A simple description.
Most all of us have seen draglines or, to be more precise, dragline excavators. We have either seen the dragline or pictures of draglines. In the mining industry, the use of draglines are common and most are huge machines. Basically, there are two types of draglines and to put it simply, there are (1.)The Large Dragline, and (2)The Small Dragline. Add a different type of "Bucket", Clam, Clamshell, etc. to the hoist rope and do away with the drag rope and you have a crane or a derrick. The drag rope and the scoop or bucket are the main differences between a dragline and a crane. These machines are very versatile.
This short series on dragline excavators will consist of information about the large dragline excavators and of dragline excavators used in the mining industry. In the following paragraphs, the dragline excavator will simply be called a dragline. As previously stated, the draglines used in mining are enormous and have to be built "on site" as there are very few means of transporting a large strip mining dragline. Just their weight alone prevents them from being transported by normal means. Most must have some type of a base to just sit on as if on just dirt they would mire down where they could not be moved. Oh there are draglines that can be transported by trucks and other means, but these are of the smaller type. Guess to categorize draglines; if it can be transported to another site without disassembly then it is a small dragline and if not, it is a large dragline.
Some of the earliest know iron works are from Egypt that date back to 3500 BC. Iron will rust and thus, very few remains of early ironwork exist. Wrought iron beads, for decorating purpose, exist that came from Jirzah in Egypt and have been dated to the era of 3500 BC. It would be some 1500 years later before the smelting and purification process of iron ore would be discovered and then cast iron could be used for larger projects such as tools and weapons.
Early man used different materials to move dirt typically bones from animals including the shoulder bone of man. Crude shovels made from bones and wood date back hundreds of years. With the knowledge of making cast iron opened up all sorts of tools and weapons including a shovel. The shovel or spade made of iron was a big improvement over the earlier tools made from other materials. Soon man learned that a scoop could be made, and attached to a prime mover like a team of oxen, and with this configuration being used, a lot of dirt could be moved.
Maybe by definition, the simplest form of a dragline is some form of a pull rope being pulled toward a person or a device. Hence, a drag line. Add a scoop to this pull rope and you have a simple dragline excavator. A man or a group or men could pull a small scoop, but the amount of scooped contents would not be worthwhile. Harness this small scoop to a horse, a team of oxen, or other draft animals and a simple dragline operation is in the making. Add some handles to this scoop attached to a draft animal and a person could control the scoop by manipulating the handles. Now, some dirt could be moved. Some of these small scoops, maybe a third of a yard in size, are in use today. This scoop, or scraper, being pulled by a horse or other animal(s) is placed in the scoop (dig) position by manual power from the operator walking behind the scoop and when full, the operator pushes down on the handles to place the scoop in the pull position. Now, by using the harness attached to the draft animal, the operator can move the scoop of material to another location. By lifting up on the handles, the operator can dump the load and place the scoop back in the "Move" position. Now back to the "Dig" area for another scoop. Three of these scoops are pictured just to the right of this reading material.
A lot of dirt needs to be moved to uncover coal and other minerals that exist just below the surface of the earth. To move a lot of dirt and overburden for a mining operation, a large scoop and a means of moving that scoop much be made. In 1794, John Street patented an internal combustion engine and four years later, John Stevens designed the first American internal combustion engine. In 1823, Samuel Brown patented the first internal combustion engine to be applied industrially. Then in 1892, Rudolph Diesel, a German engineer created the diesel engine, a type of internal combustion engine. Overall, various scientists and engineers contributed to the development of internal combustion.
With the event of the internal combustion engine a new form of a drag line could now have enormous pulling (drag) power. Wind a wire rope with one end attached to the scoop and the other around a stationery drum and attach the new power mover, the internal combustion engine, and pulling power would now only be limited to just how large a motor was built. To complete a dragline, we now add a boom with another wire rope attached to a "Hoist" motor, and threaded through pulley(s) at the top of the boom and on down to the lifting and dumping part of the scoop. Add a "Swing" motor(s) to the machine and attach this swing motor(s) through a gearing mechanism and now the dragline can be revolved on it base. This permits the "Boom" attached to the scoop or bucket to be able to "Dig" in one area and then "Dump" in another area. Add a walking mechanism powered by other motors and the dragline now has the ability to move. It moves very slowly, but it does move. The newer and larger draglines use electric motors instead of internal combustion engines. These large motors are powered by an electric cable much like an extension cord that one would use at home. Plug the cord into a "Hot House" and dig until you run out of cord. Then plug into another strategically placed "Hot House". The cable is a tad larger than the household extension cord and the voltage is much higher.
And along came Mr. Page, the invertor of the modern day dragline. But that is another story. Check this out under the heading of "Page" Draglines. Link Below:
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Thanks for looking and reading.
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