The Tech Machine Shop was a civilian facility that could quickly manufacture almost any replacement part for vehicles. Military engineers may capture them to allow for the repair of land vehicles, ships and aircrafts all over the battlefield.
The more tech machine shops a commander owns, the faster the repairs. With one tech machine shop, the repair rate seem to be about 5% of a vehicles structural integrity every few tens of seconds. The repair ability will stack with self-repair ability granted by Elite veterancy or inherent self-repair capabilities, for instance, in the case of the Apocalypse tanks. With four or so machine shops, an elite apocalypse tank will be nearly invulnerable.
Many of these buildings were captured and used by various factions during the Psychic Dominator Disaster. Until they are captured, these buildings repair civilian vehicles and naval units.