An integrated welder, generator and compressor unit that includes a housing that at least partially contains components of a welder, generator and compressor. An engine, an electric current generator, and an air compressor are at least partially mounted in the housing. The electric current generator is at least partially connected to the engine to be at least partially driven thereby. A drive connector at least partially connects the air compressor to the engine and/or electric current generator. The drive connector includes a gear box that has at least one gear.