Abstract: The present invention provides an input device of a vehicle brake system, the input device being a separate unit from an electric brake actuator, the electric brake actuator for generating a first fluid pressure, the input device of the vehicle brake system comprising: a master cylinder for generating a second fluid pressure; a stroke simulator for applying a simulated reaction force, the stroke simulator and the master cylinder forming an attachment body, with the stroke simulator disposed in communication with the master cylinder; and a component storage box provided on the attachment body for a component of either one of the master cylinder and the stroke simulator, wherein the attachment body has a vent hole with a first end in communication with the component storage box and a second end in communication with a space formed before a surface of a dashboard having the input device mounted thereon.

Abstract: An electric brake actuator (motor cylinder apparatus) for generating hydraulic brake pressure on the basis of at least an electric signal corresponding to brake manipulation by an operator, which is incorporated in a vehicle brake system with an input apparatus being arranged separately from the electric brake actuator and receiving the brake manipulation. A reservoir reserving brake fluid is attached to a cylinder body included in the electric brake actuator, and the ceiling of the reservoir is inclined from the axis of the cylinder body in correspondence with an arrangement of the main body inclined from the horizontal line.

Abstract: An annular sealing member 95 for establishing sealing between a boosted hydraulic pressure application chamber 22 and an input-side annular chamber 93 formed between a casing and a backup piston 64A and connected to a hydraulic pressure source is disposed between the casing and the backup piston 64A, and communication passage 216 for establishing communication between the input-side annular chamber 93 and the boosted hydraulic pressure application chamber 22 as the backup piston 64A moves forward by a predetermined stroke or more is provided in one of the backup piston 64A and the casing.