Hi Henk,

From my understanding every parts in MultiBody library have at least one frame attached. Refer to The New Modelica MultiBody Library for more detail description.

Say you are using a Bodybox(like a beam) in Parts folder, then you can attach Force/Torque on both ends and the force and torque can described in either frame. If you want to have force not at the ends of the beam but in between ends, you need to attach a fixedtranslation to translate coordinate so that force can act on other positions of the beam.

Yuchen