Air Compressors are machines used to generate compressed air. The most common types of air compressors used are piston and rotary screw positive displacement compressors. A positive-displacement compressor works by forcing air into an air chamber whose volume is decreased to compress the air. A piston style works by moving a piston up and down. In the down motion, it compresses air. A rotary screw turns a compressor screw inside of a cylinder thus forcing air into the chamber by the screw motion. We rep used air compressors from Ingersoll Rand and Kaeser.