Itt Industries, Inc.

Peter Riedel

Hans-Henning Lupertz

Lucas H Haar

A light weight brake booster is disclosed having an internal axial tube for transmitting axial forces with a working or boosting piston surrounding the tube and a control piston slideably guide inside the tube. These two pistons are connected by reaction levers extending through longitudinal slots in the tube. The reaction levers are pivotably supported to transmit boosting forces to a master brake cylinder and their inner ends engage the control piston to deliver a reaction force to the brake pedal to give the driver the required 'brake feel'.

Mechanically controlled vacuum booster

In a known tandem master cylinder with a regulator, machining and assembly of the parts is complicated which renders the master cylinder costly. Moreover, such an arrangement is only realizable with master cylinders having a large diameter. There are also functional disadvantages, particularly in the event of failure of one brake circuit, the brake fluid volume consumption of the other brake circuit is materially increased which results in an additional increase of the pedal travel. To avoid these shortcomings, the present invention provides a tandem master cylinder with a regulator including an arrangement, which in the event of failure of the front-axle brake circuit, mechanically actuates the regulator valve coupled to the rear-axle brake circuit by a pressure piston to keep the regulator valve in the open position to enable unreduced braking pressure to be coupled to the rear-axle brake circuit.

Tandem master cylinder

In a known tandem master cylinder with two regulators for use in vehicles using diagonally split brake circuits, machining and assembly of the components is time consuming which makes the device expensive to manufacture. Moreover, the arrangement is only realizable with master cylinders having a relatively large diameter. There are also functional disadvantages, particularly that in the event of failure of a brake circuit the fluid volume consumption of the other brake circuit is materially increased which further increases the brake pedal travel. To eliminate these shortcomings, the tandem master cylinder with two regulators of the present invention includes means which, in the event of failure of a brake circuit, the regulator valve of the other brake circuit is actuated mechanically by one of the pressure pistons so that the regulator valve of the intact brake circuit is kept open to enable unreduced braking pressure to be coupled to the intact brake circuit.

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Hattersheim, Germany

Peter Riedel