Signalling Units

Signalling Units

Route/Shunt Signal Unit:

  • The light unit case is manufactured from a light alloy material.
  • The lamp housing is weatherproof and well ventilated to minimise condensation. The cover is easily removable for inspection and maintenance.
  • The lamp unit is equipped to take a lamp rated at 110 v 25W and fitted with a 3-pin cap to BS specification 469: 1960 (lamp ref. 8L33).
  • For a route signal, an additional frosted lens with clear inner is fitted, and for shunt signals, a fully frosted lens is fitted.

Colour light signal lamp unit:

  • The colour light signal lamp unit is a low-cost unit providing multi-aspect railway signals.
  • It is highly corrosion resistant and exceeds TRANSNET specifications.
  • This durable unit comprises a lamp housing, hinged rear cover, mounting ring and light hood assembly.
  • The top rear cover allows full access to accommodate cleaning and lamp replacement. During operation, the lid is tightly closed and may be padlocked.
  • The 465 mm light hood shields 240 degrees of the outer lens perimeter. A variety of lamp types may be fitted but lamps are not normally supplied with the unit.

Lens system:

  • The lens system has two prismatic lenses that are dust-sealed and factory mounted in the housing.
  • For close-up observation they show reflection, which may cause ‘phantom’ colour aspects.
  • The lenses are optical glass.
  • The studs, springs, washers and lock nuts in the mounting ring and alignment adjuster are stainless steel.
  • Other fasteners in the assembly are also stainless steel.
  • The lamp holder terminals are nickel-plated brass.

Lens Data:

  • Colour Specification Beam Divergence
  • Red BR 820 4 degrees
  • Yellow BR 820 4 degrees
  • Green BR 820 4 degrees
  • Lunar White BR 820 4 degrees
  • Blue Signalling BL 30 (German) 4 degrees

Lamp data:

  • Type Main Filament Aux Filament Specification
  • Volts Watts Volts Watts
  • 5L33 110 25
  • 5L34 12 24 12 16 B55469.1960
  • SL35 12 24 12 24 B55469.1960

Mechanical mounting:

  • The mounting plate serves as a frame and is fixed to face down track.
  • The units are then individually aligned and locked. Installation is via cable access to the housing.
  • This is a 20 mm diameter armour grip cable gland and weatherproof neoprene shroud.
  • The top hinged cover allows good maintenance access to the unit, making cleaning and lamp replacement easy.

Focus and alignment:

  • Each colour unit is individually aligned after mounting, using two sighting holes in the housing. These are factory-set for accuracy.
  • The body is attached to the mounting ring by studs, springs, washers and lock nuts. They allow the unit’s alignment to be adjusted after installation.


  • Ventilation happens through two fine wire-mesh filters situated in the cover and the housing.
  • These inhibit condensation without allowing the passage of light.

Materials and finish:

The main unit components are Black UV Protected Glass filled nylon for high impact resistance. They are finished with two coats of matt black paint.