Switch machine controller with fail safe mechanism

Abstract

A switch machine controller for providing fail safe control of a switch machine, having a motor for actuating the movements of a railroad switch, said motor being a brushless D.C. motor having a permanent magnet structure and a plurality of independent field coils. The controller has control circuitry for energizing and de-energizing field coils of said motor sequentially as the armature rotates. Further the controller, including a motor driver arrangement for switching a first service of power sequentially to said field coil of said motor, switches machine control lines connected to second source of power. Also, an amplifier for controlling timing signals which, in turn, controls the motor driver, thus receiving its power only from said switch machine control lines, and can only generate the proper sequence of signals when the control lines are energized, such that the motor can only run when the control lines are energized.

Dependencies are inferred from the claim text.