I am in the process of adding a paper mill to my layout and have picked up a few of the Walthers woodchip gondolas. In the group of kits Walthers offered for a paper mill there is a rotary dumper, which to me implies emptying woodchip gondolas. With a lot (all?) gondolas used for coal at rotary dumpers one end is painted a different color to denote where the rotary coupler is, but the woodchip cars I have aren’t painted this way. Should they be? Or are these cars handled more (uncoupling, dumping, coupling again as the next car is moved into place, etc.) during the unloading process? While I don’t plan to have an operational rotary dumper, I do want to incorporate the time for the crew working the paper mill to have to spend unloading these cars during an operation session.
Thanks!
This photo is taken from “Trains, Tracks & Tall Timber --The History, Making and Modeling of Lumber and Paper” by Matt Coleman, published in 1996 by Walthers. You can see the coupler attached to the rotating gondola. Also, the coupler is not at the center of rotation. This is proof that this is not a rotary coupler.
The book also shows a diorama plan for the paper mill facility.
Awesome picture, thank you! I also have the book on the way through Amazon. This will slow down my operator for the paper mill considerably!
Not all paper mills used rotary dumpers, and not all woodchip gondolas were used with rotary dumpers. At least from 1he 1930’s on, regardless of loads handled, woodchips, sand, coal, whatever, were used only, as far as I know, with gondolas with rotary dumpoers. If your model railroad is freelance, with your own road name and reporting marks, by all means assume the cars have rotary couplerws and paint the ends differently. Otherwise, by all means follow the prototype of the railroad and time-periiod you are modeling. Hope to see yoiur posted photos of your modeling.
So there were instances of rotary dumpers designed for dumping individual cars (since this example is exclusively for regular cars and not rotary ones)… 
Interesting. I would assume these were more common for smaller applications? Seems like it would be less economical to have to split the train at every car to dump them with longer train lengths, rather than the rotary coupled versions.
I’m guessing rotary couplers did not come into general use until the unit train era. In the classic days, wood chip and other bulk gondolas were mixed in with general freight cars, whereas unit trains must have their rotary couplers mated with standard couplers exactly in order to prevent twisting off couplers.
I believe there are three ways to unload a wood chip gondola. This is from looking at books on GN and NP, the predecessors of BN.
The 1950s method was a conversion from a drop-bottom gondola.
Page 106 of “NP Color Guide to Freight and Passenger Equipment” by Todd Sullivan 1995
The 1960s method was end dumping, which initially only had A-end, later both ends, and the same facility could also be used for trucks.
Page 73 of “Great Northern Equipment Color Pictorial Book Two” by Scott R. Thompson 1996
The 1970s method was the rotary dumper that we all know about.
I’m not sure, so I’d appreciate it if you could point me to some sources.
We’re not talking “unit train” operations here. At most you’re dealing with maybe a dozen chip cars.
Uncoupling the car for the rotary dumper is still WAAY more efficient than any sort of non-rotary style unloading, whether opening (and then reclosing) bottom doors, or digging out the chips with mechanical equipment.
Keep in mind lots of these ‘rotary dumpers’ are more like the old ‘car shakers’ than the machines used for coal-gin consists, they just roll the car on its side far enough for the contents to drop into a hopper.
These could easily be arranged for gravity feed using an inclined dumper and spring switch to tail track. ‘Bailey car’ arrangement would lift the cars up to the approach…
Wouldnt Rotary Couplers be more expensive to manufacture?
I thought Woodchip Gondolas were coupled and uncoupled evey time to empty or were equipped with Bays like Hopper Cars are to empty them out with needing to rotate them
What’s expensive with rotary couplers is building a dumper big enough to rotate the car along the centerline of the draft gear. The ‘cylinder’ has to be much bigger…
That makes sense for unit trains at large scale. For 10-car blocks, hopper-style dumps or car tippers are better.
Here’s a video with details of one unit system:
That makes sense on how they work, but I’m still wondering, do they uncouple and re-couple the cars after each rotation?
No; that’s the whole point of rotary couplers.
The more interesting question is how you arrange brake lines on ‘rotary’ cars so that they handle the rotation but do not drag close to the track…
Ah, makes sense now!
Thanks, Woke!
Perhaps some sort of retraction mechanism to allow the hoses to extend just long enough when dumping?
Except the point is that chip cars don’t have rotary couplers. Unit-train cars like coal gondolas do.
We’ve bent over backward to establish that chip cars don’t have rotary couplers.