How do I prevent parts passing through one another? Assembly

How do I prevent parts passing through one another? Assembly I have created a damper, the constraints that I have used are pin for the axis of the piston with the centre of the top part of the damper, allowing me to slide the damper back and forth, but the problem that I have is that the piston can still pass through the top part of the damper when I move it. You can limit motion in a number of ways, depending on constraints, such as distance or angle. But in some later versions of Pro/e with Mechanism Design, isn't there something like the SolidWorks collision detection which will simply stop the part? I don't know if it's a default or maybe it has to be "turned on" with an option in 'Tools>Options'? Not an answer but possibly a direction.

David Janes