Thursday, March 29, 2018

Maintenance of SWR

Regular maintenance operation –

(1) Regular track maintenance including all operations involving packing, lifting,
aligning, local adjustment of curves, screening of ballast other thandeep screening, and scattered renewal of sleepers may be carried out without restriction when the rail temperature is below tm. +25o C in the case of zone I & II and tm + 20o C in the zone III and IV. However on curves of less than 875 metres radius Broad Gauge,and less than 600 meters radius in Metre Gauge or yielding formation, the above temperature limit shall be restricted to tm. +15oC in the case of Zone I and II and tm. + 10oC in the case of Zone III and IV.

(2) If the maintenance operations have to be undertaken at temperature higher than that mentioned above , not more than 30 sleeper spaces in one continuous stretch shall be opened, leaving at least 30 fully boxed sleeper spacer between adjacent lengths which are opened out. Before the end of the days work it shall be ensured that the ballast is boxed up.

(3) As an additional precaution, during summer months, to be specified by the Chief Engineer, for attention to run down track, even if temperature is less the temperature specified not more than 30 sleepers in one continuous stretch shall be opened, leaving at least 30 boxed sleeper spaces between adjacent lengths which are opened up.
Further, if joint gaps are not available at the time of opening of the track even when rail temperature are less than those specified not more than 30 sleepers in one continuous stretch should be opened leaving at least 30 boxed sleeper spaces
between adjacent lengths which are opened up.

(4) Major lifting, major alignment of track, deep screening and renewal of sleepers in continuous length. - Each of these operations shall be done under suitable precautions and normally when the rail temperature is below tm. +150C in the case of Zones I and II, and tm. +100C in the case of Zones III and IV. If it becomes necessary to undertake such works at rail temperature exceeding the above values adequate speed restrictions shall be imposed.

(5) Adequate number of joggled fish-plates with special clamps shall be provided to the gangs for use in emergencies.

(6) In the case of any fracture in the weld or in the rail, the portion of rail with fracture is cut, and removed for a length of not less than 4 M. to carry out the rewelding duly introducing a rail piece of equivalent length, also ensuring that no
weld lies closer than 4M. from the fish-plated joint.

(7) Conversion of 10 rail/5 rail panels into shorter panels – It will be desirable to
convert the existing 10 rail panels and 5 rail panels into 2-1/2 rail panels wherever maintenance problems cannot be solved otherwise. Wherever conditions permit, conversion of SWR into LWR may also be considered.

Gap Survey and Its Adjustments

Gap survey and adjustment of gap –

(1) General - Gap survey and rectification of gaps is to be carried out, in stretches where track develops excessive creep jammed joints, sun kinks, buckling, wide gaps, battered and hogged joints, fractures at joints and bending of bolts etc. In SWR the gap survey and adjustment should normally be done before the end of February once a year (i.e., before onset of Summer).

(2) Gap Survey –

(a) The gap survey shall be conducted on a clear and sunny day in the cool hours of the day.

(b) The length over which gap survey is to be done should, whenever possible, be divided into suitable sub-sections, each bounded by fixed points such as level crossings, points and crossings etc.The survey should be completed during as short a time as possible, by employing adequate number of parties so that the rail
temperature is not likely to vary appreciably.

(c) The joint gaps shall be measured by taper gauge in mm. (shown below) and the readings entered in the pro forma as shown in Figure

(3) Recommended range of value of gaps – The recommended range of value of
gaps (in mm.) during service for various ranges of rail temperature is indicated in
the table given below :–

Note –( I ) The gaps given above are to be distinguished from the values given in
Para 503 ( Table – I ) which are intended to be provided at the time of initial laying of SWR.

( ii ) Gap survey should be carried out when rail temperature is in rising trend only.

(4) Calculations for adjustment – The average of the measured gaps are worked out as shown in the pro forma for gap survey (Annexure 5/2). A comparison of the results of the gap measurements recorded and the permissible values of gap 

Case 1 – Average gap is within the recommended range, but some of the individual gaps fall outside the range.
Case 2 – Average gap falls outside the recommended range.
Case 3 – Average gap as well individual gaps fall within the range.

(5) Action to be taken – The action to be taken is as follows :–

Case 1 – Rectification work should be restricted to correcting the individual gaps, which falls outside the recommended range. Rectification should be done by pulling the minimum number of rails. Under no circumstances shall the adjustment be done by cutting a rail or introducing a longer rail. 
Case 2 – The joint gaps shall be systematically adjusted from one end to the other end of the subsection. The rails shall be unfastened over convenient lengths, the gaps adjusted to the initial laying gaps as per Para 508 and rails fastened. In this case introduction of a longer or shorter rail will be involved. Efforts should be made to see that only the minimum numbers of joint sleepers are disturbed.
Case 3 – No action is to be taken. As far as possible, the day chosen for rectification should be a day on which the rail temperature is not likely to vary much during rectification period.

Conversion of SWR into LWR –

The following additional precautions should be observed when converting SWR
into LWR:–

(1) The anticipated residual life shall be at least 10 years.
(2) The rails shall be tested ultrasonically and all defective rails replaced before conversion into LWR.
(3) Rail ends which are hogged or battered or have a history of cracks in bolt hole region, shall be cropped before conversion into LWR.

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