The easiest way to farm gears is to start a Skirmish game as Alliance vs Alliance, in Close mode, under the Hard difficulty setting. At the start, use Miners until you hit the unit limit. Then, upgrade Fighter Hull and Weapon to level 2. Next, use Fighters until you win. Help your Fighters with Repair and disable enemy units with EMP when possible. You should win a Skirmish game in about two minutes, and earn 5 gears in addition to those found on the battlefield when you kill an enemy unit.