A hydraulic brake master cylinder, comprising:
- a body including a first cylinder, a first inner threaded portion, and a second threaded portion wherein the first inner threaded portion and the second threaded portion are arranged at two ends of the first cylinder respectively, and the first cylinder includes a first inner convex flange adjacent to the first inner threaded portion, and a second inner convex flange adjacent to the second inner threaded portion;
- a movable barrel passing through the first cylinder of the body;
- an outer convex ring disposed externally of the first cylinder, the outer convex ring radially and outwardly projected at one side of the movable barrel;
- a first outer threaded portion arranged on an outer surface adjacent to the outer convex ring;
- a fourth inner threaded portion arranged on an inner surface adjacent to the outer convex ring wherein the first outer threaded portion is rotatably and adjustably connected with the first inner threaded portion of the first cylinder, the fourth inner threaded portion is screwed with a fourth outer threaded portion of a first end cap, and the movable barrel further includes two flow-through holes relatively arranged and located between two ends of the movable barrel;
- a first piston including a large-diameter section and a small-diameter section connected with each other wherein the large-diameter section is inserted inside the movable barrel, the small-diameter section is disposed externally of the movable barrel, and both the connection of the large-diameter section and the small-diameter section urge against the first end cap;
- a second piston having one end plugged in the end of the large-diameter section of the first piston away from the small-diameter section, and an other end plugged in the second inner convex flange of the first cylinder adjacent to the second inner threaded portion;
- a second end cap including a second outer threaded portion rotatably and adjustably screwed with the second inner threaded portion of the first cylinder and urged against one end of the second piston adjacent to the second inner threaded portion;
- and
- an elastic member sleeved on the second piston and having two ends urged against the large-diameter section of the first piston and the first inner convex flange respectively;
- wherein the end of the movable barrel relative to the end having the outer convex ring is spaced apart or urged against the first inner convex flange so that it is configured to further adjust the position of one of the two flow-through holes while rotating the movable barrel through the outer convex ring.