On our trip east every summer we pass through Estevan, Saskatchewan, where we often see the huge electric shovels at work mining coal. We took a few pictures of one monster 'walking drag line', and then decided to do some research to see how big these things can actually be.
It was then we discovered the legend of Big Muskie ... the largest moving machine ever built by man!
Be prepared to be astounded ....
Large shovels are often used to mine coal, which lies in thin layers near the surface. The top layers of dirt (called the 'overburden') are temporarily removed, the coal is excavated, and then the dirt is put back. This process is called 'strip mining', because it is done in huge strips along the land.
In this aerial view of the process, you can see a huge excavator at work. Although it looks like a shovel, this machine is actually called a 'walking drag line', because it moves by alternately lifting and lowering two gigantic 'feet', and the bucket is dragged byles instead of being anchored on the end of a steel arm.
Here you can see the seam of coal being mined; it's a thin layer below and behind the excavator, on the left. Smaller equipment in the centre-foreground is used to remove the coal.
This is the walking drag line excavator we saw while passing through Estevan, Saskatchewan. There are several coal mines nearby that are actively working, and several of these huge excavators.
Occasionally they have to be moved across the highway, which requires the construction of an earth roadway so that the pavement isn't destroyed. These drag lines are powered by electric motors, so they also have a huge powerle.
A 'walking drag line' is an excavator where the bucket is dragged byles, rather than lifted by an arm. This allows the bucket to be much larger than those on shovels. Drag lines, because of their enormous size, can't move with wheels or bulldozer tracks; they move forwards using hydraulically operated 'feet', which raise and lower, one at a time. That's why they're called 'walking' drag lines.
Below is a large photo of the mining operation at Bienfait, near Estevan. Notice the size of the other vehicles, even the earthmovers at the bottom of the pit, in comparison to the walking drag line.
An old dragline bucket. Emily is standing inside; she's just over 5 feet 10 inches tall. This is one big bucket!
Notice the teeth along the bottom edge; they're attached with bolts so that they can be replaced if they break or wear out.
Here is a comparison, side by side, of a drag line and a shovel. Bucyrus-Erie is the American company which makes many of these machines. These pictures don't show the relative size of each; the shovel is actually much smaller. Drag lines can be a whole lot larger simply because the boom and arm of a shovel can't be supported if they get too large.
The walking drag line on the left above is the Bucyrus model 2570WS, which has a bucket capacity of up to 120 cubic metres (160 cubic yards), and a boom length of 120 metres (400 feet). It can scoop up a single load weighing up to 360,000 kg, or 360 tonnes (400 tons). The machine itself weighs 7,200,000 kg (16,000,000 lbs).
The shovel on the right has a 122,000 kg (122 tonne) bucket payload, only a third as big, but still respectable!
Our research described many drag lines and large shovels built in the USA during the latter part of the 20th century, and the whereabouts of many of them are kept track of by people who are fascinated by these huge machines.
Many of these pieces of equipment are given names, and people come from all across the country to watch it work and to take photographs; when an old one is no longer in use, support groups form to help raise money for its preservation.
One of the largest and most famous American-built shovels was the enormous Silver Spade, seen here crossing a highway. Its size (although not its payload) rivals that of some drag lines. The Spade first went into operation in November 1965; the machine is now in service in Ohio. The Harrison Coal & Reclamation Park has plans to move their museum to the Spade when it shuts down, and make it part of their exhibit.
Specifications:
Height: 67 m (220 ft) Boom Length: 61 m (200 ft)
Bucket capacity: 79 cubic m (105 cubic yards)
Bucket load: 145 tonne (160 tons)
Machine weight: 6,400 tonnes (14,000,000 lbs)
The Silver Spade, like all shovels, moves itself around on crawlers like a tank or bulldozer, except that the crawlers are much larger. The Spade has three double sets on each side, each one being 34 feet long and 8 feet high; individual pads on the tracks weigh about 2 tons each.
Here are some photos of the Silver Spade in operation ...
The Big Muskie was a model 4250-W Bucyrus-Erie dragline, the only one of this model ever built. With a 220 cubic yard bucket, at 22 stories high she was the largest single-bucket digging machine ever created.
Here are some of her specifications:
Weight:
12 million kilograms (12,000 tonnes)
27 million lbs. (13,500 tons)
Bucket Capacity:
165 cubic m (220 cubic yards)
295 tonnes (325 tons)
Height: 68 m (222 ft)
Length of the boom: 95 m (310 feet)
Total length with boom: 149 m (488 ft)
Width: 46 m (152 ft)
Empty bucket weight: 209 tonnes (230 tons)
Powerle diameter: 12.7 cm (5 in)
Electrically powered: 13,800 volts
Big Muskie moved, as do most large mobile drag lines, on two huge hydraulically driven walking feet.
Big Muskie's bucket (pictured at the right) was large enough to hold 12 automobiles. The entire machine weighed more than 150 Boeing 727 jetliners, and the dragline used more electrical power than a city of 100,000 people.This excavator could dig a trench 56 m (185 ft) deep; in her working lifetime, Big Muskie removed over 608,000,000 cubic yards of overburden (twice the earth moved during the construction of the Panama Canal), uncovering 20,000,000 tons of clean coal. She cost a mere $25 million to build in 1969.
The gigantic boom drag chain.
The massive winches inside the.
On May 20, 1999, American Electric Power's Central Ohio Coal Company announced that the 220 cubic yard bucket of the company's historic Big Muskie dragline would be preserved as a historic monument to the men and women who worked the mines of southeastern Ohio. The bucket will become the centerpiece of a display that will tell visitors about the Big Muskie, surface mining, and reclamation in the area. Demolition of Big Muskie is currently underway, following the removal of the massive boom in 1999.
... and then there was 'The Captain' ...
Deas Plant, a visitor to our page, has pointed out that, while Big Muskie was incredibly large, it actually wasn't the largest!
He tells us:
"My information has Big Muskie at 14,200 tons. There was a Marion 6360 stripping shovel (similar to the Silver Spade), called 'The Captain' which burnt out some years ago due to a fire in its hydraulic system. This little toy weighed in at 14,800 tons."
Following a link provided by Deas, we found some incredible pictures of the Captain provided by Tim T., which show this 22 storey monster at work, and close-up.
The existence of Big Brutus, the second largest electric shovel in the world, was made known to us by visitor Allan Bowles. Now located at West Mineral, Kansas, Brutus is a Bucyrus Erie model 1850B.
Brutus is 16 stories tall (49 metres), and weighs 5 million kilograms. It has a boom that 46 metres feet long and that will hold 70 cu. metres (136 tonnes - enough to fill three railroad cars.)
See some large pictures of Big Brutus.
Click on the thumbnails at the right.
