The following photos by:
Scott J. Whitney
Mars RE-12 Light on private car - Caritas
Scott found a plate on the Mars Light that read:
PORTABLE RE-12
SERIAL NO. 5877
Descripton of mechanism by:
George Hickok
The lamp & reflector are mounted on a two axis gimbal system, which gives independent freedom of movement in both the horizontal and vertical planes. The inner most ring of this system is used to mount the reflector and lamp socket. The lamp socket is connected using welding cable, or other wire that is very large in size and made with the finest possible strands. The constant flexing will limit the life of these wire leads. (The load from the lamp is about 8 amps. The wire is I think # 6 AWG, which would be good for about 60 amps or so.)
The drive system consists of a motor and gearcase which drives two cranks. (The cranks as I recall rotate in opposite directions.) These are connected via links with ball bearing swivels to the horizontal and vertical gimbals. The gear ratio and offset of the cranks is such that the beam of the lamp moves in the characteristic flat figure eight motion. There is a dome shaped lens on the front of the unit, which is colored deep red.
The whole assembly is very well built. Everything is very heavy duty, and all the motion points are ball bearing. Although things don't move very much, it's clear this thing was built for the long haul. The base 'can' and all of the trimmings are cast aluminum, and yet the whole thing is so heavy that one person can just barely manage to move it around. That is in part why I don't use it much: it's hard to move around, as well as being bulky.
The drive consists of a small DC electric motor, mounted on the end of the gearcase. A single reduction worm gear is used to transmit motion to the first crank, which provides the vertical axis motion. A single reduction spur gear is used to drive the second crank, in a 2:1 reduction, which drives the horizontal axis.
The gymbol rings are connected to the cranks using aircraft style bell cranks at each end of the linkage. The motor is ball bearing, the two gear shafts are plain bearing, lubricated by grease packed around the gears. The length of the linkage is adjustable allowing the motion to be centered both horizontally and vertically.
The lamp is a 32 volt, 250 watt locomotive headlamp bulb. (This happens to be the same lamp that the 4449 and 700 use for their headlights.) This is a typical projection style lamp, with a very dense filament assembly intended to concentrate the light source in as small an area as practical. The lamp is manufactured to maintain the filament position fixed relative to the base of the lamp, so that the focus remains consistent when a new lamp is installed.
Although the red lens filters out much of the non-red light from the lamp, the output is still very bright, and has been described as being like a lighthouse on the end of the train.
The linkages in the RE-12 are located at the TOP of the light unit. A 32-volt motor is used (on unit illustrated below) with the standard gearbox found on many other of the Mars Lights (R-250, SB-R-250, SB-WR-2-200, WR-5000, and possibly others).
The following information and photos by:
Gary Riccio
The following photos illustrate the portable Mars RE-12 Light that was permanently mounted to ACL office car 303 and that the city of Rocky Mount, NC is now restoring. The ACL made it mandatory to have an oscillating light on the end of all passenger trains. There were a lot of portable lights around - so they made use of them.
