Patent ID: 7644997

Claim:
A master cylinder with fill-up function, comprising: a master cylinder at least having a housing and two pistons slidably disposed in the housing and integrally moving at least in a forward direction, a pressure chamber and a fill-up chamber formed between the housing and the two pistons; a reservoir for accommodating a brake fluid from the fill-up chamber; a relief valve; and a coupled switching valve which is mechanically coupled with an advancing movement of the two pistons relative to the housing, and operates such that the coupled switching valve is in a first state in which is permitted a flow of the brake fluid from the fill-up chamber to the reservoir via the relief valve until the two pistons advance by a predetermined distance from a rearmost position, and placed in a second state in which is permitted a flow of the brake fluid from the fill-up chamber to the reservoir not via the relief valve when the two pistons have advanced by the predetermined distance or more, wherein there are provided two flow routes of the brake fluid from the fill-up chamber to the reservoir, the two flow routes being provided in one of: (a) one of the two pistons and (b) the housing, and the coupled switching valve is configured to switch between passing of the brake fluid through one of the two flow routes and passing of the brake fluid through the other of the two flow routes, mechanically coupled with the advancing movement of the two pistons relative to the housing.