Lever frame
[3]: 123 By the movement of individual levers (or sometimes cranks),[3]: 123 signals, points, track locks, level crossing gates or barriers and sometimes navigable movable bridges over waterways are operated via wires and rods.Lever handles are usually of polished, unpainted steel, and signalmen operate them with a cloth to prevent rusting from the sweat on their hands.This type of power frame has the disadvantage of a relatively low distance between points and signal box (approximately 200–250 m) and a slow operating speed.The two types also share the same disadvantages such as pressurized tubing having to run directly between the field appliance and the lever frame.Electric control of a hydraulic or pneumatic actuator in the field was far simpler and more reliable, allowing for a greater distance between signal box and points.Unlike a mechanical linkage, pneumatic or hydraulic lines could leak and cause points to drift out of correspondence with disastrous consequences.In North America this is known as "Switch-Signal" protection and any change in the position of a field appliance will immediately set the electric signals controlled by a power frame to danger.
Knockcrogheryrailway signallingsignalspointssignal boxsignalmanpointsmanSpencer Street No.1 signal box in Melbourne, AustraliaSevern Bridge JunctionShrewsburyKyle of LochalshAnnett's keylevel crossingmovable bridgesinterlockingLüdinghausen railway stationmechanical advantageswitch pointssolenoidsUnion Switch & SignalWestinghouse Air Brake CompanyGeneral Railway Signalcounter-electromotive forceopen loop systemsIsle of Wight Steam RailwayMcKenzie & HollandGreat Eastern RailwayIntegrated Electronic Control CentreSouth Devon Railway AssociationBlock systemsAbsolute block signallingAutomatic block signalingCentralized traffic controlCommunications-based train controlDirect traffic controlEuropean Train Control SystemMoving blockRadio Electronic Token BlockTrack Warrant ControlTrain order operationSignalling controlBlock postRail operating centreSolid State InterlockingWestlock InterlockingApplication of railway signalsCab signallingNorth American railroad signalsRailway semaphore signalAxle counterTrack circuitTrack circuit interrupterTreadleTrain protectionAdvanced Civil Speed Enforcement SystemAutomatic train controlAutomatic train operationAutomatic train protectionAutomatic Train Protection (United Kingdom)Automatic train stopAutomatic Warning SystemAutomatische treinbeïnvloedingBaliseCatch pointsChinese 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 AmericaNorwayPolandSwedenSwitzerlandThailand