This Car Exceeds Plate F

[CandOforprogress2]

Reefers like the Produce Xpress exceed plate F. Not many places left these days where Plate F cant travel

[RME]

CandOforprogress2

Articulated Hopper Car? Why God Why?!

Because these weren't as good a way to get to corresponding capacity:

and the Rail Whale approach with span-bolstered double three-piece trucks at each end is overkill for coal gons and not very practical for hoppers that must bottom-dump effectively.

The Beth Steel articulated hopper (the lower picture) is actually a comparatively late development (circa 1968).  It distributes the load better across the axles and guides better than a battleship-gon design with the truck pivots at the quarter points, and has no difficulty being rigged for clean bottom dump.  I would not have been surprised to see this idea developed for unit train service after the manner of the FuelFoiler ten-packs, and perhaps five-unit stack-train sets, where continuous dumping and not rotaries were the preferred unloading method.

Strong need for articulation went away when large aluminum bathtub gons became practical, and of course rotary dumping (for coal) became essentially de rigueur.  And then the light tare weight construction was applied to sets of bottom-dump hoppers at 'normal' length and truck arrangement, letting railroads standardize on bearings, sideframes, etc. instead of needing proprietary and relatively unproven arrangements ... like those on the light-aircraft-built articulated hoppers Southern tried earlier in the '60s.

I believe NDG and some others have mentioned the specific rationale behind the Canadian articulated covered hoppers, and I'll leave the detail discussion to them.  Again, the arrangement gives better distribution of loaded weight and better tracking, and this is especially valuable on light rail or track with severe grades and curvature.

[RME]

Paul_D_North_Jr

... some kind of electrical set-up (Fig. 8), which is described as:

"FIG. 8 is a schematic diagram of the electrical circuitry in each power package responsive to relatively low voltage command signals from the preceding power package for transmitting relatively high-voltage command signals to the next power package;"

There's nothing really mysterious about this: if I understand correctly, and I think I do, this is 'standard procedure' for transmission of analog signals over long distances in a relatively (electrically) noisy environment.

The command signals -- think of them as a fancy kind of MU signal -- need to be passed down the length of a distributed-power consist; assume for a moment that it is rigged similar to a HPIT train with 20 platforms or frames or wells or whatever between power packages.  So it is amplified up to considerable voltage, much more than needed to overcome 'normal' resistance in the wiring run down the cars (and probably cleaned up and reshaped somewhat, at least if I were doing it).

By the time that signal gets to the 'next' power package, it will not be at its origin voltage, and may have a variety of imposed noise.  So we need circuitry that, regardless of incident voltage, generates the desired analog modulation carried in the 'command signals', opto-isolates and filters it as needed, and then clamps the voltage to appropriate levels and passes the signals to the components in the receiving power package.

The actuators and controllers on this power package were probably built to use comparatively low voltage (industrial DC?) and this needs to be amplified up again for transmission down the trainline.  In my opinion, it may make sense to take all the transmitted signals and 'normalize' them in voltage and waveform at this point, including those that are being passed through the power package without 'commanding' anything (such as ECP brake control).

This was in the era before digital communications became cheap and well-supported in industrial-control applications, but here, too, amplifying something like a PCM signal for transmission and then clamping it on reception is a sensible approach.  We now have a long experience with practical CNC, so this stuff is obvious -- I suspect it was not obvious in the mid-Sixties, in railroading.

[Paul_D_North_Jr]

RME, thanks for your thorough and technical explanation, but I confess I comprehend only about 1/3 of it - which is why I wasn't too sure about Fig. 8.  From John's writings I've discerned the intent and purpose of this, but little about the 'nuts and bolts' of it.  Maybe when I retire and have mnre time to learn about such things . . . 

- PDN.