The light in this series of locomotives has the head of the bulb pointed inward towards the reflector. There were rotating reflector Gyralite designs (ex.: 20350 Gyralite) which also had the bulb in this orientation.
photo by: Javier Fraile
photo by: Javier Fraile
The following photos by:
Santiago Gandara (Engineer)
Reflector diameter: 40"
Reflector (hole) to filament of bulb: 10"
based on other photos showing tape measure
Bulb assembly is hinged and wires run inside lower hinged support to bulb socket.
Notice how socket surrounds around lower half of bulb.
Bulb: 110V 150W
The high voltage and therefore thin filament mean the bulb filament support structure must be designed to withstand
mechanical vibration and shock of RR use.
The following excerpt is by
Javier Fraile
The headlight, including the reflector and its hole, is not accessible from inside the locomotive, because all you see from there is a metallic back-cover with some screws which were used to set the height of the light beam by adjusting the position of the reflector. The bulb checking and replacement were made from outside.
As far as lights were concerned, the crew only entered the "nose" of the locomotive --through a small door in the cab-- to change the color of the tail-lights. These are the upper lights with a clear lense. Inside, each has a bulb in vertical position with three filter-disks interposed: red, yellow and purple. These were switched from their usual position (red) to the other colors, if necessary, according to the old signaling regulations. The loco "noses" also contained the batteries and the air compressor and vacuum equipments.
Inverted Bulb fixture:
The Engineer (Santiago) figures the reason is as follows:
A bulb pointing outwards has a cone of light which comes out "uncontrolled", thus wasting optical
power toward unwanted directions.
Even more, in the case of cars, halogen bulbs usually have a "cap" to block these rays, I
guess to avoid blinding the drivers coming in the opposite direction. But this would be no
problem in a loco (in fact, you want to "blind" people to warn them). So the reason of placing the
bulb backwards would be efficiency. This is just a guess. Of course, a few almost-horizontal rays
are lost, but this is probably a minor loss.
Why the hole? Two possibilities.
1) To save reflecting material.
Since the rays through the hole would be lost anyway (if there were no hole, they would just
strike back the bulb), no reflector is necessary there.
2) The company that built the reflector made a "universal" one, with the normal hole to
place a bulb --only English Electric decided to set up the headlight differently.
It's obvious that such a solution has not succeeded, as I've never seen any other loco with such a lighting scheme ever since... Why, we don't know.
Definitely, the Brazilian locos did have a "reversed" headlight and "Vulcan Foundry" made the mechanical work. The Brazilian units are just a little older than the Spanish ones, and probably the most similar in design.
Alstom is a merge of the original French Alsthom company with a few old British companies
--including English Electric, the manufacturer of the 7700 locos.)
Many years ago. English Electric and other British railway constructors merged with the French company
Alsthom into a multinational consortium, which is now called "ALSTOM" (without the "h"). They also absorbed
a few small or medium-size Spanish railway companies, and now Alstom has a big factory in Spain too.
My friend the engineer told me he didn't find any label or legend whatsoever on any part of the 7700 headlight, so everything indicates that the headlights were made by the manufacturer of the locos itself: English Electric.
A probable explanation was so that it could also be used with traditionally mounted bulbs or possibly to help with heat dissipation. Since that area of the reflector would only shine light back onto the bulb and not through the lens, there is no need for a reflector in that particular area.
It's possible that the lamp designer was able to get more total light with the inverted bulb mounting, but the penalty is a large shadow straight ahead. So instead of having a sharp peak intensity, you'll have a more even distribution of light, but at a lower level.
Would more total light - be due to the increased exposure to the top of the filament to the reflector? (top of bulb aspect as well as sides ----- non inverted bulb would have only the sides or mostly side aspects)
Possibly. It really depends on the design. Have you ever seen a flashlight that has the bulb placed in the reflector normally but the lens has a small diameter of frosting directly in front of the bulb? This causes a small shadow in the beam which in turn makes for a more even distribution of light. I was thinking that you'd get the same effect by reversing the bulb and if the lamp designers were clever enough, they'd be able to have more control over the total distribution of light and hence have a greater total light output. But that's all speculation on my part. What's more likely, based on my experience with all sorts of lamp manufacturers, is that the lamp was designed in that way to be unique.
Douglas G. Cummins - Calcoast ITL
Javier Fraile:
This morning (4/2000), Enrique Robles, an engineer of steam locos (chief engineer of RENFE), called me and said he is sure that all steam locomotives he knew had the headlight arragement as in the 7700.
He told me that the Alsthom 7600 locomotives, which date back from about the same time as the 7700 (late 1950's) did already have the "normal" headlight, with the bulb screwed in at the base of the reflector. Incidentally, he commented that the problem of the 7600 headlight was that the 110 volt. bulb filament produced a big shadow which was projected ahead, and it was rather annoying.
No such a thing happened with the 7700, but, all the same, he says the lighting of the 7700 was rather defficient, because the light was not very well, evenly, distributed by the reflector, so there were shadows. Particularly, when the loco bounced up and down because of, say, a dip, the shadows would "dance" in front of the engineers, which was quite annoying and distracting.
He told me that he will be in trouble when the last replacement 110 volts-150 W bulb goes out. It's impossible to find those bulbs any more. He said they will have no choice other than to put a standard halogen 12 volts car bulb in, and set up the necessary electronics to get the 12 volts DC from the 110 volts AC. That fix has already been done with some preserved steam locomotives, he told me.
He is referring to Spain, I think. His father was a steam loco driver. The funny thing is, I don't remember seeing any electric loco other than the 7700 with that arrangement --despite he claims that it was "usual" in the 1920's-1940's period. I have pics of electric locos from the 1920's and later, and the headlights are "normal". (I've even seen them in the Museum.)
As for diesels, the first ones were the ALCO's 1600, from 1952 or so, and the headlight was typically American: standard dual light.
However, I have seen pics of Spanish old steam locos where the headlights MIGHT be of the inverted type. Unfortunately, this point is never quite clear.
Let me note that many of the Spanish steam locos were British imports or made in Spain under British companies license. That might explain the headlight system...
Javier Fraile:
Here's -at last- another loco with the same kind of headlight. It's a MZA 1701. The pic was taken at the Madrid museum in in 1989.
Crop of photo
The photo was taken in 1989 and the author's name as quoted in the "Hobbytren" magazine is Carlos Teixidor. The steam loco is no longer in the Museum (the pic is from 1989); it is now stranded in a RENFE freight station near Madrid. (In fact, Spanish railfans are worried about its lack of preservation.)
The other day I was watching a video about the last Mikados in Spain (in the mid- seventies). RENFE had as many as 200 mikados. These steam locos were originally Japanase, though most of the RENFE ones were built in Spain under licence. I also believe some were USA imports. In watching the video, I could spot at least ONE mikado with the inverted headlight arrangement.
In any event, it does seem that it was a common practice to use such a headlight arrangement in the steam locos in Spain during the 1940s and 1950s. My feeling is, this was a British influence (most of the railway network was first built in Spain by the British in the late XIXth century).
I learned that the steam loco whose pic I sent you was made in Spain by "Maquinista Terrestrey Marítima" in 1927. But I don't know if the design was English, America...
The following is a photo of one of English Electric locos exported to the Indian Railways in the 1950s (the equivalent to our 7700s). You can clearly see it has the same headlight.
photo by: Bharat Vohra and Siddharth Joshi
I received a mail from Angel Maestro, the expert in Railway Heritage. He tells me he was doing research, talking with former drivers of 7700s from the depots of Oviedo and Leon, some of them already retired. They gave him pieces of information that were contradictory some times. His conclusion is, the most likely hypothesis is that the headlight was made by English Electric; he is almost sure. (He really took a lot of trouble to find out.)
Incidentally, somebody just gave me a book as a present. It's about steam locomotives of all times. There I found several Indian and British steam locomotives with "inverted" headlight. So, such an arrangement seems to be British and date back from remote times... (As you know, it was the British that built the Indian railways.) There is also a pic of a Spanish steam loco with the same kind of headlight.
I once read that EE was the result of several old British companies joining, some of them being builders of steam locomotives.
English Electric made the Brazilian (the oldest), Spanish and two first series of the Indian locomotives in Great Britain. The Spanish 7700 indeed had the inverted headlight. So did the Indian locos, at least the first series. I *think* the Brazilian locomotives had the same arrangement too, but I'm not sure. There was also an Australian series (similar to the 2nd Indian series), which did NOT have the inverted arrangement. I don't know whether these locos were made in Australia under licence or imported from UK.
Finally, India still had one more class (WCM5), already built in India, but with EE electrical equipments and design. In a photo, the headlight is not well appreciated; I think the bulb's not inverted (?).It's hard to tell.
As for the Indian steam locos, I've seen quite a few photos showing
the inverted headlight (one of which is attached); since it was the
British that colonized India and started up the railways in this country,
everything leads us to conclude that the inverted headlight is of a remote British origin, and the "idea" reached anywhere
in the world where the British were (or sold)...: (Spain, Brazil, India...)
