Marion 5760 The Mountaineer - The Story


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Part I

Imagine a machine that stood as high as a 16-story building that was still able to move by its own motive power. A machine that had an operating weight of 2570 tons, swung a 65 cubic yard bucket that took 100 ton bites of earth and rock, and moved it over the length of a football field to place it on top of a giant spoil pile. The official designation of this stripping shovel, the correct name of such a type of machine, was type 5760 and was manufactured and erected by the Marion Power Shovel company during 1955 / 56 near Cadiz, Ohio. This behemoth was better known under its unofficial name, the Mountaineer.

The Mountaineer was the first machine of a series of giant stripping shovels, a specific type of excavators that were used between the late 50s and about the 70s (some of them are still working today) for uncovering coal in the rich coal fields in the United States.

In strip mining operations, coal is uncovered in a straight and long pit by removing the overburden over the coal seam. When coaled out, a second stripe is opened and the overburden of it is used to fill back the first one. This is the duty of stripping shovels.

All large stripping shovels consist of a lower carriage with a set of two crawlers at each of its four corners. Connected to the lower carriage, with the help of a large turntable, is the upper carriage that carries the boom, the gantry (the A-shaped frame atop the upper carriage that supports the boom), the stick and attached dipper, and the machinery.

All shovels were driven electrically, and had a large extension cord, or umbilical, that fed the machine with alternating current. This current powered AC motors that drove DC generators. The generators produced current for the motors of the main functions of the shovel: drive of the crawlers, swing motion, hoist winch, and crowd mechanism. This combination of AC motors and DC generators is called MG sets (motor generator sets) or Ward Leonard control.

There are two principles how the dipper and stick are mounted to the upper frame of stripping shovels. First, there is the variant of a large bearing about half way up the boom in which the stick can glide forth and back. In this case it is powered by means of ropes that run over the crowd drum.

The second variant uses a stiff leg that is hinged at its lower end between the two legs of the A-shaped boom. At the other end attaches the stick of the dipper and a gear rack that provides the crowd motion by means of electric motors that are mounted up in the gantry. The Mountaineer uses the last principle.

Stripping shovels are usually operated by a crew of three, 1) the operator, 2) the oiler, responsible for keeping the machine working and keeping it clean, and 3) the ground man that moves the machine in the pit and is responsible for the power cord. Often the ground man operates an auxiliary piece of equipment like a bulldozer or a wheel loader to keep the work area level and clear of rocks that sometimes roll down the spoil pile.

Beside the basic functions, there are a lot of other less important features that can be found on stripping shovels. One of them is an elevator for the crew that allows them to safely reach the machinery and the control cab (the Mountaineer was equipped with two cabs so that the operator could chose the side where he was dumping).

The elevator was boarded in the lower carriage and then passed through the king pin, the name of the center of the turntable, to reach the machinery deck. The Mountaineer was the first machine to be so equipped and all subsequent stripping shovels of both major stripping shovel manufacturers, Marion Power Shovel and Bucyrus Erie, featured an elevator.

This elevator is the reason why I decided to build a model of the Mountaineer. The first pictures of stripping shovels I found in books. Later, I searched for information about these machines on the Internet and soon found stripmine.org, a site dedicated to large mining equipment. Members of the Stripmine community later would help me a lot in gaining information for my project - many thanks to them!

The first model of a stripping shovel that I built was the Bucyrus Erie 1050B. It incorporated the turntable that I originally developed for a walking dragline model that I never realized due to a lack of parts.

Although the turntable worked very well, I decided to develop a version that uses no standard Technic turntable as king pin. I had the idea of building one that would allow an elevator to pass through it, but I didnít know how to build it.

First, there had to be a big hole in the center of it, but the different parts of the turntable still had to be guided about the center of rotation. Four quarter circle parts would form a perfect circle with a diameter of eight studs.

This circle fulfilled two goals. First, there was a big hole and it could be used to guide the upper part of the turntable against the lower one. This I realized by placing four pins on a square so that it would perfectly fit into the circular shape created by the four quarter circle parts.

Now that this problem had been solved there was an even bigger challenge: how to motorize it. A standard Technic turntable can easily be motorized by a driven gear engaging with the teeth of the gear ring of the turntable, but my new solution did not have a gear ring.

I found two solutions to motorize my device. First, there was the idea of a string that is wound around a cylinder concentric to the turntable. This string is also wound around a drum. By revolving this drum it would roll around the big cylinder and therefore move one part of the turntable against the other one. This has the disadvantage that it is not possible to do a full 360 degree revolution because the string has to be fixed at some point on the big cylinder.

The next idea that led to success was to build my own gear ring that is big enough to be placed around the circular center of the turntable. There are only three things that work together with LEGO gears: other gears, gear racks, and crawler links. This was the solution! Using crawler links that form a closed circle with which gears could engage to drive the device. I used the first generation of crawler links made by LEGO, the ones with two studs on top and the corresponding red nine tooth gears. They could be easily connected with other parts. The final solution can be seen in the Building Hints section under Heavy Duty Turntables #2

Of course the turntable was not yet finished. There had to be a roller ring like on my first version to support the weight of the upper carriage. Using the same principle led to a ring with 64 rollers and a diameter of 48 studs.

Now I had the turntable that was able to let an elevator pass. The only thing missing was the stripping shovel around it. When I am selecting a prototype to model with LEGO bricks, I always chose one that can either be built in its original color scheme or that looks good in different colors that are provided by The LEGO Company.

When collecting LEGO bricks for quite a long time you will have a lot of red, white and black basic parts like bricks, plates and slope bricks. These colors were the most used in official LEGO sets some ten to twenty years ago.

The true colors of the Mountaineer are as follows. The lower carriage is painted black as is the gantry. The machinery house is (from top to bottom) white, red and white again. The boom, stick and the stiff leg of the crowd mechanism are painted red.

The decision was made, I would eventually build the Mountaineer. What contributed to this decision was that there were quite a lot of pictures available of this machine in comparison to other large stripping shovels. By the way, the original color scheme was later changed to yellow and orange to fit the new corporate image of Consol, the company that had run the Mountaineer.

This is certainly because the Mountaineer was a very famous stripping shovel and the first machine in this size class (when talking about excavators, size is measured by the dipper capacity). Unfortunately it is impossible to get blueprints of such equipment so that I will have to take all measurements and proportions out of pictures and written descriptions.

The size of my project was easy to estimate. The turntable measures 48 studs in diameter and therefore the stripping shovel will be modeled around it. This resulted in a calculated scale of 1 / 28.125 and results in a boom length of 1.63 meter according to measurements given in books.

Then, I laid down the features the model shall have:

In addition, I planned to build a bulldozer for the groundman and some other equipment as a comparison to make observers aware of the size of a stripping shovel in reality.

At this time, I was in doubt for the first time as to whether I would have enough parts and whether the weight would become too big. I have had problems with the weight of models before (e.g. resulting in axles that bent too much and therefore made it impossible for a crane model to stand on its own wheels).

My first stripping shovel model showed problems with steering under its own weight, although it only weighed 8.2 kg. I opted for a stronger mechanism and two old 9V motors instead of a single new one in the Bucyrus Erie 1050B. Because the Mountaineer would be about twice as big in every dimension, the weight would be much higher as in any model of any kind I built before.

Nevertheless I started construction. Part two will describe first results.

Move on to the second part of the story

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