The present invention relates to a radially mounted disk brake used to brake a vehicle.
A known radially mounted disk brake includes a caliper having a plurality of mounting holes extending in a direction perpendicular to the axis of rotation of a disk rotor. The caliper is secured to a support member fixed to a vehicle body with mounting bolts passed through the mounting holes. In the radially mounted disk brake, when the caliper is secured to the support member on the vehicle body, tightening torque applied to the mounting bolts acts on a part of the caliper. This may cause the part of the caliper to be damaged. For the purpose of preventing such a problem, a conventional radially mounted disk brake adopts a structure in which sleeves are inserted into mounting holes provided in the caliper, and mounting bolts are inserted through the sleeves to secure the caliper to the support member on the vehicle body [see, for example, Japanese Patent Application Unexamined Publication (KOKAI) No. Hei 7-12148].
In the above-described conventional radially mounted disk brake, the flanges of the sleeves are sandwiched between the mutually opposing surfaces of the caliper and the support member on the vehicle body, and the abutting surfaces of the sleeves and the support members are plane surfaces. Therefore, it is likely that braking torque acting on the caliper during braking may cause the abutting surfaces to be relatively displaced in the axial direction of the disk rotor, and, consequently, the caliper may vibrate, causing brake judder.
If the tightening torque applied to the mounting bolts is simply increased to prevent the relative displacement of the abutting surfaces, the increased torque will cause the sleeves and the peripheries of the mounting holes of the caliper to be deformed radially outward of the mounting holes. If the deformation reaches a cylinder bore, the bore may be deformed. The deformation of the cylinder bore deteriorates the sliding performance of a piston sliding in the cylinder bore, resulting in impaired brake feeling.
Regarding the above-described deformation, a maximum amount of deformation occurs in the vicinity of the center of the axial length of a mounting hole. In a case where the center of the axial length of the mounting hole coincides with a thinnest-wall portion between the cylinder bore and the mounting hole, that is, a shortest-distance portion of the caliper at which the distance between the center of the cylinder bore and the mounting hole is shortest, the cylinder bore may be most deformed. Consequently, brake feeling will be further impaired.
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