US 4,546,295 AGranted

Electric actuators

AssigneeWestinghouse Brake & Signal Co. Ltd.

InventorsDavid J. Wickham, Jack Washbourn, Howard F. Cogan

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Abstract

The present invention provides an electric actuator having an output member movable from a first variable position to a second variable position; an electric motor operable to control a spring system to exert an output force on the output member when in its second position; a device for generating an electrical signal when the output member is about to leave the second position as it returns to the first position; and a motor-control electrical circuit which recognizes the generation of the electrical signal and thereafter operates the electric motor to a pre-determined degree to move the output member a corresponding pre-determined distance back to the first position so that there is preserved a substantially constant distance between the first and second positions.

Claims8

Dependent claims

An electric actuator having an output member movable from a first variable position to a second variable position;

a spring means for exerting a variable output force on said output member for transmission thereby, when said output member is in the second position thereof;
an electric motor means for controlling said spring means to control the variable output force exerted on the output member when the output member is in second position thereof;
means for generating an electrical signal when the output member is about to leave the second position for return thereof to the first position;
and motor-control electrical circuit means, responsive to the generation of the electrical signal, for controlling the operation of the electric motor so as to cause the output member to move a predetermined distance back to the first position which maintains a substantially constant spacing between the first and second positions.

1 more element

Dependencies are inferred from the claim text.