31. Over hauling of Alarm chain system is done after ----- Month. (a) 3 (b) 5 (c) 9 (d) None of these 32. Centre pivot of Casnub Bogie is made of ----- (a) Cast Iron (b) Cast steel (c) Mild Steel (d) Stainless Steel 33. Proof load Capacity of enhance screw coupling is -----ton.