Patent ID: 7793764

Claim:
A wet brake system for a vehicle comprising: a case; an internal operation lever; a hydraulic cylinder which is integrally mounted to the case and is configured to actuate the internal operation lever; and a brake mechanism configured to be operated by the actuation of the internal operation lever by the hydraulic cylinder to apply a braking force to an axle of the vehicle; wherein the brake mechanism includes a cam plate which is rotatable to cause the brake mechanism to generate the braking force, and the cam plate has a protruding portion protruding circumferentially; wherein the internal operation lever includes a rotational shaft, a driving protrusion protruding radially from the rotational shaft, and a driven protrusion protruding radially from the rotational shaft; wherein the hydraulic cylinder includes a cylinder case forming a cylinder portion, a piston portion which is axially movable inside the cylinder by an action of an oil pressure, and an operating portion coupled to an axial end surface of the piston portion; wherein a base end portion of the operating portion is coupled to the axial end surface of the piston portion to make a curved-surface contact between them to cause the operating portion to tilt axially by the action of the oil pressure via the piston portion, a tip end portion of the operating portion is coupled to the driven protrusion of the internal operation lever by a ball joint, and the driving protrusion of the internal operation lever is coupled to the protruding portion of the cam plate to make a curved-surface contact between them; and wherein the operating portion of the hydraulic cylinder protrudes into the case, and the driving protrusion and the driven protrusion of the internal operation lever are disposed in the case.