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Argus II for Group 'A' Roads

Single piece dome refractor lantern with outer bowl

Crompton Lamps :-

300/500W.Tungsten filament(GLS)
125W.Mercury Fluorescent(MBF/V)

With an outer bowl to seal the interior against dust and weather, this simple but robust lantern embodies the following features:-

  • Automatic focusing of lamp and registration of refractor.
  • Quick release fastenings for bowl and refractor.
  • Internal single piece refractor in two distributions.

Lamp Wattage
and type
Complete Lantern Catalogue No.
300/500 GLSG.E.S.S170DSS170DN
125 MBF/VG.E.S.S170DSS170DN
Unless otherwise specified standard 1¼ B.S.P. tapping will be supplied.

Dimensions, Tapping & Height
Height15 ½"
Tapping B.S.P.1";
Minimum length of thread required1"

Refractor Catalogue Numbers

1. Construction

The reflector is cast in one piece with the body which is arranged for top entry and provided with two sets of tapped bosses for the fixing of the lampholder bridge assembly. This consists of a single piece bridge, carrying the lamp holder, with bayonet slots to engage fixing screws in the bosses. The bayonet slots allow the bridge to be changed from one set of bosses to the other or to be removed for wiring without complete withdrawal of the fixing screws.

The refractor is of the single piece dome type with prisms moulded on both its internal and external surfaces. Projecting studs from the refractor engage bayonet slots in the refractor retaining plate which is itself screwed to the lantern body casting. The arrangement of studs and retaining plate is such that the refractor can only be assembled with the correct angular location.

The outer bowl is carried in a hinged retaining ring which bears when closed on a felt gasket. Lugs on the ring engage with a wing-nut fastening fitted to the lantern body.

2. Material And Finish

BodySilicon aluminium alloy LM6M, exterior finish aluminium, interior finish white and underside of reflector white
RefractorCrystal glass
Outer bowlClear glass or 'Perspex'

3. Distribution

Typical Polar Curves and an Iso-Candle diagram for the most popular 2/4118 non-axial refractor are given in Figs. 1 and 2.

FIG. 1
Polar distribution for 2/4118 refractor with 500W 7930-lumen lamp
A: In vertical plane through the centre of the main beam
B: Plan distribution of 78° cone

FIG. 2
Iso-candle diagram for 2/4118 refractor with 500W. 7930-lumen lamp.

4. Focusing

The bosses to which the lampholder bridge should be fixed for each lamp size are clearly marked within the lantern.

5. Maintenance

The aluminium alloy from which this lantern is cast is highly resistant to corrosion in both industrial and marine atmospheres. Additional protection can be provided by occasional painting in service.

6. Optical Data For 2/4118 Refractor

Beam Angle Horizontal170°170°
Beam Angle Vertical78°80°
Light output ratio76%73%
Light flux in lower hemisphere86%81%
Directional Intensity Ratio5.62.6