Patent ID: 8851249

Claim:
A hydraulic brake master cylinder comprising: a cylinder unit including a first space, a second space, a channel communicating the first space and the second space, an outlet communicating the first space with the outside of the cylinder unit, and an adjuster exposed outside; a piston, provided with a guide hole and axially slidably disposed in the first space; a first spring, applying an elastic force to the piston; a rod, having a first end portion disposed in the guide hole of the piston in a way that the first end portion is slidable in the guide hole of the piston when the piston is forced to slide in the first space relative to the rod, and a second end portion disposed opposite to the first end portion; a second spring, applying an elastic force to the second end portion of the rod; a seal, attached to the rod, and moving controllably to seal the channel so as to block the first space from communicating with the second space; and a nut threaded onto the rod; wherein the adjuster is rotatable to make the nut and the rod rotate with respect to each other so as to change the distance between the seal and the end of the channel.