TRAIN LENGTH MEASUREMENT SYSTEM

• US 3,641,338 A
• Filed: 02/26/1970
• Issued: 02/08/1972
• Est. Priority Date: 02/26/1970
• Status: Expired due to Term

• Current Assignee: Billie W. Phillips, Richard V. Peel
• Original Assignee: Billie W. Phillips, Richard V. Peel
• Inventors: Peel, Richard V., Phillips, Billie W.
• Primary Examiner(s): La Point, Arthur L.
• Assistant Examiner(s): Libman, George H.
• Application Number:
  US05/014,391
• Time in Patent Office: 712 Days
• Field of Search: 246/122R,1
• US Class Current: 246/1.00R
• CPC Class Codes: B61L 1/187 Use of alternating current

Abstract

A system for measuring the length of a train is disclosed and includes a transmitter for applying a current to an isolated area of a pair of railroad tracks. The area of the track is generally longer than the longest expected train. A fixed voltage is provided to the computer which is indicative of the distance from one end of the measurement area to the other. A detector is positioned at the furthest end of the track measurement area. As a train appears within the two points, the wheels from the train short out the tracks causing the received voltage therein to change. When the train is detected by the detector, a voltage reading is taken which is then indicative of the distance from the transmitter to the rear of the train. This distance voltage is then combined (subtracted) with the overall fixed voltage to supply a voltage which is indicative of the length of the train.

Claims

1. A train length measurement system for measuring the length of a train within a given area of tracks divided into a first section and a second section, said system including:

receiving means for receiving electrical indications from said tracks which are functions of the tracks electrical characteristics;

said means being adapted to provide indications from said first section or second sections;

a first detector being located at the end of the first track section, said first detector being adapted to indicate when a train has reached the end of the first section of track area;

a second detector being located at the end of the second track section of the track area, said second detector being adapted to indicate when a train has reached the end of the second section of the track area; and

means responsive to said first detector and said second detector for determining when a train is in the first section and the second section of said train area;

means for electrically isolating the track measurement area of said tracks from the remaining portion of said tracks;

a transmitter being coupled to the isolated track area and being adapted to electrically energize said isolated track area, said transmitter being disposed at one end of the first section of the isolated track measurement area furthest from said first detector; and

output means responsive to said receiving means and said first and second detectors for providing an output indication from said receiving means which is a function of the electrical characteristic of the first section when a train is in said first section and of the second section when a train is in said first and said second section.

2. The system as defined in claim 1 and further including means for applying a constant current to the tracks within the measurement area.

3. The system as defined in claim 1 wherein said output means including:

means coupled to said track for generating a first voltage indicative of the track input impedance;

means coupled to said track for generating a second voltage indicatIve of the reactance component of said track input impedance;

means for generating a third voltage proportional to the difference between said first voltage and said second voltage; and

means for combining said third voltage with said first voltage to provide a fourth voltage indicative of said distance.

4. The system as defined in claim 3 and wherein said means for generating said first voltage being an amplitude detector.

5. The system as defined in claim 3 and wherein said means for generating said second voltage being a quadrature detector.

6. The system as defined in claim 3 and wherein:

said means for generating said first voltage being an amplitude detector; and

said means for generating said second voltage being a quadrature detector.

7. The system as defined in claim 1 wherein said receiving means including:

a first receiver being coupled to the track area near one end of said first section and furthest from said first detector, and being adapted to receive electrical energy which is a function of the electrical characteristics of the first section of the tracks; and

a second receiver being coupled to the tracks near one end of said second section furthest from the second detector, and being adapted to receive electrical energy from the tracks which is a function of the electrical characteristics of the second section of the tracks.

8. A system for measuring the length of a train on a railroad train track including:

means coupled to said track for providing a total distance voltage which is indicative of the distance between a first point and a second point on said track, said distance being longer than the longest expected train to be measured;

means coupled to the first point of said track for providing a distance to train voltage which is indicative of the distance between the rear axle and wheels of the expected train and the first point on said track, and means for subtracting said distance to train voltage from said total distance voltage to provide a voltage indicative of the length of the train when the front of the train is located at the second point.

9. The system as defined in claim 8 and further including:

means coupled to said track and being located near the second point for detecting when said train reaches said second point.

10. The system as defined in claim 8 wherein said track located between said first point and said second point is insulated from the remainder of the track.

11. The system as defined in claim 8 and further including means for applying a voltage to said pair of tracks.

12. The system as defined in claim 8 wherein said means for providing a distance to train voltage including:

means coupled to said track for generating a first voltage indicative of the track input impedance;

means coupled to said track for generating a second voltage indicative of the reactance component of said track input impedance;

means for generating a third voltage proportional to the difference between said first voltage and said second voltage; and

means for combining said third voltage with said first voltage to provide a fourth voltage indicative of said distance.

13. The system as defined in claim 12 wherein said means for generating said first voltage being an amplitude detector.

14. The system as defined in claim 13 wherein said means for generating said second voltage being a quadrature detector.

15. The system as defined in claim 13 wherein:

said means for generating said first voltage being an amplitude detector; and

said means for generating said second voltage being a quadrature detector.

16. A train length measurement system for measuring the length of a train within an electrically isolated area of railroad tracks, said area of tracks being divided into a first section and a second section, said system including:

a transmitter being coupled to the isolated track area and being adapted to electrically eNergize said isolated area of tracks, said transmitter being located at one end of the first section of the track area;

a first receiver being coupled to the track area near said transmitter, said receiver being adapted to receive electrical energy from the tracks as a function of the track impedance;

a second receiver being coupled to the track area near the end of the first section furthest from said transmitter, said receiver being adapted to receive electrical energy from the track as a function of the track impedance;

a first detector being located at the end of the first track section furthest from said transmitter and near said second receiver, said first detector being adapted to indicate when a train has reached the end of the first section of the track area;

a second detector being located at the end of the second track section of the track area furthest from said transmitter and said second detector, said second detector being adapted to indicate when a train has reached the end of the second section of the track area;

logic switching means responsive to said first detector and said second detector for determining when a train is in the first section of the train area or in the first section and the second section of said train area; and

output means responsive to said first receiver and said second receiver, and said logic switching means for providing a train length measurement from said first receiver when a train is in the first section of the train area or from said second receiver when a train is in the first section and second section of the train area.