Bogie Open Hopper Wagon Bottom Discharge --- Designed in year 1991 these are Open hopper car with rapid (pneumatic) bottom discharge doors, air-braked. Most often used for carrying coal to thermal power plants, and also for ore, stone, track ballast, etc. Each wagon holds some 56 tonnes of coal loaded from the top and unloaded from the bottom by means of the pneumatically operated doors. The contents of the wagon can be discharged completely in about 15 seconds. The door-opening mechanism is triggered by lineside devices running on a 24V or 32V DC source. As the wagons in a rake pass by the triggering devices, their doors open and their contents are unloaded into the pits below the tracks (the 'merry-go-round' system). These versions used in Indian railways have 8 bottom doors. The wagons are mounted on two cast steel Casnub 22 NLB Bogies with single pipe pneumatic air-brake system. Spring O-12 & I-8, S-4. Fitted with centre buffer coupler (CBC). Capacity - 55.68 Tonnes. Type - BOBRN.