Electromagnetic track apparatus, particularly for axle-counting systems in railway safety installations

Claim 1

ELECTROMAGNETIC TRACK APPARATUS FOR RAILROAD-CAR AXLE-COUNTING SYSTEMS COMPRISING A TRANSMITTING COIL POSITIONED ON ONE SIDE OF ONE OF THE RAILS OF THE TRACK, A RECEIVING COIL POSITIONED ON THE OTHER SIDE OF SAID RAIL, SAID TRANSMITTING COIL BEING ADAPTED TO GENERATE AN ALTERNATING MAGNETIC FIELD, WHEREBY A VOLTAGE IS INDUCED IN SAID RECEIVING COIL THE MAGNITUDE OF WHICH IS ALTERED BY THE PRESENCE OF A RAILROAD CAR WHEEL IN THE REGION OF SAID FIELD, MEANS FOR MOUNTING SAID RECEIVING COIL SO AS TO FORM A MAGNETIC BRIDGE, SAID MEANS COMPRISING A LOW RELUCTANCE ARM EXTENDING AT A RIGHT ANGLE FREE FROM THE LOWER PART OF THE CORE OF WHICH IT IS AN INTEGRAL PART AND ATTACHED TO SAID RAIL AT A POINT BETWEEN THE RAIL HEAD AND THE RAIL FOOT, A HOUSE OF MAGNETICALLY NONCONDUCTIVE MATERIAL SURROUNDING SAID MOUNTING MEANS AND SAID RECEIVING COIL SO THAT THE FLUX LINES OF SAID FIELD FOLLOW PREDETERMINED PATHS IN SAID MAGNETIC BRIDGE, AND ADJUSTABLE MEANS FOR MOUNTING SAID TRANSMITTING COIL AT SUCH AN ANGLE WITH RESPECT TO SAID RAIL THAT THE PRESENCE OF A FLANGE OF A RAILROAD CAR WHEEL IN THE GAP BETWEEN SAID RAIL HEAD AND SAID RECEIVING COIL WILL ALTER THE ALTERNATING MAGNETIC FIELD ACTING UPON SAID RECEIVING COIL.