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Taurus I for Group 'B' Roads

Bowl refractor lantern

Crompton Lamps :-

100/200W.Tungsten filament(GLS)
80/125W.Mercury Electric Discharge(MB/U)
80/125W.Mercury Fluorescent Discharge(MBF/U)

This simple but robust lantern embodies the following features:-

  • Automatic focusing of lamp and registration of refractor.
  • Dustproof lantern construction.
  • Single piece bowl refractor with external surface mainly smooth.

Lamp Wattage
and type
Complete Lantern Catalogue No.
100/200 GLSB.C.S142ASS142AN
100/200 GLSE.S.S142BSS142BN
80/125 MB/U
80/125 MBF/U
3-pin B.C.S142CSS142CN
Unless otherwise specified standard ¾ B.S.P. tapping will be supplied.

Dimensions, Tapping & Height
Tapping B.S.P.¾
Minimum length of thread required7/8"
Weight8 ½lbs.

Refractor Catalogue Numbers

1. Construction

There are only four main parts, viz. body casting, lampholder bridge assembly, refractor bowl and bowl retaining ring. The reflector is cast with the body which is arranged for top entry and provided with three sets of tapped bosses for the fixing of the lampholder bridge assembly. This consists of a single bridge piece, carrying the lampholder, 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 another or to be removed for wiring without complex withdrawal of the fixing screws.

The refractor used with this lantern is of the single piece bowl type with prisms on the internal surface, the external surface being mainly smooth. Correct angular location of hte bowl is ensured by the engagement of a projection on the bowl with a cut-out in the bowl retaining ring while two gaskets are fitted to prevent the ingress of dust.

The retaining ring, hinged to the body casting, is provided with lugs to engage with a self-retaining wing-nut fastening on the lantern body.

2. Material And Finish

BodySilicon aluminium alloy LM6M, exterior finish aluminium, interior finish and underside of reflector white
Bridge pieceMild steel cadmium plated
Refractor bowlCrystal glass
Bowl retaining ringSilicon aluminium alloy LM6M. Finish aluminium.
Hinge screwsStainless steel
Wing nutsBrass cadmium plated
Internal screwsMild steel cadmium plated

3. Distribution

Typical Polar Curves and an Iso-Candle diagram for the 2/4125 refractor bowl are given in Figs. 1 and 2.

FIG. 1
Polar distribution for 2/4125 refractor with 200W 2880-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 2/4125 refractor with 200 W. 2880-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 2/4125 Refractor

Beam Angle Horizontal170°170°
Beam Angle Vertical78°78°
Light output ratio76%76%
Light flux in lower hemisphere87%91%
Directional Intensity Ratio4.33.8