Abstract: A brake system for an automobile comprises a planetary gear set, a clutch operating unit and an emergency braking unit. The planetary gear set is disposed between gear and clutch assemblies of the automobile and includes a bell-shaped casing with a central neck connected securely to an input shaft of the gear assembly. The bell-shaped casing has an annular wall portion with an internal thread therein, a sun gear disposed centrally in the casing and fixed to a clutch shaft of the clutch assembly which passes axially and centrally therethrough, and a planet gear which meshes with the internal thread of the casing and the sun gear. The planet gear has a planet shaft connected rotatably to a clutch shell of the clutch assembly.