Magnetic object detection

A magnetic object detection and direction sensing system comprising:

• first and second variable permeability magnetic object detection devices each including:
• an electromagnetic sensing coil;
• a core disposed in said electromagnetic sensing coil and having a first permeability when said core is magnetically saturated and a second, different permeability when said core is magnetically unsaturated;
• a magnet member proximate said electromagnetic sensing coil for providing a magnetic field in said core for operating said core in a magnetically saturated state without a magnetic object to be detected present in the area proximate said electromagnetic sensing coil, interacting with said magnetic field, and for operating said core in a magnetically unsaturated state with a magnetic object to be detected present in the area proximate said electromagnetic sensing coil, interacting with said magnetic field;
• and
• means, responsive to said electromagnetic sensing coil, to detect the presence of a magnetic object;
• and
• a direction sensing device, responsive to each of said means to detect the presence of a magnetic object, for determining whether said first detection device or said second detection device first detected a magnetic object.

A wheel detector for detecting the magnetic mass of a railroad car wheel comprising:

• a housing for mounting on the rail of railroad racks;
• a variable permeability magnetic detection device carried by said housing and including:
• an electromagnetic sensing coil;
• a core disposed in aid electromagnetic sensing coil and having a first permeability when said core is magnetically saturated and a second, different, permeability when said core is magnetically unsaturated;
• a magnetic member proximate said electromagnetic sensing coil for providing a magnetic field in said core for operating said core in a magnetically saturated state without a magnetic object to be detected present in the area proximate said electromagnetic coil, interacting with said magnetic field, and for operating said core in a magnetically unsaturated state with a magnetic object to be detected present in the area proximate said electromagnetic sensing coil, interacting with said magnetic field;
• and
• means, responsive to sid electromagnetic sensing coil, to detect the presence of a magnetic object.

A wheel detector for detecting the magnetic mass of a passing railroad car wheel and its sense of direction comprising:

• a housing for mounting on the rail of a railroad track;
• first and second variable permeability magnetic detection devices mounted in said housing each including:
• an electromagnetic sensing coil;
• a core disposed in said electromagnetic sensing coil and having a first permeability when said core is magnetically saturated and a second, different permeability when said core is magnetically unsaturated;
• a magnetic member proximate said electromagnetic sensing coil for providing a magnetic field in said core for operating said core in a magnetically saturated state without a magnetic object to be detected present in the area proximate said electromagnetic sensing coil, interacting with said magnetic field, and for operating said core in a magnetically unsaturated state with a magnetic object to be detected present in the area proximate said electromagnetic sensing coil, interacting with said magnetic field;
• and
• means, responsive to said electromagnetic sensing coil, to detect the presence of a magnetic object;
• and
• a direction sensing device, responsive to each of said means to detect the presence of a magnetic object, for determining whether said first detection device or said second detection device first detected a magnetic object.