US 5,057,728 AGranted

Three step electric brake

AssigneeCrown Equipment Corporation

InventorsNed E. Dammeyer, Nicholas J. Sherman, Nicholas D. Thobe

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Abstract

A variable braking force electric brake for materials handling vehicles, such as fork lift trucks, utilizes two sets of springs to urge brake pads against a rotor of a disc brake. The first set of springs provide a first level of braking force, typically one-third of the total braking force. The second set of springs provide a second level of braking force, typically two-thirds of the total. A pair of electromagnetic elements act on armatures placed between the springs and a non-magnetic brake pad support plate to selectively permit either the first set of springs alone to provide braking, the second set of springs alone, or both sets together. Initially, the current to the electromagnetic elements is strong, to insure that the associated armature is pulled toward the electromagnet, and afterwards, the current is reduced to minimize heating and power requirements. The space or gap between the electromagnets and the armatures may be ascertained by means of a feeler gauge, or be examining a plunger, the end of which extends through the outer housing of the brake. The gap is determined by a set of three adjusting screws placed around the periphery of the brake housing.

Claims8

Dependent claims

In a variable braking force electric brake including

a rotating shaft,
a brake rotor mounted for rotation with the shaft,
a housing fixed against rotation,
brake pads associated with said housing and positioned on opposite sides of said rotor for engaging and stopping the rotation of said rotor when applied thereto, and
means for urging said pads against said rotor,
the improvement comprising
first and second brake pad support elements, said first brake pad support element located on one side of said rotor and said second brake pad support element located on the other side of said rotor,
an inner armature cooperating with said second brake pad support element,
a first plurality of springs placed between said housing and said inner armature for applying a first level of force against said rotor,
an outer armature cooperating with said second brake pad support element and spaced radially outwardly of said inner armature,
a second plurality of springs placed between said housing and said outer armature for applying a second level of force against said rotor,
first and second electromagnetic means mounted to said housing for interacting with said inner and outer armatures, respectively, to move said pads away from said rotor against the force of said springs, and
means for selectively actuating said first and second electromagnetic means for providing a first level of braking force when said first electromagnetic means is released, a second level of braking force when said second electromagnetic means is released, and a third level of braking force when both said electromagnetic means are released, and wherein no braking force is applied when both said electromagnetic means are energized.

10 more elements

A variable braking force electric brake for attachment to a rotating shaft,

said brake including a brake rotor supported for rotation with the shaft, a housing fixed against rotation, brake pads associated with said housing and positioned on opposite sides of said rotor for engaging and stopping the rotation of said rotor when applied thereto, means for urging said pads against said rotor, and means for controlling said brake,
wherein said urging means includes inner and outer armatures cooperating with said brake pad support elements,
a first plurality of springs placed between said housing and said inner armature for applying a first level of force against said rotor,
a second plurality of springs placed between said housing and said outer armature for applying a second level of force against said rotor,
and wherein said means for controlling said brake includes first and second electromagnetic means mounted to said housing for interacting with said inner and outer armatures, respectively, to move said pads away from said rotor against the force of said springs, and
means for selectively actuating said first and second electromagnetic means for providing a first level of braking force when said first electromagnetic means is released, a second level of braking force when said second electromagnetic means is released, and a third level of braking force when both said electromagnetic means are released, and wherein no braking force is applied when both said electromagnetic means are energized.

3 more elements

Dependencies are inferred from the claim text.