Used Midi Excavators for Sale. Excavators are one of the most important types of heavy machinery, and come in every size. Midi excavators weigh 7-12 tons and are used for jobs requiring good power with great maneuverability. We have used Caterpillar midi excavators, Volvo, Komatsu and more. Not sure if the midi size is right for your job? Please contact our used equipment experts for free advice.