Electronic hot bearing detector

Claim 1

A HOT BEARING DETECTOR SYSTEM FOR RAILWAY ROLLING STOCK, COMPRISING NORMALLY DEACTIVATED ELECTRIC ALARM MEANS INCLUDING NORMALLY-OPEN RELAY CONTACTS; RELAY OPERATING MEANS FOR CLOSING SAID RELAY CONTACT TO ACTIVATE SAID ALARM MEANS, COMPRISING A VOLTAGE SOURCE, A RELAY COIL ENERGIZABLE TO CLOSE SAID RELAY CONTACTS, AND A NORMALLY NONCONDUCTIVE ELECTRONIC DEVICE HAVING A PAIR OF POWER CIRCUIT ELECTRODES CONNECTING SAID COIL IN SERIES WITH SAID SOURCE, SAID ELECTRONIC DEVICE INCLUDING ALSO A CONTROL ELECTRODE; MEANS APPLYING A DIRECT-CURRENT BIASING POTENTIAL OF ONE POLARITY UPON SAID CONTROL ELECTRODE FOR NORMALLY MAINTAINING SAID ELECTRONIC DEVICE NONCONDUCTIVE; AND TEMPERATURE-RESPONSIVE MEANS FOR APPLYING TO SAID CONTROL ELECTRODE AN AMPLIFIED SIGNAL VOLTAGE OF OPPOSITE POLARITY THAN SAID BIASING POTENTIAL AND OF A MAGNITUDE THAT IS A FUNCTION OF THE TEMPERATURE OF EACH WHEEL-AXLE JUNCTION OF THE ROLLING STOCK PASSING A GIVEN STATION, SAID TEMPERATURE RESPONSIVE MEANS COMPRISING STATIONARY PICK-UP MEANS INCLUDING A SINGLE HEAT RESPONSIVE CELL FOR GENERATING A SIGNAL VOLTAGE THAT IS A FUNCTION OF THE JOURNAL BEARING TEMPERATURE; MULTISTAGE AMPLIFIER MEANS INCLUDING AN INPUT STAGE AMPLIFYING DEVICE HAVING AN INPUT TERMINAL CONNECTED WITH SAID PICK-UP MEANS, AND AN OUTPUT STAGE AMPLIFYING DEVICE HAVING AN OUTPUT TERMINAL CONNECTED WITH SAID CONTROL ELECTRODE; AND MULTIVIBRATOR GATING MEANS FOR ALTERNATELY RENDERING SAID INPUT STAGE AMPLIFYING DEVICE CONDUCTIVE AND NONCONDUCTIVE, SAID AMPLIFIER MEANS INCLUDING ALSO SIGNAL CLIPPING MEANS CONNECTING BETWEEN SAID INPUT AND OUTPUT STAGE AMPLIFYING DEVICES FOR ELIMINATING THE EFFECT OF SAID MULTIVIBRATOR GATING MEANS AND FOR PRODUCING AT THE OUTPUT TERMINAL OF SAID OUTPUT STAGE AMPLIFYING DEVICE AN AMPLIFIED SIGNAL VOLTAGE THE MAGNITUDE OF WHICH IS A DIRECT FUNCTION OF THE WHEEL-AXLE JUNCTION TEMPERATURE, WHEREBY WHEN THE WHEEL-AXLE TEMPERATURE EXCEEDS A GIVEN VALUE, SAID AMPLIFIED SIGNAL VOLTAGE EXCEEDS SAID BIASING POTENTIAL AND SAID RELAY DRIVING DEVICE IS RENDERED CONDUCTIVE TO ACTIVATE SAID ALARM MEANS.