ABSTRACT
When the acceleration of the base reaches -lg, the screw and base separate, and the screw continues in flight (constant acceleration) until it impacts the base. Since the screw impact is positive and the base impact is negative, the bottom portion of the threads of the screw contact the bottom portion of the threads of the base. This was referred to as a bottom impact. The first bottom impact is followed by at least one bounce (i.e., another flight and bottom impact). Each impact results in transient motions. After the last bottom impact and the resulting transients, the acceleration of the base and screw coincide until they reach -lg, at which point the cycle of motion repeats.
