True four wheel drive system for vehicle

摘要

A drive train for a four wheel drive vehicle including a front differential engaged with a front drive shaft and front axles through a front differential gear set. The front differential includes a front bi-directional overrunning clutch that controls transmission of torque transfer between the front drive shaft and the front axles. A rear differential is engaged with rear axles and the transmission through a rear differential gear set. The rear differential includes a rear bi-directional overrunning clutch that controls torque transfer between the transmission and the rear axles. The differentials are configured with a gear ratio that is within five percent of a 1 :1 gear ratio.