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Anil Kumar Shahi
ADEN UMR,SEC Rly

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PostPosted: Wed Aug 20, 2008 2:51 pm Back to top

Life of rail is well defined in terms of ,GMT Passed ,Wear,Corrossin.condition basis, But Life of glued Joint & CMS Crossing iis not defined in terms of GMT ,only wear is the replacement criteria for CMS crossing.
1. Now I just want to know what should be the Life of CMS crossing in terms of GMT passed?
In New Tender schedule of procurement of weldable CMS crrossing service Life is told as 200 GMT for without reconditioning or 260+ _ GMT for awarding excess/less payment if crossing tolerates Max. traffic after passage of Traffic more than 260 GMT? may 200 GMT taken as service life of GMT for ordinary CMS crossing? Is there any guareenteed service life for ordy CMS crossing.?
2. Life of Glued joint is spelled max.7 years , but I want to know the criteria for fixing 7 years as the service life.What will be service life of glued joint in terms of GMT like defined for rails?
stipulated Life of welding joint in IR and also in advance country is half of the stipulated life of rail for 60 KG comes 400 GMT.But life of glued joint depends upon life cycle of various materials like Epoxy,Gloss cloth,End post,side channels.HTS botlts.Fish plates.so life of glued joint should be taken=400 GMT or >400GMT(i.e.minimum life of the fabricating material whichever is less.
2ns thing can we enhance the life of existing glued joint by repairing end post ,
in some of advanced railway glued joint is being repired for inhancing life by removalof burr on gauge face and filling of material
Burr formation in glued joint

(i)1st step is grooving

(ii) 2nd step is filling/Inserting of glued/adhesive

(iii)3rd step is grinding the rail top by using a hand held rail profile grinder

by using this technique they became able to enhance life of glued joint

Memberes are requested to comment please.

Anil Kumar Shahi
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PostPosted: Mon Oct 20, 2008 8:01 pm Back to top

Recently an extensive survey is organized in one of section containing 2000 glued joint and after plotting the data on various criteria I arrived on the following conclusion
1. Glued joint life is directly proportional to GMT passed over it, It comes about 200 to 250 GMT.
2. 85% of glued joint failure occured due to fishplate fracture
3.10% failures occured due to separation of glued & insulation.
4.Rest all failure occured due to Bolt snapping and other reasons.
In other country also during various study Life of glued joint experienced as 200 GMT Passage.
after modification of Fishplate design and increasing the nos of HTS fishbolts life of glued joint is increased up to 400 GMT and more.

MANOJ ARORA
CHIEF ENGINEER (CONSTRUCTION)

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PostPosted: Tue Oct 21, 2008 12:57 pm Back to top

At glued joint the transmission of longitudinal forces are ensured by provision of 6 HTS bolts provided with adequate torque. (I believe there is no need to futher increase number of bolts) But at the rail top there is a discontinuity experienced by wheel, while passing over central post insulation. As this post gets depressed and it is not able to support wheel at rail level. This discontinuity of 10 mm causes lot of hammering and over stressing of fish plate and HTS bolts. (Normally fracture initiates in fish plate from first bolt hole at the receiving end.). Because of this hammering the joint between the sleepers becomes visibly low causing further increase in hammering and loose packing under the sleepers on both sides of glued joints.

It has been an experience that if the spacing of sleepers across glued joint if reduced to 49 cm (i.e. sleeper centre at the centre of 1st and 2nd bolt on both side of central post), hammering and the tendency of glued joint of becoming low is drastically reduced. It helps in reduction of mechanical fracture of fish plate/fish bolt & failure of insulation. Spacing of 49 cm will still facilitate machine packing with certain precautions. This has been tried in Bhusaval division with great success.
            
            
            
- MANOJ ARORA PROFESSOR WORKS ... 21-10-08

Anil Kumar Shahi
ADEN UMR,SEC Rly

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PostPosted: Sat Oct 25, 2008 8:12 pm Back to top

In plain track by closing the sleeper spacing will definitely prove helpful to control the premature failure. But most of the population of glued joint are put in points and crossing zone where due to Fixed spacing of 610 MM , closing of sleeper spacing is not possible.Under the fish plated part ordy. elastic ERC can not be used and End cut GFN liner with J clip is being used which is having lesser Toe load so, easily worked out very ofetnly.
            
            
            
- Anil Kumar Shahi  ... 25-10-08

V. B. Sood
Director (B & S)

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PostPosted: Sat Oct 25, 2008 8:38 pm Back to top

Proper spacing of sleepers, periodic packing of the sleepers, and ensuring that the fittings, liners and rubber pads are maintained properly will go a long way in increasing the life of the glued joints.
            
            
            
- Vivek Bhushan Sood Professor/Bridges ... 25-10-08

MANOJ ARORA
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PostPosted: Mon Oct 27, 2008 11:41 am Back to top

In order to increase Toe load we may resort to provision of double rubber pads with J clip. Alternatively we can also try Old Clip ( i.e. mark III) by grinding it towards fish plate side by 3 mm. Probably it will give more toe load than J clip.
            
            
            
- MANOJ ARORA PROFESSOR WORKS ... 27-10-08
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