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The air drill is one of the most important inventions in the construction business of all times. Before the invention of the pneumatic drill, the task of drilling rock was very tedious. It was usually done with a team of 3 men. Two men would hammer the rock drill taking alternate swings with a heavy sledge. The third man would hold the bit and turn it a part of a turn between hammer blows. A good team could drill 12 inches a day in hard rock. It was small wonder that the railroad companies of the 19th century made slow progress in construction when they were drilling rock by hand. A Gardner Denver 600 Cubic foot air compressor and Chicago Pneumatic trac drill such as you see here will drill a 10 foot hole in solid basalt rock in a few minutes. This compressor features a Cat 333 Engine and a rotary vane compressor. Detroit Diesel engines are actually far more common in compressors of this vintage which dates back to the 1970's. Rock drilling and the blasting that follows is still expensive, however, and this is why you see increasingly large bulldozers around. Bigger, heavier dozers will handle rock conditions that smaller dozers simply won't handle. For example, the site you see here required blasting in 1974 when it was being worked with an HD21 Dozer, but when the Fiat Allis 31 (nearly twice as large) became available, this same location could be worked by brute force without blasting.
Featured on the right is a LeRoi Tractor Drill. It is a combination Tractor, rock drill and air compressor all in one. The 6 cylinder engine has 4 cylinders for running and 2 additional cylinders which constitute a 100 foot per minute piston air compressor. It is obviously a much smaller less productive drill than the 600 FPM operation. Also shown here is an early 1950's version of a Jeep Pickup. For many years these Jeeps were the only alternative to the Dodge Power Wagon if one wanted or needed a 4-wheel drive pickup. This pickup used the same 4 cylinder engine and transmission assembly found in classic Jeeps. Needless to say a whole industry existed based on substituting other engines.