BI-DIRECTIONALLY DYNAMICALLY BRAKED GATE CROSSING MECHANISM CONTROLLER

摘要

The output voltage of a D.C. motor used to raise and lower a railroad crossi ng gate is monitored to detect when the D.C. motor begins to generate power, indicating that the motor is being driven by a rising gate arm. If the motor generates power abo ve a adjustable predetermined value, the gate arm mechanism is considered to be operating too fast whereupon an impedance is shunted across the motor's armature thereby applying a load to the generating motor. The electrical load causes the motor to act as a dynamic brake slowing the gate arm mechanism operation and reducing the likelihood that the mechanical components of the crossing gate arm mechanism will be damaged.