RailFanning is a gift you give yourself. - Varun

Trivia :- Black and Coalfield were originally ER and HWH based coaches maintained by HWH! When Coalfield and more specifically Black (the older of the two trains was introduced) Dhanbad didn't have a CCU!
Later when CCU came up in DHN, Coalfield was alloted to have PM in DHN! (Note :- Shantiniketan didn't exist then, Agnibeena was known as Bidhan named after 'Dr Bidhan Chandra Ray' (the founder of Durgapur)then and had a shorter rake then , used a different rake) and Black was shifted to at HWH!
Unfortunately ER lost DHN...
more...

to ECR even after a tremendous resistance from the now Honourable Bengal CM!
The tides were reversed and Coalfield was alloted to ER/HWH who put Coalfield in an RSA pattern with 12341/42 and 12337/38 post 2007!
Black was alloted to DHN/ECR inspite of their constrasting schedules :P
So HWH & DHN came up with an 'handshake' arrangements with each other!
Both Black and Coalfield share their primary maintainence at HWH & DHN respectively.
22387/88 has main overnight primary maintainence at HWH. It spends lesser time at DHN than it does at HWH! PM at HWH ; Secondary PM at DHN
12337/39/41 twin train combo is taken care by both DHN & HWH combo...
12341 comes from ASN makes a go and return trip as 12337/38 and returns as 12339....PM at DHN
12339 returns to HWH.......Secondary PM at HWH....returns as 12342....
ASN plays no role in maintainence and the rake as Agnibeena lies on ASN platform overnight!