patri ke is taraf ya us taraf, zindagi mein hum sab RailFan ek taraf - Ananya D'Souza

The subclass ‘C’ signifies that this loco is equipped with conventional brake rigging system.
The G9 locomotives have an arrangement called TBU (Tread Braking Unit) to apply the loco brakes.
This is a somewhat heavy unit which can apply individual brake on any wheel. Probably the original intention was to enable selective braking on any axle to provide better adhesion through wheel slip control. However, in reality, the TBU system has been an issue since long like that of vibration of TBUs and TBUs getting dislodged/dislocated.
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be more specific when brakes are applied using effective cylinder pressure, then brake shoe try to stop the wheels. Now with this conventional brake rigging system, after application of brakes, the axle set and wheel dismantling will not happen. Also, the magnitude of Braking Force can be obtained from the DDU (Driver Display Unit) with this system in place.
Thus, this WAG-9 HC is Heavier Load with Conventional Brake Rigging. The conventional brake rigging is cheaper and easier to maintain, weighs less and is mostly trouble free in operation.
From now on, probably all new WAG9s will belong to the HC class.
I got this info from IRI ..