instruction No..TI/MI/00029 (Rev-3)
SMI-0029, Rev-3
(iv)Check that the hex pipe of suitable length have been provided over hex tie
rods as per the table given in ANNEXURE-A.
4.2.2 STAINLESS STEEL WIRE ROPES:
(i) Check thoroughly the condition of stainless steel wire rope through
magnifying glass for loose wires/strands, broken wires/strands, rusting,
pitting/corrosion and bird caging. If any of these defects is observed, the
wire rope should be replaced immediately with new lubricated wire rope.
(ii) Lubricate the wire ropes at least once in a year with “BALMEROL ROPELUBE
1000”.
4.2.3 ATD & WIRE ROPE COMBINED
(i) Check that the stainless steel wire rope is centrally placed over the groove of the
pulleys, if not, then release the tension on ATD and manually set the wire ropes
centrally on the grooves.
(iii)Check for rusting / corrosion /deformation /breakage of all the
components. If these are observed, then the defective components should
be replaced.
(iii) Check for appreciable grazing of side walls of pulleys, by the wire rope . If
appreciable grazing of side walls of pulleys is observed, then take the
following action:
(a) Straighten the side walls of pulley by a few mild blows with wooden mallet.
If these can not be straightened, replace the pulley/pulleys.
(b) Loosen or tighten the bolt connecting the bent arms to the clevis & eye to
ensure that there is no grazing between & the section of wire rope carrying
counterweight.
© Check that the mast anchor fitting is correctly fitted so that its eye is in
horizontal plane. If not, fit it correctly, by loosening the bolts connecting it
to mast, set the anchor fitting right and tighten the bolts. If the
deformation/ manufacturing defects on the mast anchor fitting are
observed, it should be replaced.
(d) Check if the pulley is tilted in vertical plane towards the bent arm
right/left. If it is, then insert a beveled washer in between the clevis of eye & clevis and mast anchor fitting from bent arm right/left side, so that
pulley becomes vertical.
(iv)Check X-Y dimensions and if required, adjust them according to
adjustment charts as given in ANNEXURE-B.