English to Spanish Tech/Engineering Mechanics / Mech Engineering

Load must be equally distributed about
the centerline of the strongback

The total load must not exceed the capacity
Of the strongback or the crane to which
It is attached.

Slide brackets must be positioned so the
Lifting slings or other lifting devices are
Vertical when lifting the load.

I don't have more information than this. I need the translation for "the centerline of the strongback" in Mexican Spanish if possible. Thanks.