Automatic adjusting means for internal shoe drum brakes

Claim 2

Automatic brake-adjusting means for a brake comprising a pair of spaced brakeshoe members, a fluid pressure bRake-expanding means, a separate and independent mechanical brake-expanding means comprising a strut engaged at one end with one brakeshoe member, a lever pivoted on the strut and engaging the other brakeshoe member, length-adjusting means including a ratchet wheel on said strut to increase the overall length of said strut, pawl means on said lever to engage said ratchet wheel to rotate it and lengthen said strut, said wheel being movable idly by said pawl means upon a first brake application by said fluid pressure brake-expanding means and by a first application of said mechanical brake-expanding means and by a first application of said mechanical brake-expanding means, and a spring operatively connected to said pawl means and a brakeshoe member to rotate said ratchet wheel in a drive direction opposite to said idle movement direction when said fluid pressure brake-expanding means is again applied.

Claim 3

Automatic-adjusting means for an internal shoe drum brake in which both fluid pressure means and mechanical means are provided for expanding the shoes into engagement with the drum, wherein the mechanical shoe-expanding means constitute an adjustable shoe spacing assembly supporting the shoes against inward movement by pulloff springs, and one-way driving means, acting on length-increasing means embodied in the said spacing assembly which are moved in the nondriving direction by actuation of the mechanical shoe-expanding means to expand the shoes and are moved in the driving direction by a spring when the shoes are expanded by the fluid pressure means and the spacing assembly is thereby relieved of the load exerted on the shoes by the pulloff springs, said mechanical shoe-expanding means comprising a strut engaging at one end with one shoe, a lever pivoted on the strut and engaging the other shoe, stop means to limit angular movement of the lever in one direction relative to the strut to limit inward movement of the shoes relative to each other under the load of the pulloff spring means, means controlled by angular movement of the lever relative to the strut to increase the length of the strut, including a ratchet wheel, the rotation of which actuates means to vary the length of the strut, a pawl movable idly relative to the ratchet wheel by movement of the lever relative to the strut and a spring, loaded by such movement of the pawl, acting in the pawl in a direction to move the ratchet wheel and means actuated thereby to increase the length of the strut, said pawl being pivotally mounted on said strut and being provided with a tail portion cooperating with a lateral projection on the lever.

Claim 4

Automatic-adjusting means for an internal shoe drum brake in which both fluid pressure means and mechanical means are provided for expanding the shoes into engagement with the drum, wherein the mechanical shoe-expanding means constitute an adjustable shoe spacing assembly supporting the shoes against inward movement by pulloff springs, and one-way driving means, acting on length-increasing means embodied in the said spacing assembly which are moved in the nondriving direction by actuation of the mechanical shoe-expanding means to expand the shoes and are moved in the driving direction by a spring when the shoes are expanded by the fluid pressure means and the spacing assembly is thereby relieved of the load exerted on the shoes by the pulloff springs, said mechanical shoe-expanding means comprising a strut engaging at one end with one shoe, a lever pivoted on the strut and engaging the other shoe, stop means to limit angular movement of the lever in one direction relative to the strut to limit inward movement of the shoes relative to each other under the load of the pulloff spring means, means controlled by angular movement of the lever relative to the strut to increase the length of the strut, including a ratchet wheel, the rotation of which actuates means to vary the length of the strut, a pawl movable idly relative to the ratchet wheel by movement of the lever relative to the strut and a spring, loaded by such movement of the pawl, acting in the pawl in a direction to move the ratchet wheel and means actuated thereby to increase the length of the strut, said pawl being pivotally mounted on said strut and being provided with a tail portion cooperating with a lateral projection on the lever.

Claim 5

Automatic adjusting means of claim 2 wherein said stop means to limit angular movement of the lever comprises a washer mounted on a pivot pin providing the pivotal mounting for said pawl.