Big Muskie - Design Specifications and Service

Design Specifications and Service

The Big Muskie was a model 4250-W Bucyrus-Erie dragline (the only one ever built). With a 220 cubic yards (170 m3) bucket, it was the largest single-bucket digging machine ever created and one of the world's largest mobile earth-moving machines alongside the Illinois-based Marion 6360 stripping shovel called The Captain and the German bucket wheel excavators of the Bagger 288 and Bagger 293 family. It cost $25 million in 1969, the equivalent of $158 million today adjusted for inflation. Its bucket could hold two Greyhound buses side by side. It took over 200,000 man hours to construct over a period of about two years.

Big Muskie was powered by electricity supplied at 13,800 volts via a trailing cable, which had its own transporter/coiling units to move it. The electricity powered the main drives, eighteen 1,000 horsepower (750 kW) and ten 625 horsepower (466 kW) DC electric motors. Some systems in Big Muskie were electro-hydraulic, but the main drives were all electric. While working, Big Muskie used the equivalent of the power for 27,500 homes, costing tens of thousands of dollars an hour just in power costs and necessitating special agreements with local Ohio power companies to accommodate the extra load. The machine had a crew of 5, and worked around the clock, with special emphasis on night work since the per kilowatt-hour rate was much cheaper.

Once it had stripped all the overburden in one area of the pit, it could move itself short distances (usually less than a mile) to another pre-prepared digging position using massive hydraulic walker feet, although due to its 13,500 ton weight it traveled very slowly (1.76 inches per second (4.5 cm/s), roughly 0.1 mph) and required a carefully graded travelway with a roadbed of heavy wooden beams to avoid sinking into the soil and tipping over or getting stuck.

During its 22 years of service, Big Muskie removed more than 608,000,000 cubic yards (465,000,000 m3) of overburden, twice the amount of earth moved during the construction of the Panama Canal, uncovering over 20,000,000 tonnes (22,000,000 short tons) of Ohio brown coal.