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.

Table 1: lens data

Table 2: lamp data

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
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.