Over 450,000 tons of rock were removed from Mount Rushmore to bring out the four presidential faces. Although about 90% of the rock was removed with dynamite, the remaining rock was removed by drilling with jackhammers and wedging the rock off the mountain. The final finishing work on the faces was completed using small jackhammers and facing bits. Air compressors located here at the base of the mountain provided the power to operate the jackhammers.
The Ingersoll-Rand Imperial Type 10 Air Compressor displayed here was the largest of three in operation in the compressor house which stood at this location during the carving work. For much of the life of the carving, Keystone Consolidated Mines provided the electrical power to operate these compressors.
An 1,800-foot, 3-inch pipeline followed the stairway up the mountain to carry air for the jackhammers from the compressor below. In cold weather, a liquid gas was injected in a fine mist into the pipeline beyond the compressors to prevent freezing. The pipeline was later enlarged and expanded to provide compressed air to more jackhammers.
In 1936, Julian Spotts, a National Park Service engineer, checked this system for leaks. He discovered the blacksmith had tapped into the line with a nozzle to blow compressed air on himself while he worked! Spotts provided a fan instead.
Spotts also tried to discover the reason for a large power loss suffered at Rushmore every Monday morning. "Well, I found," said Spotts, "that just about every woman in Keystone washed clothes on Monday, and a lot of them had electric washing machines." Instead of trying to rearrange Keystone's laundry schedule, Spotts asked the Mount Rushmore Commission to buy a gasoline-powered auxiliary compressor. "And after that," according to Spotts, "we had no more power problems." These improvements increased the minimum number of jackhammers that could be operated from 16 to 22.
Black Hills Power and Light completed a power line to Rushmore in 1939. This provided all the electricity needed for the remaining two years of carving work. Today, this compressor and sections of pipe still in place on Mount Rushmore stand as testimony to the power it took to carve a mountain.
Comments 0 comments