I am working on a simulation of an assembly that is tied down to a floor. I assumed a frictionless floor and applied a roller fixture to the entire base of the assembly. When I applied a substantial inertia load to the assembly against the tie-downs, I expect the case to want to lift off the floor somewhere just from deflection of the base. However, the base of the assembly remains totally flat, almost as if it were restrained from moving vertically up. I would expect the roller to restrain the face from moving vertically down, or penetrating the floor. I noticed the roller fixture symbol is a simple arrow whereas a fixed geometry symbol is an arrow with a base. This indicates to me that a roller restrains it in one direction on that axis whereas the fixture restrains in both directions on that axis.

Is my understanding of this type of fixture accurate?