GB969348A - Improvements in and relating to heat source detection systems - Google Patents

Abstract

969,348. Detecting overheated wheel journals. GENERAL SIGNAL CORPORATION. Sept. 11, 1961 [Sept 19, 1960]. No. 32499/61. Heading B7N. In a system for detecting overheated journals on rail vehicles, means are provided for determining whether the overheated condition is due to the journal or to dragging brakes. The arrangement includes infra-red radiation detectors RD1, RD2 positioned on opposite sides of the track and arranged to scan each passing wheel along a line parallel to the track and passing through the hub, a magnetic wheel detector WD1 positioned on a line passing through the radiation detectors and similar wheel detectors WD2, WD3 positioned approximately 10 inches to either side of detector WD1. Output pulses are produced by circuit 15 when a wheel passes over detector WD1 and by circuit 25 when a wheel passes over either detector WD2 or WD3. The pulse from circuit 15 triggers a monostable flip-flop 16, which produces an output pulse of short duration, and also triggers a bi-stable flip-flop 17 which is returned to its initial condition by the pulse from circuit 25. The output from flip-flop 16 triggers a second mono-stable flip-flop 19 which produces an output pulse for a predetermined time after flip-flop 16 has returned to its initial condition. The output from the detectors, e.g. RD1, is applied via a preamplifier 21 and amplifier 22 to a hub signal storage circuit 20 and to a hub and web signal comparing circuit 23. In the signal storage circuit 20 the amplified signal is passed to ground except during the period when a gating pulse from flip-flop 16 is present and during this period the signal is stored if its amplitude exceeds a predetermined value. With the arrival of a gating pulse from flip-flop 19 the signal is applied to an analogue recording pen AP No.1 and also to the hub and web signal comparing circuit 23. If the signal does not exceed the predetermined value the arrival of the gating pulse from circuit 19 generates a small signal which is recorded by the analogue pen to indicate the passage of a train wheel. In the comparison circuit 23, in the presence of a gating signal from flip-flop 17 the hub signal is stored and compared with the output of amplifier 22 which is now indicative of the web temperature. If the hub temperature signal exceeds the web temperature signal an output is supplied to marker pen MP No. 1. The analogue and marker pens record on the same graph and each analogue marking indicates, depending on its amplitude, a passing wheel with a normal or overheated journal. An overheated journal signal in the absence of a corresponding marker signal indicates a dragging brake. The output from flip-flop 17 also acts in a circuit 18 to operate a relay R during the period a train is passing through the test location. The relay opens a shutter which protects the infra-red detector in each unit in the absence of a train and additionally switches on the recorder. Reference has been directed by the Comptroller to Specification 906,170.