A control system for use in a vehicle having left and right clutch assemblies, each including a brake mechanism and a drive mechanism. A pair of pinion drive gears engage with gear teeth of the wrench gear at spaced apart locations on the periphery so that at least one of the pinion drive gears is engaged with the wrench gear at all times during rotation of the wrench gear to tighten the one nut. The carrier is adapter to be moved through the ducts of a pneumatic delivery system without becoming stuck in the system.