US Patent 10543825 Brake booster for a motor vehicle

A brake booster for a main brake cylinder of a motor vehicle includes a drive motor connected or connectable to a pressure piston for the main brake cylinder via a gear unit, where the gear unit includes a rotatable spindle nut, including a female thread and an axially displaceable, but rotatably fixed, spindle rod that includes a male thread, the male and female threads engaging into each other in order to convert a rotary motion of the drive motor into a translational motion of the spindle rod for actuating the pressure piston. The spindle nut is formed as two pieces and includes an inner part including the female thread and an outer part including an outer toothing, the inner and outer parts being made of different materials.