A sequential lift, nozzle valve control bar on a turbo generator, utilizes which of the following operating principles?

Correct Answer: Option B — A lifting beam mechanism engages nozzle valve stems of varying lengths.

Sequential lift nozzle control bars utilize a heavy lifting beam with staggered or stepped adjusting nuts. As the beam moves, it engages valve stems of varying lengths sequentially, opening individual poppet valves to regulate steam flow economically.