Treadle (railway)
In railway signalling, a treadle is a mechanical or electrical device that detects that a train wheel has passed a particular location.In situations where track circuits are unreliable due to rusty rails, for example adjacent to buffer stops and catch points, a long treadle bar is used.It remains depressed for a period of several seconds, so that a train with many axles does not unduly damage the unit.An electronic treadle uses the disruption of an electromagnetic field to detect an axle, rather than a depression bar.[2] The biggest flaw in the Whitworth automatic signal is probably that it had no redundancy, and a single stone might jam it.
railway signallingtrack circuitlevel crossingbuffer stopscatch pointsaxle countersignalNew South WalesHawes Junction rail crashlevel crossingssignalmanClayton TunnelClayton Tunnel rail crashTrack circuit interrupterInduction loopBlock systemsAbsolute block signallingAutomatic block signalingCentralized traffic controlCommunications-based train controlDirect traffic controlEuropean Train Control SystemMoving blockRadio Electronic Token BlockTrack Warrant ControlTrain order operationSignalling controlBlock postIntegrated Electronic Control CentreInterlockingLever frameRail operating centreSolid State InterlockingWestlock InterlockingSignalsApplication of railway signalsCab signallingNorth American railroad signalsRailway semaphore signalTrain protectionAdvanced Civil Speed Enforcement SystemAutomatic train controlAutomatic train operationAutomatic train protectionAutomatic Train Protection (United Kingdom)Automatic train stopAutomatic Warning SystemAutomatische treinbeïnvloedingBaliseChinese Train Control SystemCityflo 650 CBTCContinuous Automatic Warning SystemContrôle de vitesse par balisesEBICABIntegra-SignumInteroperable Communications Based SignalingCrocodileKorean Train Control SystemLinienzugbeeinflussungPositive Train ControlPulse code cab signalingPunktförmige ZugbeeinflussungRS4 CodiciSelTracSistema Controllo Marcia TrenoSlide fenceTrain automatic stopping controllerTrain Protection & Warning SystemTrain stopTrainguard MTTransmission balise-locomotiveTransmission voie-machineLevel crossing signalsCrossbuckWigwagE-signalWayside hornAdtranzAlstomAŽD PrahaFederalGeneral ElectricGriswoldHitachiHyundai RotemMagneticProgress RailSafetranSiemensSmith and YardleyThalesUnion SwitchWestinghouse Brake & SignalWestinghouse Rail SystemsTransport CanadaAustraliaBavariaBelgiumCanadaFinlandFranceGermanyGreeceNetherlandsNew ZealandNorth AmericaNorwayPolandSwedenSwitzerlandThailandUnited Kingdom