The Mars Light cases, doors, or 8-3/8” lenses are not interchangeable with those of the Gyralite. The Gyralite lenses in the dual units as well as the single units currently marketed have a diameter of 7-9/16". The lenses in the Mars Light units used both diameters: The dual units which utilized cases having lenses mounted in the cover, used the 8-3/8” diameter lenses. The dual units which were mounted behind the porthole glass in F/E units – used the 7-9/16” diameter lenses. The Mars Light company secured the sealed beam lamps to the bulb support by a ring which was secured by spring bars. If it was intended that the unit be used in F/E locomotives, this ring (SBWR-1006) would have 4 threaded holes (2 on each side) to affix another ring to which the glass lens was secured. This ring encircled the outer lip on the exposed side of the lens. The bulb securing ring which was supplied without these threaded holes was part No. 168020
The information on the Mars Lights is limited. I am still researching these lights. I have not seen any Locomotive Cyclopedia with anything manufactured by the Mars Signal Light Co. Apparently, Mars did not like to advertise, which does not help things either. The bulletins, referenced below, were most helpful in sorting out the models of the Mars Lights found on locomotives which are now a fading memory. Many thanks are directed to Trans-Lite, Inc., for its help in furnishing this much needed information.
Mars Signal Light Co. - Bulletins:
furnished by Trans-Lite, Inc.
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SB-2000 |
GWR-5000 |
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SB-3000 |
WR-816 |
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SB-5000 |
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SB-6000 |
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SB-8000 |
WR-5000-A |
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SB-9000 |
R-250 |
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SB-R-250 |
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Tri-Eight Signal Light |
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SBWR-5000-1 |
RE-12 |
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SBWR-2-300 |
SB-RE-12 |
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SBW-2-300 |
OS-250-RE-14 |
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SBWR-2-301 |
SB-OS-250-RE-14 |
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SBW-2-301 |
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manual switches: |
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SBRE-100 |
SB-100 |
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" " 101 |
WR-1000 |
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" " 102 |
air pressure controls: |
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" " 103 |
510 |
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" " 104 |
520 |
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" " 105 |
530 |
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" " 106 |
axle-generator control: |
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" " 107 |
A-601 |
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" " 108 |
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" " 109 |
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SBB1-100 |
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" " 101 |
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" " 102 |
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" " 103 |
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" " 104 |
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" " 105 |
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" " 110 |
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Information on the following was contributed to by Kevin Holland, Scott J. Whitney, Griffin Hamilton, and Trans-Lite, Inc.
The lowest point of the beam pattern for locomotive Gyralites was the point at which the light beam was projected straight ahead and equidistant from the tracks. The locomotive Mars "figure 8" units had a dip on each side of this equidistant point which was promoted as illuminating crossings below grade.
The following abbreviations are applied to the
Mars Lights:
"SB"=sealed beam; "WR"=white-red; "2"=dual. The Mars Light: SB-WR-2-300, would be a sealed beam, white-red, dual bulb unit with a "300" model designation. A possibility for "RE" would be REd or a grouping originally designed as REar train signal lights which ended up being marketed for locomotive use as well. (RE-12, SBRE-100).
Note:
The tags found on the Mars units may not indicate the true nature of the unit
as documented in the paperwork. From what I and others have found, the tag on a
SBRE-100 unit may represent any unit in the class which would include SBRE-100
to SBRE-109 portable units and SBB1-100 to SBB1-105, SBB1-110 built-in units. I
found a 64 volt built-in unit with a SBRE-100 Mars tag. This unit would have
been documented on paper as SBB1-102 or SBB1-103 (depending on whether manual
(102) or automatic (103) operation. The dual 300 Mars Lights follow this
pattern also. A non-flanged (300) or flanged (301) unit will have identical
tags if the mechanism is identical, even though on paper, they are listed as
having unique suffixes of "300" or "301". The label
classification of these lights will be used in most cases to describe these
units to aid in the dealing with similar units collectively. Also, Mars labeled
motors with the battery voltage. Therefore the value of 64 volts is found
instead of the 72/74 charging voltage listed in other units. Voltage ranges of
64-74 volts has been transcribed from literature in referenced units below.
The following types of Mars Lights were found to have been used:
A cylindrical "figure 8" unit which mounted on a steam locomotive having a tapered back portion. The unit had a rail sliding mechanism to slide mechanism forward from case. This unit is illustrated in US Pat. 2,234,600 and accompanying photos.
AWR-12-2/SB-AWR-12-2 were used a stationary white back up light in addition to and oscillating "figure 8" red light. A red glass door is latched into position to produce the red light beam. To produce a beam of white light, the door is swung open and retained into this position by a spring latch. By selecting "Stationary Light" by way of the control, the oscillation of the motor is stopped and the beam may be placed parallel to the track. Voltages from 12 - 110 volts were available and the reflector in the AWR-12-2 unit was 10 inches in diameter. This light is listed for "Portable Application".
OS-250-RE-14/SB-OS-250-RE-14 was a Mars Combination Oscillating Red and Stationary White Back-up Light. This light is listed for "Built-in Application". The unit performs the functions of the above unit. There are 2 motors in this unit. One motor provides the “figure 8” pattern and the other provides rotation to change from an oscillating "figure 8" red light to a stationary white back-up light, or vice versa. The rotational aspects of switching lights is similar to that of the WR-5000-A.
R-250/SB-R-250 “figure 8” lights were available with a bulb-reflector combination or the sealed beam lamp. It was also supplied with either the red lens for emergency conditions or a clear lens for warning at highway crossings.
This light was the type used on the 8444 UP 4-8-4. It used a reflector and incandescent bulb mounted in a circular housing. It also used a Red lens, but apparently a clear lens was also available. The Nickel Plate Berkshire No. 779 used this type with a clear lens before being fitted with the sealed beam version described below.
As delivered from Mars, the Nickel Plate units originally had clear convex lenses, which were in many cases replaced (breakage) by Nickel Plate shop crews with flat glass inserts through the mid and late 1950s.
The SB-R-250 was the
sealed beam version of the R-250 used on all the Nickel Plate steam
locomotives. The units on the Nickel Plate Berkshires all had the clear lens.
It should be noted that any Mars Light in a Berkshire other than a R-250 with a
Clear lens or a SB-R-250 is incorrect . (I have seen a drawing of a Berkshire
with a dual white-red oscillating light unit). The SB-R-250 (red lens) was used
by C&NW. The red lens is what this light has unless the clear lens is
specified.
The housing for both the above units has a characteristic bevel, tapering toward a narrow flat, verticle face (inside which the motor is mounted vertically). Three cast-integral legs support the housing (one rear, two at the front). Conduit enters through the top of the flat rear panel..
SBRE/SBB1
“figure 8” units competed in the RR market with the Pyle-National's 175x0
Gyralites. It was a square, 
box unit. SP used this
type unit on its road and switcher locomotives. The locomotive version was
listed as having a 64 volt AC-DC motor. These apparently worked fine with no
dropping resistor from the 72/74 volt locomotive supply.
This light was available as a portable and built-in unit. The portable version was available with a hanger bracket which permitted hanging of the light on the conventional type of collapsible tail gate, observation, or business car platform. There is a clamping bar which is threaded adjustment to permit adjusting the light beam parallel to the track . Models ranged from SBRE-100 - SBRE-109. The voltages ranged from 12 - 110 volts.
The light was also available in a built-in version. These units were denoted with the prefix "SBB1" Models ranged from SBB1-100 - SBB1- 105 and SBB1-110. The voltages ranged from 12 - 110 volts.
This type Mars Light was also used by shortlines like the Vermont Railway, on road and switcher locomotives, as well as several RDCs and passenger cars, with either red or clear lenses.
The SB-R-250 and SBRE/SBB1 mechanisms are similar but the in the SB-R-250 the sealed beam and its retainer are suspended in an additional, larger diameter, four piece cast metal ring that presumably helps insulate everything from the extreme motion. The sealed beam retainer assembly is somewhat heavier and a slightly different design than that of the SBRE/SBB1.
RE-12/SB-RE- 12 “figure 8” units used on both locomotives (cited as used on C&NW below) and railcars These units were available as both portable and built-in versions. The bulb reflector combination used a 10 or 12 inch reflector.
WR-5000-A “figure 8” light was a cylindrical unit the mechanism incorporated 2 motors, one which could bring either a clear or red light into registry. These were all 12 volt units powered by a dynamotor.
.
Tri-Eight Signal Light consisted of three PAR-56 30V 200W bulbs. The configuration is an inverted triangle with the top pair of bulbs are used for white light and the bottom for red. A separate resistor is provided for each of the bulbs to allow the unit to remain functional if one bulb burns out (bulbs wired in parallel). The beam pattern is a horizontal "figure 8", insuring that the beam strikes the highway regardless of whether the the crossing is above, below, or at grade. The appearance of this unit is analogous to the 20775 Gyralite only the triangle is inverted. This light operates on the 64- 74 volt locomotive voltage
.
SBWR-5000-1
consisted of a 2 sealed beam bulbs, one producing white light and the other
red. A conversion unit was available to convert the Mars WR-5000-A 12 volt
lights to eliminate dynamotors and reduce expense. This light operates on the
64-74 volt locomotive voltage. This was essentially a Mars 300 mechanism (see
below) mounted for internal use in E & F locomotives. The Chicago
Burlington and Quincy No. 9911A E5 has this light installed in the upper
headlight opening. The Wabash No.1189 F7 at the Monticello RR Museum uses the
remnants of this light with the mounting of a Mars 300 mechanism being back
plate mounted to SBWR-5000 backplate via spacers and bolts.
Mars Reflector Lights (WR-816/GWR-5000):
The WR-816 and GWR-5000 will be discussed together due to their similarities.
Mars WR-816 "figure 8" Light used a stationary light source and a reflector whose motion produces a projected "figure 8" pattern.
The GWR-5000 Gyrating Signal Light was very closely associated to the Pyle- National rotating reflector Gyralites in design and pattern. This unit uses a stationary bulb and socket which eliminates flexing lead wires or moving contacts. A 16 inch Alzak reflector is rotated about the light source.
In combination Red and White signal lights, the change from white to red is accomplished using a butterfly type of shutter which is placed ahead of the light source and is designed to cover the entire face of the reflector in the Red condition. In the White condition, the shutter is folded back against a baffle plate which also supports the bulb's socket. The red shutter is pivoted at the top and bottom on ball bearings. The two leaves of this shutter are geared together to act on unison on activation of a separate motor.
There are 2
motors used in both these units. One motor is used to produce oscillation of
the light beam, while the other operates the red shutter. In the event that the
oscillating motor fails, the projection of red light will still be possible
using the other motor to operate the shutter.
A blackout relay is provided to open the headlight circuit when the shutter is closed to generate a red beam of light. These lights are available without a red shutter for use at highway crossings only.
Mars dual Sealed Beam Lights
(dual 200/dual 300 models):
SB-WR-2- 200 "figure 8" Mars Light light was marketed in both a cased as well as an internal mounted versions It seems that this light was marketed as a both a Clear-Red as well as a dual-Clear unit. The red lens as well as the relay was removed (2 clear lenses used) to run both lamps energized for single track operation by some RRs (Green Mt. RR). The dual-Clear option offered by Mars as is evidenced by “builder’s shots” from C&O (see C&O photo page) and photos of the Rio Grande’s F7s and F9s (see discussion on Rio Grande use) showing the internally mounted dual-Clear units. All the units I have seen had the 32-volt motors (other voltages could have been possible). A photo of the Wabash No. 1143-A F7A also shows this light unit (Clear-Red) inside the upper headlight opening
. .
Users of the Mars 200 Light as white-red included:
SB-300 Lights: 
Units without a flange:
SBWR-2-300
SBW-2-300
Units with a flange:
SBWR-2-301
SBW-2-301
For simplification, the lights with the flange (301) will be collectively discussed under the the "300" label.
SBW-2-300 "figure 8" Mars Light. It appears that the light was marketed as a dual clear unit. The mounting of this unit was seen as both recessed (with a flange) as well as back mounted. D&RGW preferred to run this light.
The dual units above competed in the RR market with Pyle-National's 20585 Gyralite.
A standard light package for a GP-9 might include a Mars setup using a SBW-2-300 with the SBRE-100. The Pyle-National setup would be a 20585 Gyralite and perhaps a 17570 Gyralite.
Users of the Mars 300 Lights:
·
The
Florida East Coast is listed as users of Mars SB-WR-2-200's; they also used
different 300's on later engines, eventually switching over to the Oscitrol (!)
light sometime in the mid-to-late 1970's.
·
Monon
mounted a red/white Mars 300 in the nose of some of its ALCo C-628's
·
Seaboard
Coast Line mounted a red/white Mars 300 between the numberboards on some of its
SDP35's
·
And
oddly enough, the Southern Pacific may have had red/white Mars 300's in the
nose of some of its ALCo C-628's
Griffin Hamilton
Milwaukee Road
I did some more digging and found ample evidence that (once again) "Gyralite" may not necessarily mean Gyralite. It is now my contention that the Milwaukee Road FP45's came out of LaGrange with Mars lights, not Gyralites, is now my contention that the Milwaukee Road FP45's came out of LaGrange with Mars lights, not Gyralites, despite the other information I had on the units. What is more, they had the clear lens at the upper position "like all good Mars lights". There are some photos out on the net that show dual clear applications, but I will bet that this was due to replacement of broken roundels
Griffin Hamilton
They used a Red/Clear MARS unit in their FP45's. These were used in passenger service initially until Amtrak came about.
Bill Kaufman
There were also "hybrid" Mars
Lights.These were Mars units composed by the particular railroad using Mars
Light components to make up their own unique light unit. One such unit is that
in the SP 4449. This light uses a dual Mars headlight bulb plate (as in the
Mars SB- 9000 headlight - US Pat. 2,494,652) which has been affixed to a 12
volt Mars "figure 8" mechanism which was marketed for single bulb
use. It also uses auto headlight bulbs instead of the locomotive lamps (see photo page). The
original oscillating mechanism was a “Type 400” Mars Light (from the titile
on a drawing of this light) and was patented as US Pat. 2,234,600.
Users of the Mars Light:
·
Nickel
Plate Road was a major user of Mars lights from 1947 through 1964 in locomotive
(steam & diesel), passenger, and caboose service.
·
Wabash
would also make the Mars list, for locomotive and passenger use.
·
Norfolk
& Western appears to have eventually deactivated these lights following the
October 1964 merger..
·
Ontario
Northland's 22 FP7As came from the factory with dual red/white rear warning
lights - again, not sure whether Pyle or Mars.
Kevin Holland
C&NW Use:
I kept some pages from the classification book issued by the C&NW's Chief Mech. Engr. in the 1970's; although it is only a partial list, it tells Mars lights were in certain units at the time:
·
#5019-B
(EMD E-8) had a "MARS WR-816-1 SIGNAL LIGHT"
·
#5012
A&B, 5013 A&B, 5015 A&B, 5016 A, 5017 A, 5018 A&B, 5019 A and
5020A (EMD E-7) had "1 MARS RED AND WHITE SIGNAL LIGHT"
·
#4051-A
to 4054-A (FP-9(M)) had a "MARS WR-816-1 SIGNAL LIGHT"
·
#1619
&1620 (Alco RSD-4) had "1 MARS SIGNAL LIGHT"
·
#1694
& 1695 (FM H16-66) had "2 SIGNAL LIGHTS, MARS NO. SB-2000M"
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#1691
to 1693 (FM H16-66) had "2 SIGNAL LIGHTS, MARS NO. SB-2000M"
·
#1674
to 1683 (FM H16-66) had "2 SIGNAL LIGHTS, MARS NO. SB-2000M"
·
#1605
to 1612 (FM H16-66) had "1 MARS SIGNAL LIGHT"
·
#1557
to 1559, 1562 to 1599, 1601 to 1603, C.St. P. & O. 157 to 161 (EMD GP-7)
had "1 MARS SIGNAL LIGHT" (this was a big unit mounted above the
upper edge of the short hood
·
#1556
(EMD GP-7) had "1 MARS SIGNAL LIGHT" (this was a big unit mounted
above the upper edge of the short hood
·
#1525
to 1550, C.St. P. & O. 151 to 156 (EMD GP-7) had "1 MARS SIGNAL LIGHT
250W, RE-12" (mounted on the short hood above the headlight)
·
#1521
to 1524 (EMD GP-7) had "1 MARS SIGNAL LIGHT 250W, RE-12" (mounted on
the short hood above the headlight)
In that partial listing of C&NW Mars lights, there was no notation whatsoever of dual 300 lights on either the GP30 sheet or the SD40 sheet (for the ex-CGW units). Evidently, nobody cared enough about making the notations on them. These were the only GP30's and SD40's on the C&NW that were ever equipped with Mars lights, the original C&NW units not having them.
Just a guess, but I think most of these ex-CGW units equipped with the Mars 300 kept the lights as a matter of course, but those units that suffered collision damage (or some other major damage) to the light got the light pulled and blanked out. By the 1980's, about the only Mars lights left on any freight units were the ex-CGW units that had managed to keep them (whether they were complete inside or not).
Griffin Hamilton
The Mars SB-2000 was a single headlight unit comparable to a "ditch light". If used for signaling purposes, it must have used a red glass roundel over the bulb. C&NW also used Pyle-National's C-1785-RB "ditch light" for signaling purposes. This had the red roundel over the sealed beam. (also mentioned on Ditch-Crossing Lights page)
C&NW use of the R-250 (and sealed beam derivative):
Griff found photos of C&NW locomotive use:
The 1953 "Trains" magazine shows C&NW steam locomotive No. 514 with the R- 250 mounted on the top of the smokebox.
Aug. 1957 "Trains" shows C&NW No. 1537 with a modified mounting for the R-250 case. A pipe having an inside diameter to accommodate the R-250 case with a flange is used for mounting. The R-250 case is inserted into the pipe and secured. The other end with the flange is bolted to the front of the locomotive as near the roof. The twin sealed beam headlight is mounted below. Since this was the sealed beam era, the light was probably a sealed beam. The photo shows the 2 front brackets of the R-250 case.
Mar. 1966 "Trains shows C&NW No. 1565 with a roof mounted R-250 case. Again, this is most likely the sealed beam version.
The 1537 and 1565 are both GP7's, and like most of the C&NW's originally-purchased GP7's and GP9's built before about 1953, they had a red signal light. Somewhere along the line, the red "ditch light" got put on stuff, but I don't know the when or how of that decision.
This "ditch light" is the C-1785-RB red light that was found in the nose of the C&NW locomotives. This light is discussed on the Ditch- Crossing Lights page.
I can tell you that a lot of the red signal lights were removed and pitched into the scrap gons when the GP7-9 fleet went into the shops for heavy rebuilding starting in 1971. Most of the GP's got chopped noses during the rebuilds, and PRESTO! The lights were gone. Some of the Alco's and F-M's kept their lights up until the end of the line, as they were not rebuilt in large programs like the EMD's.
By the time I started paying attention to the details (around 1983), the red signal lights history. Except for the surviving nose-mounted 300's on what was left of the ex-CGW GP30/SD40 fleet, I can't recall a single one surviving. I took a considerable number of slides of the C&NW in the 1980's, and not one of them shows a Mars or Trans-Lite signal light, again, with the occasional (rare!) ex-CGW GP30/SD40 exception.
The two ex-CGW GP7's that made it to the C&NW (#120, 121) appear to have been originally equipped with SB-WR-2-200 lights, but the GP30's/SD40's had the SB-WR-2-300's, which makes chronological sense.
The C&NW had plenty of double track mileage back then, so some sort of red light was probably a good idea, especially considering how poor communications could be at times. For all I know, the reason for the disappearance of the "red ditch lights" may have had more to do with improved radio and dispatching than anything else (I am speculating here).
With the chopped noses, there was also not much room to put stuff, so maybe that was a factor, too... and the use of the beacons may have had something to do with it, since they started showing up around the same time. Interestingly, in looking for those photos, I saw a shot of a GP7 with a Tomar strobe mounted on a "gumball machine" base, just as I remembered them doing.
Griffin Hamilton
Rio Grande Use :
The Rio Grande used Mars signal lights on all of its cab units, starting with its FTs of 1941. In all cases the Mars light was mounted in the nose, with the headlight mounted below in the door. All of the Grande's PAs, FTs, F3s, F5s and all F7s through unit 5644 were delivered with WR-5000 Mars Lights,. F7s 5651-5694 were delivered with white over red dual-lens Mars lights in the nose (SB-WR-2-200), but these were quickly changed to dual white. F7s 5701-5764 and the F9s were delivered with dual white lenses (SB-WR-2-200 – dual Clear option). [There is also the possibilty of the SBWR-5000 lights being used or at least some conversion units of this model to update former WR-5000s – dual Clear option]. Two earlier units were wrecked and fitted with dual lights when rebuilt, 5481 and 5571. Krauss-Maffei units 4000-4003 came with dual-white lenses in the nose as well.
None of the Grande's switchers or early road switchers came with signal lights or had them applied, so their GP30s were the first roadswitchers to be delivered with nose-mounted dual white Mars lights (SBW-2-301). All subsequent road units were so equipped (GP35s, GP40s, SD45s) through GP40-2 3128 and SD40T-2 5385.
Subsequent units were delivered with Gyralites: GP40-2s 3129-3130, SD40T-2s 5386-5413, and SD50s 5414-5433, and several older units are known to have received replacement Gyralites as well. GP60s 3154-3156 and the second-hand Conrail GP40s did not have signal lights applied.
Jim Eager
Missouri Pacific Use:
The Missouri Pacific used nose-mounted dual-white Mars lights on some of their 6000-series dynamic brake-equipped SD40-2s (6000-6019?) bought for pool unit coal train service.
Jim Eager
The Mars SB-WR-2- 200 Light:
The case houses the lenses. Incidentally, the 8-3/8" clear lenses are very hard to find. The red is easy as it is the same as used in a semaphore signal. The front case is held by two knurled knobs with 3/8" male thread behind. We changed ours to a stud setup so we could use nuts and lockwashers outside the case. Inside the two shafts that hold the cover go all the way to the rear mounting plate. The mechanism is mounted to the mounting plate on a Mars Light while on a Pyle Gyralite, the studs (as well as a small pair of steel runners on the sides of the case) hold the entire mechanism. A Mars Light would have to be serviced on the locomotive or the whole unit removed. A Pyle Gyralite can have just the mechanism removed which is VERY easy.
Also, the Pyle front lenses are different from a Mars. RED ones are easy to get. They are still available today from the folks with the "Semaphore page" (www.semaphores.com) who are having Corning make them again. However, they didn't have clear ones made. High temp flat glass can be custom ordered to replace these clear ones, though. We have one unit so equipped. As to the two clear vs. red/clear, I think this was a function of the railroad's operations. The purpose of the red was to serve as a warning whenever a train went into emergency on double track. An opposing train would see this and could take action to prevent collision with derailed equipment. I think that the red could also be manually operated. If a railroad was predominately single track, there would be little use for a red lens.
Scott J. Whitney
The Mars SB-WR-2- 300 Light or Mars SBW-2-300 Light:
The CGW RY had these installed in their GP30s (circa 1963), and I remember that the serial number on the plates of the two I worked on were in the 1800 range. I noticed that the light in the photo had two different sizes of knurled knobs; I have noticed the same thing on great numbers of Mars oscillating and fixed dual sealed-beam headlights.
I have been told that the earlier Mars units had the smaller diameter knobs in plated steel, later ones being aluminum. Apparently, many were replaced with later, larger diameter aluminum ones. As you probably know, the galvanic reaction to the coupling of aluminum to copper alloys (brass) in the presence of moisture causes the nasty corrosion which leads to the breaking or twisting off of the studs... same thing happens with the Mercor/Oscitrol headlights.
Griffin Hamilton
I asked Griffin about the wiring of the dual clear Mars Lights. So far, it looks like railroads used the option of running dual clear with both bulbs on if using a single track, whereas the ones using a parallel track used a clear-red combination in order to warn of a derailment or braking emergency to another train. see Scott Whitney's comment (above)
As for your question, I can't recall seeing any Mars dual lights wired to be both white WHILE THE MOTORS WERE INTACT; oddly enough, I never ran into any of the SB-WR-2-300 units without the red lens, or provisions for same. Why this was true seems kind of odd, considering that there are so many Gyralites with dual whites. It is apparent, though, that many Gyralite users had a dual white unit in conjunction with a single red unit, whereas the roads with the Mars units relied on the one red/white combination. Maybe it was simple economics.
I did, however, see at least two F-units which had lost their motors and had the remains of the dual oscillating lights (it seems to me that they were of Mars manufacture behind the big single glass lens on the nose doors) acting as unnecessarily complex standard dual sealed beam headlights. I wish I had salvaged these units, but they are ten years in the melt.
Griffin Hamilton
The Mars SBW-2- 300 Light:
Apparently, this light was made up per the demand of railroads for a dual bulb light that could be run with both bulbs illuminated. One plate I saw was that of an SBRE-100 light with the "SBRE-100" X'd out ...... "SBW" was stamped on one side of the "SBRE-100" and "2-300" was stamped on the other side of it. This light proved to be popular on many railroads (D&RGW).
Motor of dual 300 units in Bottom
The motor in the Mars 200 Lights are located at the Top of the installed light unit, whereas the motor in the Mars 300 Lights are located at the Bottom or Top in mounted orientation. The gearbox wheels to which the linkages attach are brought into the correct orientation and the linkage length to the outer bulb plate is either increased or decreased for correct pattern.
Bottom motor mounting of lights serviced for CNW:
That is the only explanation for my recollections of having the bird's nests and assorted crud on the motors of the ones missing the roundels. I do remember for a fact that all of the ones I came across (that still had the glass) had the red roundel at the bottom of the unit.
Griffin Hamilton
There could have been revisions on newer lights for the Top motor mounting by either Mars or the RRs. The "Motor at Top" mechanism would allow a shorter rod to be used to the bulb plate, leading to increased stability (also less chance of rod ends scraping agains eccentric wheel from gearbox if not secured properly) of the linkage. Also, wiring could enter at the bottom of the case - which may be advantageous for certain setups.
___________________________________________________
Photo images on this page were taken
from compilation of Mars Light Bulletins
furnished by Trans-Lite, Inc.
