Patent ID: 8668058

Claim:
A ventilated brake disc rotor for a vehicle braking system, said rotor comprising: an annular inboard friction plate having a central axis; an annular outboard friction plate spaced from said inboard friction plate and concentrically disposed about said central axis; a plurality of ribs disposed between said inboard and outboard friction plates, said ribs spaced one from another in regular circumferential increments about said central axis with a generally radially extending vent hole defined in the space between adjacent ribs; said plurality of ribs being arranged in four arcuate sectors of equal angular measure, each of said sectors containing an attenuation region in which the regular spacing of said ribs is interrupted, each said attenuation region occupying at least 20% but not more than 55% of the surface area represented by the respective said sector; a pin cluster disposed in each said attenuation region, each said pin cluster including at least two distinct rows of radially aligned pins; said pins disposed in-between and interconnecting said inboard and outboard friction plates, said pins in each said pin cluster being at least six in number and spaced both radially and circumferentially from one another; and said at least two rows of pins in each said pin cluster containing an equal number of pins, each said row including a radially innermost pin, a radially intermediate pin and a radially outermost pin; the circumference of each radially intermediate pin being greater than the circumference of each radially innermost pin, and the circumference of each radially outermost pin being greater than the circumference of each radially intermediate pin.