What the heck is a "Robot Car"?

[bpickering]

I was reading Greg McDonnell's "U-boats" this morning (trying to convince myself that I should be getting ready for work...), when I noticed a picture with a caption that caught my eye.

One picture showed what the author termed a "Robot Car" sandwiched between the four locos pulling a fairly long train.
{loco} {loco} {Robot car} {loco} {loco} {train.........}
I assume it's some kind of instrumentation, but was wondering what specifically they might be measuring with it in this location?

I'm aware of a dynamometer car, but my impression was that such would be coupled between ALL the motive power and the train, not in between the engines. Likewise, I could imagine a need to observe the performance of an individual locomotive, but I would suspect that said loco would need to be the only one in front of the instrumentation, or some other way in which you could isolate the forces exerted by the one loco (speaking as an ex-physics professor here, not a railroad engineer... please be gentle if I ignored something well-known. [:)])

Brian Pickering

(If people need chapter/verse of the reference to provide an answer, I can get that tonight. Right now, I'm on lunch break at the office....)

[ahuffman]

I suspect what is being referred to as a "robot car" is a car equipped with the radio control equipment for remote control of a mid-train or end-of-train helper set. Southern and probably other railroads had cars set up to carry this equipment and connect via the MU cables to the locomotives that werre being controlled. I think (maybe someone can confirm this) that there was also a system in use that responded to strain-gauge measurements of the drawbar load and air line pressures to determine what mid-train helpers should be doing. As I recall, the Southern had both boxcars and old F units fitted up for this purpose.

[ndbprr]

Not having seen the picture you reference I can only speculate but do have a fairly good explanation (I think). Back in the late 60's many railroads experimented with distributing the power at multiple points throughout a train. the thinking was if you could place the ppwer at the right location you could minimize forces on the drawbars and knuckles thus pulling longer trains more smoothly and with less slack action. This practice was tried by nearly every class one that had a mountain grade. Standard practive was to convert an F unit - usually a B unit into a remote control radio operated slave and attach it to a couple of engines. these were then placed about a third of the way back in the train and additional helpers were placed on the rear breaking the train into one third segments for each set of power. It would seem you saw a variant of this and the front end power and the slave set were coupled together for some reason.

[GDRMCo]

Here in aus Queensland Rail uses what we call pie carts. mostly they are almost 20' flat cars with a bg box of equipment. Instead of remote controlling the locomotives from the lead units (these cars are hooked up to the mid train helper set) these car sense the pressure and stuff on the drawbar and adjust the speed or activate the brakes accordingly. But soon these cars will be all gone as the locomotives go through rebuild and radio control equipment is installed.

[bpickering]

I'll see what I can do this evening about getting a small picture up. So far, ahuffman has hit one, perhaps two, nails on the head- the Robot Car appeared to be a converted boxcar, and it MAY have been on Southern (note the conditional- until I can go home, all system memory in my head is dedicated to work, and I might be just willing/editing that vague image in my memory to match!!!!!)

Brian Pickering