Self-adjusting drum type brake

Claim 2

In an automatic adjusting mechanism for a drum-type brake having a shoe with a frictional lining and a web, an extensible mechanism for determining the at rest position of the shoe and an adjusting lever pivotally movable in response to a predetermined amount of movement of the shoe for adjusting the extensible mechanism, the improvement comprising a supporting lever supported upon the web of the shoe for pivotal movement about a first pivot axis, means supporting said adjusting lever upon said supporting lever for pivotal movement about a second pivot axis, said adjusting lever being movable about said second pivot axis for operation of the extensible mechanism, said supporting lever being pivotal about said first axis when said adjusting lever pivots about said second axis and when said extensible mechanism cannot be extended for precluding damage to said automatic adjusting mechanism.

Claim 3

An automatic adjusting mechanism as set forth in claim 1 further including means for biasing the supporting lever for rotation about the first pivot axis in a first direction, said biasing means being yieldable for movement of said supporting lever about said first pivot axis in a direction opposite to said first pivot axis.

Claim 4

An automatic adjusting mechanism as set forth in claim 2 further including stop means on the supporting lever engageable with means on the shoe for determining the first position of said supporting lever.

Claim 5

An automatic adjusting mechanism as set forth in claim 1 further including hold down means for holding the adjusting lever in position relative to the backing plate and for holding the brake shoe in position relative to the backing plate, the hold down means including a spring retainer which forms the second pivotal axis.

Claim 6

An automatic adjusting mechanism as set forth in claim 4 further including spring means biasing the supporting lever for rotation in a first direction about the first pivot axis, said supporting lever having stop means thereon engageable with the brake shoe for determining a normal position for said supporting lever.

Claim 7

A drum type brake comprising a brake shoe having a web, an extensible mechanism in engagement with one end of said web for determining the at rest position of said brake shoe, actuating means disposed in engagement with the other end of said web for urging said brake shoe into engagement with an associated drum, said extensible means including a star wheel, an adjusting lever having an end portion adapted to engage said star wheel, a supporting lever pivotally supported upon said web, means for pivotally supporting said adjusting lever upon said supporting lever, an adjusting means operatively connected to said adjusting lever and to a fixed element of said brake for pivoting said adjusting lever about said second pivot axis for rotating said star wheel upon a predetermined degree of wear of the lining of said brake shoe, said supporting lever being pivotal about said first pivot axis when said star wheel cannot be rotated.

Claim 8

A drum type brake comprising a brake shoe having a web, an extensible mechanism in engagement with one end of said web for determining the at rest position of said brake shoe, actuating means disposed in engagement with the other end of said web for urging said brake shoe into engagement with an associated drum, said extensible means including a star wheel, an adjusting lever having an end portion adapted to engage said star wheel, a supporting lever pivotally supported upon said web, means for pivotally supporting said adjusting lever upon said supporting lever, an adjusting means operatively connected to said adjusting lever and to a fixed element of said brake for pivoting said adjusting lever about said second pivot axis for rotating said star wheel upon a predetermined degree of wear of the lining of said brake shoe, said supporting lever being pivotal about said first pivot axis when said star wheel cannot be rotated.