Apparatus to sense and annunciate truck brake condition

In a braking system having opposed brake shoe arms pivotally movable into frictional engagement with the circumferential rim of a brake drum by means of an "S" cam carried for rotation on an "S" cam shaft having an end extending externally of the brake drum and activated by a radially extending adjustment arm having a clevis interconnecting driving linkage spacedly adjacent the "S" cam shaft, apparatus to sense and annunciate brake condition at a distance from the brake system, comprising in combination:

• a cam shaft disk having an elongate sleeve-like sensor body with first and second ends defining a channel for carriage upon the splined end of the "S" cam shaft, said body defining a disk bearing surface and having clamping weans at the first end to releasably positionally maintain at least a first end portion of the body upon an "S" cam shaft, said body carrying an annular cam shaft disk at the second end, said cam shaft disk carrying a first switching means radially spaced from its bore;
• an annular sensor disk journaled on the sleeve-like body of the cam shaft disk adjacent the cam shaft disk, said sensor disk carrying second and third switching means, respectively, on each side, said second switching means operatively communicating with the first switching means carried by the cam shaft disk, said sensor disk having adjustable mechanical linkage to maintain the sensor disk in fixed rotary position relative to the sleeve-like body carrying it;
• an annular slack adjuster arm disk rotatably carried by the sleeve-like body of the cam shaft measuring disk adjacent the sensing disk and spacedly distant from the cam shaft disk, said slack adjuster arm disk having, forth switching, means in the surface adjacent the sensor disk to operatively communicate with the third switching means on the adjacent surface of the sensor disk, said slack adjuster arm disk having an adjustably positionable adjustment arm extending radially to communicate with an outer end portion of the slack adjuster arm to cause the slack adjuster arm disk to rotate responsively to the motion of the slack adjustment arm;
• and
• an annunciating system having at least two annunciators at a spaced distance from the brake system, a first annunciator communicating with the third switching means to annunciate the proximity of the fourth switching means carried by the slack adjuster arm disk with the third switching means proximate thereto to indicate need for brake slack adjustment and a second annunciator to annunciate proximity of the first switching means carried by the cam shaft disk to the second switching means to indicate parts wear.