P&H dragline at Pioneer Park represents early 1900s industrial innovation
When gold was discovered in Alaska at the end of the 19th century, it was individual miners who initially exploited the resource using picks and shovels and other rudimentary equipment. As easy diggings disappeared, individuals were supplanted by companies with the necessary capital to invest in more-efficient, large-scale gold recovery methods.
These larger-scale operations were aided in the early 1900s by new innovations in earth-moving technology. For instance, incremental improvements to internal combustion engines during the latter 1800s gradually led to smaller, more powerful engines that eventually replaced steam as the motive power in many industrial applications. At the beginning of the 1900s mechanized mining equipment such as hoists and tractors were powered by steam. However, by the mid-1910s bulky steam engines were being replaced by smaller diesel and gasoline engines.
Coupled with improvements to internal combustion engines was the development of continuous-tracked vehicles, the culmination of decades of tinkering. The first usable crawler-tractors began appearing in about 1907 and quickly found a niche in the mining industry.
Another important innovation was the dragline excavator, commonly just called a dragline.
A dragline is an earthmoving apparatus in which a bucket is suspended by cables from a movable boom. The boom, in turn, is mounted to a chassis housing an engine and control cab. Small draglines were commonly mounted on tracks or the back of trucks.
In operation the dragline bucket is maneuvered into position and then lowered to the ground and dragged along the surface, scooping up material. The full bucket is then raised and emptied into a truck bed, train car, or hopper; or dumped at another location. Separate cables are used to position the boom, raise and lower the bucket, and drag the bucket across the ground.
According to a Wikipedia article on dragline excavators, skilled dragline operators could throw or “back-cast” a bucket farther than the end of the boom. By pulling the suspended bucket towards the cab and then releasing the drag cable, the bucket would swing like a pendulum. Once the bucket passed the vertical in its forward swing, the hoist cable was released, casting the bucket up to half-again the distance from the cab to the end of the boom.
Draglines were developed in the first few years of the 20th century and by 1910 several U.S. firms were manufacturing them. Those first draglines were powered by steam, but a history of the P&H Mining Equipment Company (started by Alonzo Pawling and Henry Harnischfeger) states that in 1914 the company introduced the first gasoline-engine-powered dragline.
Draglines like the small P&H Model 150 shown in the drawing (now in the Mining Valley at Pioneer Park) were once common at placer mining operations around Alaska. Unfortunately, many of Pioneer Park’s records were lost during the 1967 flood, so little is known about the park’s dragline.
P&H’s Model 150 was a small dragline manufactured between 1937 and 1952. It weighs about 15 tons, has a 30-foot boom, and a 5/8-cubic-yard bucket. Other manufacturers, including Bucyrus-Erie and Insley, produced similar draglines.
Based on old photos in the Circle District Historical Society photo archives, it appears that draglines were often used in conjunction with bulldozers for loading hoppers on elevated sluice boxes. A 1996 U.S.G.S. report on Fortymile River placer mining states that mines using dragline-bulldozer-hydraulic combinations were active in the 1950s, and that draglines were utilized at least into the 1970s.
In modern small-scale placer mining operations, draglines have mostly been replaced by front-end loaders and backhoes. Small draglines are no longer manufactured, and for the most part, the only operational draglines are giants such as Usibelli Coal Mine’s 2,100-ton “Ace-in-the-Hole” dragline at Healy.
- “A History of P&H Mining Equipment, Inc.” P&H Mining Equipment, Inc. No date
- “Dragline Excavator.” Wikipedia. 12-21-2020
- “Gold Placers of the Historical Fortymile River Region, Alaska.” Warren Yeend. U.S. Geological Survey. 1996
- Photos of draglines in operation, in the Louis Smith collection of the Circle District Historical Society photo archive.