Disc brake

A disc brake having a pair of pad plates installed to be movable forward and backward and a caliper housing which is slidably installed and provided with a cylinder allowing a piston to be installed therein to be movable forward and backward by hydraulic brake pressure, the disc brake comprising:

• an adjuster installed in the piston to prevent the pad plates from moving away from a disc and to maintain the pad plates a constant distance from the disc;
• a push rod installed in the cylinder, a front portion thereof being screw-coupled to the adjuster and a rear portion thereof being provided with a flange extending toward an inner circumferential surface of the cylinder;
• an element coupled to the flange to prevent rotation of the push rod and to move along with the push rod and seated in a seating groove provided at a rear wall of the cylinder;
• a spring case having an end of one side thereof fixed to the cylinder and forming a predetermined accommodation space between an inner circumferential surface of the cylinder and the push rod;
• and
• an elastic member arranged in the accommodation space of the spring case to provide elastic force to the push rod and the element, wherein the elastic member comprises:
• a low-pressure spring is arranged in the spring case, one end thereof being supported on a surface of the other side of the spring case and the other end thereof being supported by the flange to provide elastic force in a direction of movement of the piston;
• and
• a high-pressure spring is arranged in the spring case to be spaced a constant distance apart from the low-pressure spring, one end thereof being supported on the surface of the other side of the spring case and the other end thereof being supported by the element to provide elastic force in the direction of movement of the piston.