When purchasing  the explosion-proof  crane for  coal mine,  the coal  mine enterprise preferably provide the cross section of the chamber and indicate the following information: the height  of the chamber wall, the height from the ground to the  top of the cave, the width of the hole, the radian of the hole, the height  and width of the lifting weights, and  the left and right limits of the  lifting weight and the height of the lifting weights to be lifted.