Write a short note on Automatic Contrivance

 Engine for manwinding shaft more than 100m depth is required to be provided with automatic contrivance to prevent: Over speeding, Over winding, excessive landing speed of down going cage,cage runing in wrong direction after over winding.                                                         Automatic contrivance--(1)Prevents over speeding of cage:it sounds an alarm when normal speed is exceeded and if the speed is not reduced it initiates brake application.     (2)Warns the driver when to commence retardation and if the cage is not retarded,it applies brake.   (3)cuts off the power and applies brake if after an over wind the cage starts in the wrong direction. (4) prevent the down going cage from landing at a speed greater than 1.5m/s (it is called slow banking).                   In view of many accident in shaft,DGMS and the coal companies have decided to provide Automatic Contrivance in shafts of depth between 75and 100m also.(DGMS Cir.Tec. 1/1993).                                                     
Automatic contrivance is tested by a competent person: for over winding once in every 7days by raising the cages in turn above the landing,for slow banking once in 3months by attempting to land the descending cage at excessive speed.

Mining Engineering

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Mining Engineering

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