Seating counts if booking opens
SLEEPER COMPARTMENTS (SL)

Total sleeper coaches 9 × 80 seats = 720 seats

General...
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quota (GN) = 286 seats
Tatkal quota (TQ) = 124 seats
Premium tatkal quota (PT) = 123 seats
Lower berth quota (SS) = 63 seats
Handicapped quota (HP) = 4 seats
Ladies quota (LD) = 6 seats
Pooled quota (PQ) = 36 seats
RAC allocation (126) = 126 / 2 = 63 seats
Foreign tourist quota (FT) = 2 seats
Defence quota (DF) = 2 seats

Total seats = 673 seats

720 - 673 seats = 47 seats for HO , EQ or any other quota

i am a frequent traveller in 12637 Pandian Express (TBM -->MDU)
when the train used to have ICF coaches ., the compartments would be so neat that you can say it with a big pride that Pandian Express is the most neat Train
off late , after changing to LHB coaches ., the cleanliness is lost ( 12637 ie towards Madurai)
during the...
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first few days . , rakes were not shared at all ., then with Rockfort Express (ok that how it was with ICF coaches even) and then for maximum utilization of the available LHB coaches
it was also shared with Cholan
now if you look at the RSA in indiarailinfo .com , you will know that 12637 starts with a minimal time interval after cholan arrives at MS (TPJ-MS)
to the officials concerned .,
please make sure the compartments are cleaned before the train starts from Egmore
during the rainy days , it is worst
one should think twice before entering a bathroom
Pandian on its return ie as 12638 looks pretty much neat compared to that of 12637
Travelers find it difficult while they are on 12637
sometimes i badly miss those neat ICF coaches
kindly do the needful