Mining Heritage Exhibition: The Air Compressor (photo diary )

The Mining Heritage Exhibition in Wallace, Idaho, is a four-acre historic park which operates exclusively through local efforts. The park displays mining artifacts and machinery from the area’s mining industry. One exhibit features the Ingersoll-Rand Air Compressor.

According to the display:

“This Ingersoll-Rand rope drive air compressor was installed at the Gold Hunter Mine near Mullan, Idaho in 1929.  Through a succession of mine owners and time, the compressor was replaced by modern air compressors.”

According to the display:

“The rope drive air compressor you see in this exhibit was built using patents from 1889 to 1904. It was probably built in the early 1900s and initially used in Butte, Montana in a copper mine.”

Shown above is an electric motor driving a 125-volt DC generator, commonly referred to as an exciter. It provided DC voltage to the rotor of the large low speed synchronous motor driving the compressor. AC voltage applied to the stator of the synchronous motor created a rotating magnetic field which drove the rotor and powered the compressor directly without the requirement of expensive and mechanically complicated speed reducing equipment.