An interaxle differential unit and an axle assembly comprising an interaxle differential unit. The interaxle differential unit comprises an annular case and an interaxle differential unit gear nest. The annular case comprises first and second enlarged lips extending from first and second end surfaces, respectively. The interaxle differential unit gear nest is disposed in the annular case.

A method for monitoring and controlling open die forging processes, includes: a) calculating the geometry evolution of a workpiece during open die forging using empirical models; b) in parallel with step a), that is to say at the same time or at least partially overlapping times as step a), calculating the workpiece temperature across the cross-section of the forged workpiece; c) calculating the distribution of the change in shape over the length of the workpiece, preferably by using the geometry evolution calculated in step a); and d) manually or automatically controlling the distribution of the change in shape in a predefined region on the basis of the distribution of the change in shape calculated in step c).