Bi-directionally dynamically braked gate crossing mechanism controller
AssigneeWestern-Cullen-Hayes, Inc.
InventorsRodney L. Yourist, Robert W. Wardzala
Life of this patent
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Abstract
The output voltage of a D.C. motor used to raise and lower a railroad crossing 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 above 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.
Claims42
A railroad crossing gate control mechanism comprised of:
- a gate motor for raising and lowering a railroad gate, said gate motor having first and second motor terminals;
- a voltage or speed sensor having an input coupled to said motor terminals, said voltage or speed sensor detecting and being responsive to voltage levels present at said motor terminals indicative of when said gate motor acts as a generator, said voltage sensor having at least one output port and generating at said output port a first output signal if the voltage at said motor terminals is above a first threshold and generating a second output if the voltage at said motor terminals is above a second threshold;
- a gate motor speed limiter coupled to said output port of said voltage sensor and to said gate motor, said gate motor speed limiter dynamically braking said gate motor by coupling an impedance across said motor terminals.
A railroad crossing gate control mechanism comprised of:
- a gate motor for raising and lowering a railroad gate, said gate motor having first and second motor terminals;
- a motor speed or voltage sensor, said motor speed or voltage sensor detecting and being responsive to motor speed, said motor speed or voltage sensor detecting and being responsive to motor zero speed and said motor speed or voltage sensor detecting and being responsive to a series of predetermined power applied, power removed signals to said motor prior to removing supply power and dynamically braking said motor, said speed or voltage sensor generating an output signal if any of the aforementioned conditions are detected;
- and
- a gate motor speed limiter coupled to said output port of said motor speed sensor and to said gate motor, said gate motor speed limiter dynamically braking said gate motor by coupling an impedance across said motor terminals.
A mechanism for raising and lowering a railroad crossing gate arm, said mechanism comprising:
- a controller mechanism operatively connected to said railroad crossing gate arm for selectively raising and lowering said crossing gate arm;
- said controller mechanism having a bi-directionally operative gate arm controller for sensing when said gate arm is being raised at a rate of speed in excess of an adjustable predetermined rate of speed;
- said bi-directionally operative gate arm controller further sensing when said gate arm is being lowered at a rate of speed in excess of an adjustable predetermined rate of speed;
- and
- said controller mechanism having means for dynamically braking both said raising rate of speed and said lowering rate of speed of said gate arm when said gate arm controller senses either said excessive raising rate of speed or said excessive lowering rate of speed.
In a crossing gate control mechanism having a D.C. motor with an armature for raising and lowering a gate arm, a method of bi-directionally dynamically braking both the raising and lowering of said crossing gate arm by said gate control mechanism comprising the steps of:
- sensing the voltage of said armature of said D.C. motor when said gate arm is raising and when said gate arm is lowering;
- and
- when said voltage of said armature of said D.C. motor exceeds an adjustable predetermined threshold rate of speed when said gate arm is raising or lowering thereby indicating said D.C. motor is acting as a generator, then shunting said armature of said D.C. motor with an impedance to cause said D.C. motor to dynamically brake the rotation of said armature in both said raising and lowering directions of said gate arm, thereby dynamically braking the raising or lowering of said gate arm.
Dependencies are inferred from the claim text.