I may not be understanding your question. As near as I can tell, you are asking one of two questions.
Question 1: You are loading a single file, such as
gears.stl that contains 2 gears, and you want to apply separate transforms for each of the gears. ParaView cannot do this because it doesn’t know what a “gear” is. You first have to split the data into two objects. There might be ways to do this, but we would have to know more about your data.
Question 2: You have two separate objects, such as loading a file
gear2.stl, and you want to rotate each around its own center. The problem is that when you apply a
Transform it always rotates around the center of the world instead the center of the object. Unfortunately, there is no way (that I know of) to change the center of rotation for the
Transform filter. There is, however a trick by using a sequence of 2
Transform filters. Have the first
Transform filter translate the object to be centered at the origin. Use the second
Transform to do the actual rotation and also set the translate back to its original position.
If you have further questions, it would be helpful if you could post an example of your data. That would give us a better idea of what your problem is and how it can be fixed.