Self-adjusting brake

In a brake construction of the type including a brake band substantially encircling a brake drum mounted on a support for rotation about a fixed axis, the brake band having first and second spaced ends connected to a control linkage selectively operable between a normal released condition, towards which the linkage is biased and wherein the brake band ends are positioned such that the band is spaced from said drum, and a brake-applying condition, wherein the brake band ends are positioned closer together than when in their released positions and the band is in engagement with said drum, said control linkage having first and second anchor pins respectively connected to the first and second ends of the brake band and extending parallel to said axis, said support having means guidingly retaining said first and second anchor pins for limited movement towards and away from each other, a lever having said second anchor pin mounted therein, a third anchor pin mounted in said lever, said support including surface means defining a seat-shaped complementary to and disposed so as to receive said third anchor pin when the linkage is in said released condition, a motion-transmitting link connected between said first and third anchor pins and including rotatable ratchet wheel means operable for adjusting the released position of said first anchor pin so as to compensate for brake band wear, wherein the improvement comprises:

• an adjusting means for indexing said ratchet wheel means;
• a control linkage actuating means for causing said control linkage to assume a released condition or a brake applied condition, said adjusting means being connected between said ratchet wheel means and control linkage actuating means and operable in response to a predetermined movement of said actuating means to a brake applied condition to index said ratchet wheel means upon the linkage returning to said released condition, said control linkage actuating means including:
• a hydraulic cylinder having a cylinder arm linearly movable;
• a connecting link pivotally mounted to said lever at one end;
• a second motion transmitting link pivotally mounted to said cylinder arm at one end and pivotally mounted to the housing at the other end, said connecting link being pivotally mounted along said second motion transmitting link such that movement of said cylinder arm causes said lever to rotate about said second or third pins.