Write a short note on Automatic Contrivance
E ngine 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). ...