Automatic Colour Light Signalling Systems

A type of signal that uses colored lights to display different aspects, both by day and night. They are typically made of cast iron, sheet metal, or fiber reinforced plastic.

A type of CLS unit that avoids "phantom" effects in sunlight by using multiple light units. They can have 2, 3, or 4 units, depending on the number of aspects displayed.

A light unit in a CLS that is precisely focused to align the beam of light towards the driver. This is achieved using a doublet combination of two lenses, with the colored lens inside and the clear lens outside.

A type of CLS unit where a separate light unit is provided for each aspect. The light units are generally arranged vertically, with the green aspect on top, yellow in the middle, and red at the bottom.

The arrangement of aligning the light unit so the beam shines in the direction of the approaching train. It's done using sighting apertures and adjusting bolts on the mounting socket.

A combination of two lenses used in CLS to collect light from the lamp and refract it into a parallel beam of light. The colored lens is the inner one, while the outer lens is clear.

A special type of lens in CLS with angled surfaces that deflect some of the light to provide better visibility for drivers standing very close to the signal.

A type of CLS unit where the outer lens has a deflecting prism to divert a part of the light into a subsidiary beam at an angle. The prism's location is chosen to give the best close-up indication to drivers.

A standard type of lamp used in CLS. It consists of a coiled tungsten wire (filament) that glows when heated by an electric current.

The amount of light produced by a lamp, measured in lumens. It's directly related to the temperature of the filament.

The efficiency of a lamp, measured in lumens per watt. It determines how much light is produced per unit of electricity used.

The relationship between the voltage applied to a lamp and the light output and lifespan. Higher voltage increases light output and efficiency but reduces lifespan.

A higher current density in a filament. This results in higher temperatures, leading to increased light output and efficiency.

A type of signal lamp with two filaments within the same envelope. One is the main filament, and the other is an auxiliary filament that lights up if the main filament fails. This is used for safety when cascading systems aren't possible.

A type of signal lamp with two filaments connected in parallel. Both filaments are always lit.

A type of signal lamp with two filaments connected independently. The auxiliary filament is only used when the main filament fails.

A relay that monitors the main filament of a triple pole lamp. It drops when the main filament fails, switching the auxiliary filament on.

A method for repeating the signal aspects in the cabin. A current transformer connected in the signal lamp circuit is used to provide a secondary current that controls an indication lamp.

A method for signal indication where a current transformer (L-type or H-type) is connected in series with the signal lamp circuit. The transformer's secondary develops a voltage that is used to control a lamp-checking relay (ECR).

A type of current transformer used in the ECR method. It is suitable for low currents (around 300 mA).

A type of current transformer used in the ECR method. It is suitable for high currents (around 2.5 A).

A type of signal that provides drivers with a warning about an upcoming stop signal. It is located at a certain distance in advance of the stop signal.

A type of signal that provides additional warning about an upcoming stop signal when the distance between the main distant signal and the home signal is too long. It is located at 1 km in advance of the main distant signal.

A visual indication placed alongside the track, indicating the presence of a distant signal. It alerts drivers about the braking distance required for approaching signals. It is not needed when an inner distant signal is provided.

A type of signal that combines the aspects of an inner distant signal and a home signal or other signal functions. This is used to reduce signal clutter and improve efficiency.

A type of light source used in signals. LEDs offer several advantages over traditional filament lamps, including longer lifespan, lower energy consumption, and greater resilience.

A semiconductor device that converts electrical energy into light. LEDs have different colors depending on the materials used in their construction.

A group of LEDs arranged in a specific way to provide a signal aspect. The LEDs are arranged in arrays, and the failure of a single LED does not render the whole unit blank.

A device that regulates the current flowing to LEDs in a signal unit. It ensures a constant current flow, regardless of voltage fluctuations, providing stable and reliable light output.

A component in an LED signal unit that uses optical sensors to detect signal blanking or dimming. It triggers an alarm and/or cuts off the aspect to prevent safety issues.

A combination of multiple LEDs arranged to provide a signal aspect. The array's design ensures that the failure of some LEDs does not compromise the visual integrity of the signal.