Abstract: A brake system including an apparatus for limiting drive slip at drivable vehicle wheels by feeding brake pressure into wheel brakes associated with these vehicle wheels. The brake pressure is generated in a pressure modulator having a spring-loaded stepped piston including a primary piston. The primary piston can be acted upon by pressure fuid from a supply container by a motor which drives a pump. A secondary piston of the stepped piston effects the brake pressure and feeds it via a valve assembly into a brake line extending between the master brake cylinder of the brake system and a wheel brake. The brake pressure can be diminished by controlling the drive motor of the pump. The pump is embodied with reversible pumping directions, and the pressure fluid flows through it both during a working stroke and a return stroke of the stepped piston. The valve assembly is actuatable by the stepped piston as a function of the position thereof.

Abstract: The brake system has an apparatus for traction control having a pressure generator. The pressure generator has a longitudinally displaceable cylinder for receiving brake fluid. The cylinder is connected by means of a valve to a pressure course between a master brake cylinder and a wheel brake cylinder. An actuating element is provided for closing and opening the pressure course to the master brake cylinder as a function of the cylinder position. The actuating element, extending coaxially between the cylinder and the valve comprises a tube and furnishes hydraulic communication between the cylinder and the valve. If excessive drive slip occurs, brake fluid can be positively displaced out of the cylinder by longitudinal displacement thereof, and brake pressure can be generated in the wheel brake cylinder. The actuating element assumes a piston function, which enables a structure of the cylinder having a smaller diameter and a long stroke. This makes for more accurate adjustment of the brake pressure.