Designs have been proposed for cross vehicle beams for absorbing impacts to the side of a passenger compartment. It is an object of this invention to provide deployable (including extendable/retractable) telescoping tube beam systems for this purpose. It is a more specific object of this invention to provide such a telescoping tube beam system that uses a conical piston-retained ball mechanism in energy absorption. It is a further object of this invention to provide a method of operating an extendable/retractable embodiment of such deployable beam systems.