Engine-driven mechanism for supplying high pressure air to truck brake systems. There are basically two types of compressors: those designed to work on in-line engines and those that work on V-type engines. The in-line type is mounted forward and is gear driven, while the V-type is mounted toward the fire wall and is camshaft driven.A gasoline engine or electric-motor-driven mechanism for supplying shop air for the lift, air tools, and paint spraying equipment.