Dragline excavators, known simply as draglines, are large excavating machines used for surface mining and terrain development. Draglines operate by lowering a bucket onto the terrain from a boom and then reeling the bucket in with a winch located in front of the machine. A blade on the bucket scrapes and collects surface material until the bucket is full, where it is then raised and emptied into a dump truck or designated location.
Draglines used for the construction of roads, ports, or other infrastructure projects are typically smaller than draglines used for mining, and can be disassembled and relocated. These types of draglines are typically mounted on caterpillar treads, and many cranes can be implemented as draglines. Most of these draglines are diesel-powered.
Draglines meant for the removal of overburden above coal or for tar-sand mining are amongst the largest vehicles ever constructed. These machines are purpose-built and rarely leave the excavation site. Draglines of this magnitude are mobilized by 'walking feet' which pick-up and replace the dragline a couple yards at a time; caterpillar tracks would sink or collapse in loose soil below the machine. Furthermore, mining draglines are often hardwired into a high-voltage grid due to its immense power requirements.
Despite the sizeable cost of draglines, they remain popular due to their reliability and ease of waste removal.