English to Spanish Tech/Engineering Mechanics / Mech Engineering railroads, trains

I need help with this one because I find so many translations, all different.
Context:
tapered roller bearing units TAROL
are compact, ready-to-fit rolling
bearings which have been greased,
sealed and adjusted for axial
clearance. They can be pressed
onto the ***shaft journal*** in a single
operation. If the ***shaft journal***
diameter is within the specified
tolerance,...