Method for hot box detection

Claim 1

A HOT BOX DETECTING SYSTEM COMPRISING A PAIR OF HEAT SENSOR MEANS ADAPTED TO BE MOUNTED ON OPPOSITE SIDES OF A RAILROAD TRACK AND FURTHER ADAPTED TO PRODUCE FIRST AND SECOND ELECTRICAL SIGNALS IN RESPONSE TO INCIDENT RADIANT ENERGY EMITTED BY PASSING JOURNAL BOXES, ELECTRICAL DIFFERENCE-DETERMINING MEANS COUPLED TO SAID FIRST AND SECOND SIGNALS TO PROVIDE A THIRD SIGNAL COMMENSURATE WITH THE DIFFERENCE IN MAGNITUDE BETWEEN SAID FIRST AND SECOND SIGNALS, ELECTRICAL ADDING MEANS COUPLED TO SAID FIRST AND SECOND SIGNALS TO PROVIDE A FOURTH SIGNAL COMMENSURATE WITH THE SUM OF SAID FIRST AND SECOND SIGNALS, ELECTRICAL RATIO FORMING MEANS RESPONSIVE TO SAID THIRD AND FOURTH SIGNALS AND OPERATIVE TO PROVIDE A FIFTH SIGNAL COMMENSURATE WITH THE RATIO BETWEEN SAID THIRD AND FOURTH SIGNALS, AND MEANS RESPONSIVE TO SAID FIFTH SIGNAL TO PROVIDE AN OUTPUT INDICATION WHENEVER THE MAGNITUDE OF SAID FIFTH SIGNAL EXCEEDS A PREDETERMINED THRESHOLD MAGNITUDE.