An air compressor unit having an enclosure with a base. A motor is rigidly mounted to the base, and the motor drives both an airend and an impeller. The airend is pivotally mounted with respect to the base. The airend is directly connected to a horizontal separator tank, and the separator tank supports the airend. The airend and separator tank comprise a single integrated unit, and the separator tank is pivotally mounted to the base. The motor is a dual shafted motor having a drive side shaft and a non-drive shaft extending from opposite ends of the motor. A drive system is coupled to the drive side shaft and transfers power from the motor to the airend. The drive system is a belt and pulley system, and the airend is pivoted with respect to the motor to adjust belt tension. The impeller is coupled to the non-drive side shaft.