Electromagnetically operated friction brake having automatic adjustment mechanism
AssigneeTorvale Transmissions Limited
InventorDavid J. Webb
Life of this patent
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Abstract
A brake comprises a base on which a pair of brake shoes are mounted, springs to resiliently bias the brake shoes into engagement with a drum which is fixed relative to a rotatable member to be braked, to apply the brake, an electromagnet to move the brake shoes against the springs to release the brake, the electromagnet comprising a coil and an armature movable relative to the coil when the coil is energized, and a lost motion device automatically to maintain the movement of the armature relative to the coil within a predetermined range of movement irrespective of the amount of wear of the brake shoes.
Claims14
A brake comprising a base, a pair of brake shoes, means mounting the brake shoes on the base, a drum to be braked, means resiliently to bias the brake shoes into engagement with the drum to apply the brake, electromagnetic means to move the brake shoes against the resilient biasing means to release the brake, the electromagnetic means comprising an electromagnet having a coil and an armature movable relative to the coil when the coil is energised, the resilient biasing means biasing the armature of the electromagnet into engagement with one of the shoes whilst a housing of the coil of the electromagnet is resiliently biased in an opposite direction by the resilient biasing means, a connecting element connecting the housing and the other of the brake shoes so that the shoes are both oppositely biased into engagement with the drum, and means automatically to maintain the movement of the armature relative to the coil within a predetermined range of movement irrespective of the amount of wear of the brake shoes, the maintaining means comprising a lost motion mechanism having a one way clutch mounted adjacent to the electromagnet and operated by a linkage means that is mounted to be pivotable on the housing of the coil and on the armature and automatically varying the effective length of the connecting element by an amount corresponding to the amount of wear of the brake shoes.
A brake comprising a base, a pair of brake shoes, means mounting the brake shoes on the base, a drum to be braked, means resiliently to bias the brake shoes into engagement with the drum to apply the brake, electromagnetic means to move the brake shoes against the resilient biasing means to release the brake, the electromagnetic means comprising an electromagnet having a coil and an armature movable relative to the coil when the coil is energised, the resilient biasing means biasing the armature of the electromagnet into engagement with one of the shoes whilst a housing of the coil of the electromagnet is resiliently biased in an opposite direction by the resilient biasing means, a connecting element connecting the housing and the other of the brake shoes so that the shoes are both oppositely biased into engagement with the drum, and means automatically to maintain the movement of the armature relative to the coil within a predetermined range of movement irrespective of the amount of wear of the brake shoes, the maintaining means comprising lost motion means having a one way clutch mounted adjacent to the electromagnet and operated by a linkage means that is mounted to be pivotable on the housing of the coil and on the armature and automatically varying the effective length of the connecting element by an amount corresponding to the amount of wear of the brake shoes, the linkage means of the lost motion means comprising a first link member pivotally connected at one end to the armature and at the other end to a second link member which itself is pivotally secured to the housing at the coil of the electromagnet, the second link member being rigid with a lever which when rotated at least in one sense of the rotation causes the effective length of the connecting element to be reduced.
Dependencies are inferred from the claim text.