It has been said many times here in these pages that the hoist was the heart of a mine. The life blood of copper flowed by the power of these steam behemoths. Often a mine’s most expensive purchase was their hoist engine, and it was the center of attention. Impressive arrays of support buildings were assembled just to service them and keep them running. The men who operated them viewed them with pride, and the company that owed them made sure to keep them spit and polished and the buildings that housed them clean and neat. Later, the men who worked the underground would trust them with their lives, as they road down into the underground on man cars. The life of a hoist was a good life indeed.
It seems fitting that often the first sign of a mine that we find hidden in the woods is the remains of the buildings that once housed these important machines. They are very easy to recognize, as was the large example we came across at North Kearsarge No. 3. Its outer walls of poor rock were relatively intact, and within them sat the impressive blocks of brick and sandstone which formed supported the hoist itself. The hoist was of course long gone, but the remains that we found gave us a good indication of what it once looked like.
There were many different types of hoist engines in use throughout the Copper Country’s history. The most common, especially in the late 19th century in which this mine was born, were “American type” horizontal engines. These engines placed the pistons horizontally, instead of the vertical alignment of older engines. Steam is admitted into a closed cylinder containing a piston. As the steam expands the piston is driven forward. Then steam is admitted onto the other side of the piston (known as a double-action piston) which pushes the piston back into its original position. This back and forth motion is transfered through a connecting rod to a crank. The crank turns a drive shaft, which in turns drives the hoisting drum. The rotation of the hoisting drum lets out or winds in hoist rope – lowering or raising rock from the underground.
Most hoists used in the late 19th century had two cylinders working in tandem to turn the hoist drum. Above you can see an example of a typical engine. This engine was a 2500 horsepower E.P. Allis Hoist used at Quincy No. 2, built in 1894. This would be similar in design to most hoists in use at this time, including at North Kearsarge. This engine ran at 32 rpm and was capable of hoisting a skip at a rate of 3000 feet per minute (about 34 mph). It was controlled by an elevated platform sitting behind the drum.
These massive machines were supported by equally massive foundations. Normally they can be recognized today by their distinctive “H” shape. (Check out our post on the Osceola Hoist ruins and the remains of that foundation here to get an idea) The legs of the “H” supported the cylinders, pistons, and drive collars. Between the upper legs of the “H” sat the hoist drum itself, sitting down a few feet below the cylinders. In the space at the bottom of the “H” would sit the steam pipes and manifolds use to feet the cylinders. All along the length of the legs are wood-incased threaded rods which once was used to mount the engines to the foundation. These were the things we found at North Kearsarge.
Tomorrow: Hoist Ruin Details…
Hoist diagram and photo courtesy Historic American Engineering Record, American Memory Collection, Library of Congress