The Rocker Shovel Loader 12B provided a significant boost to underground mining productivity by emulating the movements of the human “mucker,” the laborer who removed rubble, or “muck,” from underground mines, particularly in and narrow mine tunnels.
Designed in the late 1930s by Edwin Burt Royle and John Spence Finlay, employees of the Anaconda Mining Company, the first working machine was called an “overshot loader.” Both men worked for the North Lilly Mine in Ureka, Utah, in the 1920s and early 1930s. Apparently prior to 1931, their machine had a heavy bucket attached to a rail car by two moveable rocker arms, and the car had air-motor powered wheels to push it into the rubble. In 1931, Joseph Rosenblatt of EIMCO, Salt Lake City, met Royle and Findlay, and shortly thereafter, Royle joined EIMCO as a consultant and designer. Where the first machine had been constructed from discarded Model T parts, EIMCO then developed it into the Model 12B that sold thousands.
The loader was operated by a worker at the side of the machine who could manipulate two controls, one for the wheels and the other for bucket travel. It was run entirely by compressed air. As the machine moved forward, the bucket (with an operating capacity of four to six cubic feet) was capable of removing up to 30 cubic feet of rubble per minute. When the bucket was full, an operator would actuate the bucket drive motor that would move the rubble upward and rearward into a mine car for removal.
Source: The American Society of Mechanical Engineers
