A power transmission for an all-wheel drive earth moving truck of the off-highway type. More specifically, an inter-axle friction clutch biased differential with automatic clutch release for such a power transmission. The differential is equipped with a clutch which provides a predetermined amount of torque differential, or bias, between the two shafts that drive the front and rear wheels, for thereby accommodating slipping conditions. The amount of differential or bias torque is determined by the load capability of the drive train which is located downstream of the differential. The clutch serves to protect the drive train from excessive loads in that, when the predetermined torque value is attained, the friction clutch will slip. Thus means are provided for sensing the slip of the friction clutch and for completely releasing the clutch before high speed slip values of the clutch are developed. Otherwise continuous slip of the clutch at high speed slip values and rated torque would cause failure of the clutch.