Description :-  A derrick crane is a lifting device usually composed of mast (frame or tower) and lifting arm. There are three or four lines connecting the mast to the lifting arm, which controls it goes up and down. To lift a load, a separate line runs under the lifting arm with a hook as the hoisting mechanism. 

Function of Derrick Crane :-An oil derrick is used to dig a hole for an oil well, then to push the drill pipe deep into the earth. A mud mixture is sprayed from the drill bit to push material from the cuttings up out of the hole and cool the drill equipment, as well as to keep the bore hole stable.