One-way and two-way brake auto-adjusters
A brake assembly has an auto-adjustment mechanism including an adjusting link that is rotatable to adjust an unloaded state position of a brake shoe, and an adjusting lever that operates to rotate the adjusting link during a release of the braking assembly to adjust the unloaded state position of the brake shoe. The auto-adjustment mechanism includes a pivot point mounted on a brake back plate about which the adjusting lever rotates, and an adjusting spring attached to the adjusting lever. The adjusting lever rotates in a first direction against the spring force when the brake assembly is actuated, and the adjusting spring by operation of the spring force rotates the adjusting lever in a second direction when the brake assembly is released. During the brake release, as the adjusting lever rotates back the adjusting lever catches the adjusting link in a ratchet fashion to rotate the adjusting link to adjust the unloaded state position of the brake shoes.
1. A brake assembly that transitions between an unloaded stated and a loaded state, wherein the brake assembly is actuated to transition from the unloaded state to the loaded state and is released to transition from the loaded state to the unloaded state, the brake assembly comprising:
a friction member;
a brake shoe that interacts against the friction member to apply a braking torque when the brake assembly is actuated; and
an auto-adjustment mechanism that automatically adjusts an unloaded state position of the brake shoe relative to the friction member;
the auto-adjustment mechanism comprising: an adjusting link that is rotatable to adjust the unloaded state position of the brake shoe, an adjusting lever that operates to rotate the adjusting link during a release of the braking assembly to adjust the unloaded state position of the brake shoe, an adjusting spring attached to the adjusting lever, and a pivot point about which the adjusting lever rotates in a first direction when the brake assembly is actuated and in a second direction opposite from the first direction when the brake assembly is released; and
the brake shoe comprising an end pad positioned at an end of the brake shoe and that contacts and drives a first end of the adjusting lever when the brake assembly is actuated to rotate the adjusting lever in the first direction against the spring force of the adjusting spring, and the adjusting spring by operation of the spring force rotates the adjusting lever in the second direction when the brake assembly is released.
2. The brake assembly of claim 1 , wherein:
the brake assembly includes a brake back plate and the pivot point is mounted to the brake back plate;
the adjusting spring is attached at a first end to the adjusting lever; and
the adjusting spring is attached at a second end opposite to the first end to a pin fixed to the brake back plate.
3. The brake assembly of claim 1 , wherein the adjusting lever has a first arm that is attached to the adjusting spring and a second arm that has a ratcheting end that operates to rotate the adjusting link.
4. The brake assembly of claim 3 , wherein the adjusting link has a plurality of teeth, and the ratcheting end of the adjusting lever catches a next one of the plurality of teeth during a release of the brake assembly to rotate the adjusting link.
5. The brake assembly of claim 4 , further comprising a connecting spring that spring mounts the brake shoe, wherein when the adjusting link rotates, teeth of the adjusting link interact with a coil portion of the connecting spring as the next one of the teeth rotates past the coil portion of the connecting spring to stretch the connecting spring to adjust the unloaded state position of the brake shoe.
6. The brake assembly of claim 5 , wherein:
the brake shoe has a brake pad that interacts against the friction member to apply the braking torque when the brake assembly is actuated;
when the brake assembly is actuated, the brake shoe moves over a stroke length, and the stroke length increases with wear of the brake pad; and
the stroke length increases based on wear of the brake pad until the adjusting lever rotates in an amount sufficient for the ratcheting end to overlap the next one of the plurality of teeth to rotate the adjusting link during a release of the braking assembly to adjust the unloaded state position of the brake shoe.
7. The brake assembly of claim 1 , wherein:
the brake shoe has a brake pad that interacts against the friction member to apply the braking torque when the brake assembly is actuated;
when the brake assembly is actuated, the brake shoe moves over a stroke length, and the stroke length increases with wear of the brake pad; and
the stroke length increases based on wear of the brake pad until the adjusting lever rotates in an amount sufficient to rotate the adjusting link during a release of the braking assembly to adjust the unloaded state position of the brake shoe.
8. The brake assembly of claim 1 , wherein the friction member is a cylindrical brake drum, and the brake shoe interacts against an inner surface of the brake drum to apply the braking torque.
9. The brake assembly of claim 1 , wherein the adjusting lever operates to rotate the adjusting link during a release of the braking assembly to adjust the unloaded state position of the brake shoe following actuation of the brake assembly in only one direction of brake loading.