Apparatus for detecting the presence and position of individual wheels or wheel-axles of railroad cars. The apparatus involves no moving parts and basically senses the presence of a car wheel by sensing a shunt current flowing through the car wheel-axle set. The apparatus or system includes a transmitter which develops a high frequency AC signal which is impressed across the rails, and a sense or pick-up coil which is sensitive to the fields produced by currents flowing up through the radius of the wheel, whereas it is substantially unaffected by fields produced by the currents flowing in the rails. A pair of current-carrying loops is provided, the first loop including a pair of rails and a pair of boundary shunts connecting said rails; the first loop being subdivided for current flow into two substantially equal portions with respect to a detection zone center line; the second loop extending in close proximity to and inside said first loop, said second loop likewise being subdivided for current flow.
展开▼
