Brake apparatus using light conductors to control remote wear indicators

Claim 1

A disk brake apparatus for a motor vehicle including a rotor connected to a wheel of said vehicle for rotation therewith, a non-rotatable brake shoe connected to the frame of said vehicle and disposed adjacent said rotor, means for moving said brake shoe axially toward said rotor to apply a braking force to said wheel, a friction pad having a flat friction surface subject to wear substantially parallel to said rotor and positioned for engagement therewith, and a plurality of rivets by which said pad is attached to said shoe, said rivets being recessed within said pad away from said friction surface to define a working thickness of said pad so that said rivets can contact said rotor only after said working thickness has been removed by wear, wherein the improvement comprises: a light source; at least one continuous elongated light conductor leading from said light sensor and having an intermediate sensor portion recessed within said friction pad and parallel to said rotor to define a severance level at which said rotor will contact and sever said sensor portion after a part of said working thickness has been worn away, said severance level being within said working thickness and closer to said rivets than to said friction surface, thereby defining a reserve thickness between said severance level and said rivets which permits continued wear of said pad beneath said severance level before said rivets contact said rotor; and display means connected to said light conductor at the end thereof opposite said light source for displaying, at a location remote from said pad and visible to the operator of said vehicle, an indication of the condition of said pad, said display means being responsive to the severance of said sensor portion to effect a change in said indication.