The invention discloses a disk
hydraulic brake capable of adjusting automobile
brake clearance automatically. In the disk
hydraulic brake, an annular space for a sealing ring to move axially is reserved in a sealing ring groove. The cross sections of the space, the sealing ring and the sealing ring groove are approximately trapezoid or V-shaped or triangular; and the sealing ring is pressed by the
piston and the bottom of the sealing ring groove and performs static sealing basically. In braking, the
piston and the inner ring of the sealing ring are driven by an
oil pressure, the deformation resistance to axial movement of the inner ring of the sealing ring is overcome, a force for pulling back is stored, and a braking friction piece is linked to eliminate axial movement space and
brake clearance and press a braked part at the same time, and thus, friction
brake is realized. When braking is not needed, the
oil pressure is withdrawn, and under the action of the pull-back force of the sealing ring, the
machine parts and the two space clearances are restored. Thus, when braking is not needed, the
machine parts are protected from friction, heating, damage oil leakage and long repair and replace period, and are energy-saving, emission-reducing, low in consumption and safe. The structure of the disk
hydraulic brake is simple, and the production cost is unchanged basically.