Disk brake apparatus

A disk brake apparatus comprising:

• a piston accommodated in the distal end opening side of a cylinder hole;
• a thrust conversion mechanism arranged on the bottom side of the cylinder hole;
• and
• an adjuster having an adjuster nut and an adjuster bolt, the adjuster being provided between the thrust conversion mechanism and the piston;
• wherein the piston is pushed by the thrust conversion mechanism through the adjuster;
• the thrust conversion mechanism comprises:
• a fixed side cam plate attached on the bottom wall of the cylinder hole;
• a camshaft passing through the cylinder hole bottom wall and the fixed side cam plate, the camshaft being rotatable with respect to the cylinder hole bottom wall and the fixed side cam plate and movable in the cylinder axis direction;
• a drive side cam plate provided at the cylinder hole opening side end portion of the camshaft;
• and
• ramp grooves formed in the drive side cam plate and the fixed side cam plate, each of the ramp grooves in the drive side cam plate and a corresponding one of the ramp grooves in the fixed side cam plate being arranged in positions facing each other;
• and
• cam bearings accommodated in the ramp grooves,
• wherein the adjuster comprises a thrust transmitting plate at the cylinder hole bottom side end portion, which faces the drive side cam plate of either one of the adjuster nut and the adjuster bolt;
• the thrust transmitting plate, the drive side cam plate, and a cam spring for biasing the thrust transmitting plate toward the drive side cam plate are accommodated in a generally cylindrical housing, the housing being mounted in the cylinder hole;
• engaging protrusions are formed on the outer circumference of the thrust transmitting plate;
• and
• a part of the arc face of the circumferential wall of the housing are deformed inwardly to form flat portions, and engaging apertures are formed on the flat portions, the engaging apertures being configured such that the engaging protrusions are movable only in the cylinder axis direction when the engaging apertures and the engaging protrusions are engaged.