A crane is a machine that can lift and lower materials as well as move them horizontally. It usually has a hoist rope, wire ropes or chains, and sheaves. It is primarily used for lifting and transporting heavy objects to other locations. The device employs one or more simple machines to generate mechanical advantage and thus move loads beyond the normal capability of a human. Cranes are commonly used in transportation for freight loading and unloading, construction for material movement, and manufacturing for heavy equipment assembly.