From the mid 1960s through early 1970s, Marion Power Shovel developed the Superfront shovel front to increase the digging force and efficiency of a shovel dipper. Also in the mid 1960s, Bucyrus-Erie developed a competing design, the Doubler. Developed by Heckett Engineering, the Doubler was said to double the shovel’s capacity.
Like the Superfront, the Doubler brought the shovel’s operating weight and digging force closer to its center of gravity, reduced digging stresses and allowed for digging in a level plane rather than an arc. Digging force was increased by causing the hoist and crowd motions to work together, where on a conventional shovel the two motions worked against each other in the lower portion of the digging range.
The major difference between the Doubler and the Superfront was in how the front operated. The Superfront was entirely cable operated. But the Doubler used hydraulic cylinders to provide the dipper wrist and hoist action, allowing the shovel to dig higher up on the bank if need be.
From 1968 through 1970, Bucyrus-Erie sold three Doublers. Two were converted from standard 150B loading shovels, and one was a larger 190B. It was also offered for the 280B, but none were produced. Capacities ranged from 13 cubic yards for the 150B to 26 for the 280B.
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