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.