Xav txog kev qhib lub qhov rooj tsheb rau ib tus qhua tseem ceeb - nws yuav ua tau txawv txawv yog tias lub qhov rooj sab nrauv tau rov qab nrawm nrog lub suab nrov. Hmoov zoo, qhov no tsis tshua muaj tshwm sim vim hais tias feem ntau cov qhov rooj sab nrauv yog nruab nrog rotary dampers. Cov dampers no xyuas kom meej tias tus kov rov qab ntsiag to thiab du, txhim kho tag nrho cov neeg siv kev paub. Lawv kuj tiv thaiv tus kov los ntawm kev thim rov qab thiab ua rau cov neeg caij tsheb raug mob lossis ua rau lub cev puas tsuaj. Lub qhov rooj sab nrauv yog cov khoom siv tsheb feem ntau uas siv cov dampers teb.