Method and apparatus for detecting railroad cars

Apparatus for identifying individual railroad cars among a train of railroad cars arranged on a track, wherein each car has two weight-bearing wheel trucks disposed beneath and at opposite ends thereof, each of said trucks having at least two axles arranged adjacent to each other such that the maximum distance between the axles of a single truck is less than the center distance between facing axles of the two trucks of a respective car, said apparatus comprising, in combination:

• (a) means for measuring the distance between successive axles as a train of cars moves in one direction along the track;
• (b) means, coupled to said distance measuring means, for comparing each measured distance with the maximum axle distance for a truck;
• and
• (c) means, coupled to said comparison means, for determining whether the axle spacing of a first truck equals the axle spacing of a second truck after the maximum axle distance for a truck has been exceeded;
• whereby an individual car is identified upon identification of two identical truck assemblies which are separated by an axle spacing that is greater than said maximum axle distance.