Patent ID: 8523738

Claim:
A method of shifting a power distribution unit for a vehicle from a first operating state to a second operating state, the method comprising the steps of: drivingly engaging a first axle assembly with a first output of the power distribution unit; drivingly engaging a second axle assembly with a second output of the power distribution unit; drivingly engaging an input of the power distribution unit with an output of a power source, the power distribution unit including an inter-axle differential, the first output, the second output, and a first clutching device having a first position and a second position, the first clutching device in the first position locking the inter-axle differential, engaging the first output with the input of the power distribution unit, and disengaging the second output from the inter-axle differential, the first clutching device in the second position unlocking the inter-axle differential and engaging the first output and the second output with the inter-axle differential; placing the first clutching device in one of the first position and the second position; applying a rotational force to the input of the power distribution unit; adjusting the rotational force transferred to the power distribution unit to facilitate moving the first clutching device; moving the first clutching device from one of the first position and the second position to a third position, the first clutching device in the third position neither locking the inter-axle differential nor engaging the second output with the inter-axle differential; adjusting a rotational speed of the input of the power distribution unit to facilitate moving the first clutching device from the third position; moving the first clutching device from the third position to one of the first and second positions; and adjusting the rotational force transferred to the power distribution unit.