Disk brake

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

• an adjuster installed inside the piston to prevent the pad plates from withdrawing from a disc and maintain the pad plates at a distance from the disc;
• a pull-rod installed in the cylinder, a front portion thereof being screwed to the adjuster and a rear portion thereof being provided with a flange extending toward an inner circumferential surface of the cylinder;
• a support member coupled with a rear wall of the cylinder to support the pull-rod and seal an inside of the cylinder;
• a spring case adapted to have one end fixed to the support member and form a predetermined accommodating space;
• and
• an elastic member arranged in the accommodating space of the spring case to return the piston to an original position thereof,
• wherein the elastic member comprises:
• a low-pressure spring arranged in the spring case, with one end thereof supported on an inner side surface of the spring case and the other end thereof supported by the flange to provide elastic force in a direction of movement of the piston;
• and
• a high-pressure spring arranged in the spring case to be spaced a distance from the low-pressure spring, with one end thereof supported on the inner side surface of the spring case and the other end thereof supported by the support member to provide elastic force in the direction of movement of the piston.