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.
|
|
| 100/200 GLS | B.C. | S142AS | S142AN |
| 100/200 GLS | E.S. | S142BS | S142BN |
80/125 MB/U
80/125 MBF/U | 3-pin B.C. | S142CS | S142CN |
| Unless otherwise specified standard ¾ B.S.P. tapping will be supplied. |
| Dimensions, Tapping & Height |
| Height | 11½" |
| Diameter | 12" |
| Tapping B.S.P. | ¾ |
| Minimum length of thread required | 7/8" |
| Weight | 8 ½lbs. |
| Refractor Catalogue Numbers |
| Symmetrical | 4125 |
| Non-Axial | 2/4125 |
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
| Body | Silicon aluminium alloy LM6M, exterior finish aluminium, interior finish and underside of reflector white |
| Bridge piece | Mild steel cadmium plated |
| Refractor bowl | Crystal glass |
| Bowl retaining ring | Silicon aluminium alloy LM6M. Finish aluminium. |
| Hinge screws | Stainless steel |
| Wing nuts | Brass cadmium plated |
| Internal screws | Mild 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
| G.L.S. | MB/U |
| Beam Angle Horizontal | 170° | 170° |
| Beam Angle Vertical | 78° | 78° |
| Light output ratio | 76% | 76% |
| Light flux in lower hemisphere | 87% | 91% |
| Directional Intensity Ratio | 4.3 | 3.8 |
|
