Of these various types of propulsion machinery, only the slow-speed diesel engine, which runs at about 100 to 200 r.p.m (revs per minute) - in extreme cases up to 300 r.p.m - acts directly on the propeller shaft.
Kwezi ntlobo ntlobo zeematshini eziqhubela phambili zii-injini zedizili ezinesantya esicothayo zodwa, ezibaleka malunga nekhulu ukuya kwamabini r.p.m. (ezizungulezi ngomzuzu omnye) kwimeko ezingaqhelekanga ukunyuka ukuya kumakhulu amathathu r.p.m. zisebenza ngokuthe ngqo kwisiqhubi mphini.