Mechanizing a Walthers Rotary Dumper

[IronBeltKen]

I'm definitely not the first to attempt this - several others have successfully motorized the Walthers dumper and have the Youtube videos to prove it. Of course, all the ones I've seen up to now seem to be for the 1990's and later, where unit trains of identical-length Bethgons [equipped with with rotating couplers] are used - this allows the cars to be dumped without being disconnected from the train, enabling total hands-free operation. My era (1969-72) pre-dates that; my coal trains consist of standard 70-ton 3-bay hopper cars built in the late 1930's thru early 1950's, so my operation can never be 100% hands-free. I'm referring to uncoupling the cars from the train, and locking them onto the dumper so that only the coal falls out during the tipping process.

Over the past 18 years, I've believed I would have to do major surgery on the mill scenery if I ever wanted to make that thing rotate hands-free, so I kept deferring the idea. Fast-forward to late January: I was putting some boxes under the layout in proximity to the dumper, and this time the area beneath it didn't seem as congested as it had before. I started envisioning ways I could fit a set of dowels below the layout surface to support it. And I also discovered that the layout surface immediately past the 'exit' end of the dumper was an 18"x10" plank held down by wood screws; this wouldn't require massive amounts of cutting to remove, just undo the screws and lift it out.

Knowing that mechanizing the dumper was doable, I started trying to figure out ways to spin the supporting dowels that would make the structure rotate. During a phone conversation with my friend Keith, I learned of an incredibly simple approach: Rather than trying to use a set of gears so a motor could spin both dowels, I could just acquire two cheap identical motors with reduction gears already installed, one for each dowel. I would cover the dowels with neoprene rubber hose, and also use that to connect each motor shaft to a dowel. I perused several candidate motors on Amazon, noted their top rotation speeds, then did the math to determine the target RPM range.

I wound up getting a pair of these guys:
https://www.amazon.com/BQLZR-Gear-Box-Stabilivolt-Electric-Replacement/dp/B00HDDXBEY/ref=asc_df_B00HDDXBEY/?tag=hyprod-20&linkCode=df0&hvadid=312106042452&hvpos=&hvnetw=g&hvrand=307760750817765631&hvpone=&hvptwo=&hvqmt=&hvdev=m&hvdvcmdl=&hvlocint=&hvlocphy=9051899&hvtargid=pla-492604452120&psc=1&tag=&ref=&adgrpid=62821668875&hvpone=&hvptwo=&hvadid=312106042452&hvpos=&hvnetw=g&hvrand=307760750817765631&hvqmt=&hvdev=m&hvdvcmdl=&hvlocint=&hvlocphy=9051899&hvtargid=pla-492604452120

They were $16 apiece, rated for 12 volts, with a no-load rotation speed of 25 RPM. A trip to the nearest Home Depot for some 5/16" diameter dowels dowels, Advance Auto Parts for the neoprene fuel hose material (5/16" inside diameter), and some 1/4" thick plywood pieces from the scrap box - I now had all the raw materials necessary to build a drive mechanism.

Here is what I eventually kluged together:

I added some neoprene over the dowels, then tested it out by connecting it to an old MRC Tech II power pack.

I shot a 36-second video of the test using my cell phone [sorry about the shaky image, didn't have a tripod]. The forum software doesn't let me directly embed it in the message - so to view it you'll have to click this link: http://ironbelt.net/images/DumperFirstTrialRun.mp4

I used a solid pseudo-load of "coal" for the test in order to avoid spilling Black Beauty sand all over the workbench.

...and that is all I have time to type-in tonight! My next post will describe the process of making it fit under the layout.

 

[TLOC]

I'm definitely not the first to attempt this - several others have successfully motorized the Walthers dumper and have the Youtube videos to prove it. Of course, all the ones I've seen up to now seem to be for the 1990's and later, where unit trains of identical-length Bethgons [equipped with with rotating couplers] are used - this allows the cars to be dumped without being disconnected from the train, enabling total hands-free operation. My era (1969-72) pre-dates that; my coal trains consist of standard 70-ton 3-bay hopper cars built in the late 1930's thru early 1950's, so my operation can never be 100% hands-free. I'm referring to uncoupling the cars from the train, and locking them onto the dumper so that only the coal falls out during the tipping process.

Over the past 18 years, I've believed I would have to do major surgery on the mill scenery if I ever wanted to make that thing rotate hands-free, so I kept deferring the idea. Fast-forward to late January: I was putting some boxes under the layout in proximity to the dumper, and this time the area beneath it didn't seem as congested as it had before. I started envisioning ways I could fit a set of dowels below the layout surface to support it. And I also discovered that the layout surface immediately past the 'exit' end of the dumper was an 18"x10" plank held down by wood screws; this wouldn't require massive amounts of cutting to remove, just undo the screws and lift it out.

Knowing that mechanizing the dumper was doable, I started trying to figure out ways to spin the supporting dowels that would make the structure rotate. During a phone conversation with my friend Keith, I learned of an incredibly simple approach: Rather than trying to use a set of gears so a motor could spin both dowels, I could just acquire two cheap identical motors with reduction gears already installed, one for each dowel. I would cover the dowels with neoprene rubber hose, and also use that to connect each motor shaft to a dowel. I perused several candidate motors on Amazon, noted their top rotation speeds, then did the math to determine the target RPM range.

I wound up getting a pair of these guys:
https://www.amazon.com/BQLZR-Gear-Box-Stabilivolt-Electric-Replacement/dp/B00HDDXBEY/ref=asc_df_B00HDDXBEY/?tag=hyprod-20&linkCode=df0&hvadid=312106042452&hvpos=&hvnetw=g&hvrand=307760750817765631&hvpone=&hvptwo=&hvqmt=&hvdev=m&hvdvcmdl=&hvlocint=&hvlocphy=9051899&hvtargid=pla-492604452120&psc=1&tag=&ref=&adgrpid=62821668875&hvpone=&hvptwo=&hvadid=312106042452&hvpos=&hvnetw=g&hvrand=307760750817765631&hvqmt=&hvdev=m&hvdvcmdl=&hvlocint=&hvlocphy=9051899&hvtargid=pla-492604452120

They were $16 apiece, rated for 12 volts, with a no-load rotation speed of 25 RPM. A trip to the nearest Home Depot for some 5/16" diameter dowels dowels, Advance Auto Parts for the neoprene fuel hose material (5/16" inside diameter), and some 1/4" thick plywood pieces from the scrap box - I now had all the raw materials necessary to build a drive mechanism.

Here is what I eventually kluged together:
View attachment 142261

I added some neoprene over the dowels, then tested it out by connecting it to an old MRC Tech II power pack.

I shot a 36-second video of the test using my cell phone [sorry about the shaky image, didn't have a tripod]. The forum software doesn't let me directly embed it in the message - so to view it you'll have to click this link: http://ironbelt.net/images/DumperFirstTrialRun.mp4

I used a solid pseudo-load of "coal" for the test in order to avoid spilling Black Beauty sand all over the workbench.

...and that is all I have time to type-in tonight! My next post will describe the process of making it fit under the layout.

I also have thought of making my dumper automated. It is still in the box

Great project and thanks for sharing

TomO

 

[kjd]

I'm one of those with dumper videos on YouTube. Not the Walthers one though, I couldn't get it to work with "coal". Did you remove the cast gear teeth? How will you actuate the clamps? It looks like it will work very similar to my scratchbuilt dumper. To help it roll and stay in place, I made mine as heavy as possible, it ended up about 28oz vs 5 for the Walthers.

 

[IronBeltKen]

I'm one of those with dumper videos on YouTube. Not the Walthers one though, I couldn't get it to work with "coal". Did you remove the cast gear teeth? How will you actuate the clamps? It looks like it will work very similar to my scratchbuilt dumper. To help it roll and stay in place, I made mine as heavy as possible, it ended up about 28oz vs 5 for the Walthers.

Hi Paul, I suspected you might end up joining the conversation!

Q: Did you remove the cast gear teeth?
It was so long ago that I assembled the kit, I can't remember all the details about which parts I left out and/or cut off. I never intended to buy the Walthers motorizing kit for it because using plastic gears seemed like a very unreliable approach. I cut off some additional stuff for this project, I'll explain that in more detail in the next "blog" post.

Q: How will you actuate the clamps?
That's one of the weaknesses of my rig that prevents it from being operated totally hands-free. In my engineering-challenged mind, mechanizing the clamps would have increased the complexity by a whole 'nother order of magnitude! I find it much easier just to slide two skewers between the hopper car and the side of the dumper, these do a pretty good job of holding the car in place when turned upside-down.

It looks like it will work very similar to my scratchbuilt dumper.
LOL, I can only wish that were the case! Maybe the rotation part, yes...but definitely none of the other features that your machine has on it!

 

[IronBeltKen]

I also have thought of making my dumper automated. It is still in the box

Great project and thanks for sharing

TomO

My pleasure Tom, hopefully you can avoid some of the pitfalls I encountered.

 

[D&J RailRoad]

are you going to put rotary couplers on the cars or just separate them as they go into the dumper?

 

[IronBeltKen]

are you going to put rotary couplers on the cars or just separate them as they go into the dumper?

Separate them; I don't think rotary coupler technology came about until the later 1970's[?]

 

[IronBeltKen]

I forgot to mention in my opening post, there were 3 primary phases associated with this project: (1) Designing and building the drive mechanism; (2) fitting the completed mechanism into the target location and getting it properly aligned; and (3) installing the permanent control circuitry & wiring. Yesterday I discussed the first phase, tonight I'll begin focusing on the second.

I discovered early on that the target space was not as large as it originally appeared, for a few reasons. First of all, the dowels supporting dumper needed to be closer to the layout surface to be sufficiently far apart to keep it stable. Also, I hadn't accounted for the size or shape of the motors, which I thought were not going to be inline with the dowels but positioned further down.

The first obstacle I found was a random 2x4 occupying the space where one one the dowels was supposed to sit:

Luckily, I found that what was directly above offending plank was an 18"x 10" piece of 3/4"-thick plywood, attached by wood screws to the underlying frame. And the 2x4 in question was not structurally critical; i.e. removing part of it would not weaken the surrounding benchwork. A Sawzall made quick work of cutting off the unwanted end, but there was a wood screw holding the cutoff piece to the underlying board that had its screwdriver slots stripped, i.e., it couldn't be gripped and turned by a screwdriver; it had to be cut. A hacksaw wouldn't fit down in that tight space, so I had to remove the blade and push it by hand between the two planks until it finally was severed.

I later discovered that the opposite side of the pit also had a clearance issue of its own: Nestled ~2 inches back was another underlying board...

...this meant that I would be unable to fit the drive motors in that space like I originally planned. Trying to carve away that underlying board would require ripping up track and doing major surgery on that area of the layout. I decided to position the motors on the opposite side, which could be done if I cut away more of the underlying wood from where the already-removed 18x10-inch board had been covering.

I also cut away a few more inches from the original 2x4 the I had shortened earlier; this gave me exactly the amount of space I needed for positioning the drive motors.

The unpowered ends of the dowels fit quite easily into the 2-inch recessed space on the opposite side of the dumper pit. Now I had to begin the trial-and-error process of precisely aligning the dumper with the entry and exit tracks. Since I couldn't be both above and below the layout surface at the same time, I had to crawl out to examine the alignment from above....and if it was off by a few fractions of an inch, I'd have to crawl back underneath and reposition the end piece by what I could only guess was the correct amount. I had to repeat this under-and-over exercise several times for each end before the dumper was properly aligned.

One more thing I needed to do was to cut off the bottom half of the dumper platform "sleeve" that contained the round slots originally supporting the dumper. The magenta line is where the cut was made, and the bright green dotted line shows where the dumper's end discs sat in:

This enabled me to slide the platform sleeve back into the dumper pit opening.

That's all for tonight, will continue tomorrow evening...

[EDIT] I meant to include this pic of the dumper inside the re-inserted platform sleeve last night, but I was tired and I totally forgot...oops:

 

[kjd]

I wouldn't miss it, Ken! Let's roll coal (cars)!

 

[IronBeltKen]

In my Tuesday post, I mentioned how I encountered all these previously-hidden obstacles and what I did to work around them. One of those actions was to reverse which end the motors would reside in - beneath the exit track and not the entry track. That introduced a new problem that required a bit of extra labor to resolve.

You may or may not remember me talking about an 18" by 10", 3/4-inch thickness board that I removed by undoing a few wood screws, to gain access to the underlying framework. When I tried putting it back in place, this was the result:

The motors were occupying much of the space where the plank originally had been, with the end result that the exit track wouldn't line up vertically. I got a few measurements and, luckily a friend of mine had a spare piece of 7/16" thick plywood from which I was able to cut a 6"x7" piece to lay over what remained of the 'amputated' 2x4 and 1/2 of motors; the remainder would require an 8"x7" sheet of 1/16"-thick styrene, to make the covering line up evenly with the surrounding surfaces:

What was still missing at this point was the exit track roadbed, I had to break out my stash of Scultamold to reproduce it:

I still haven't painted and scenicked this area, I'll get around to that once I've finished everything else associated with this project...

 

[IronBeltKen]

Up to now I've covered Phase 1, the design and building of the dumper drive mechanism, and Phase 2, installing and aligning the mechanism with the entry and exit tracks. Now we're on Phase 3, installing the permanent controls and wiring.

All during the first two phases, this is what I used to control the speed and direction of rotation:

The old MRC Tech II did that job very well, but it looked kind of 'haphazard', like something Red Green would do if he did model trains. Not me - I wanted something built-in and not so easily noticed. This presented a challenge, because I'm not an electrical engineer; I didn't know exactly what type of rheostat - with what ohms range - I would need to buy in order to make this contraption work. (That led me to initiate this other thread...)

My friend Terry (a.k.a. bnsf971) pointed me in the right direction with a number of Amazon links to rheostats and potentiometers that might fulfill the need. In addition to wanting something specifically designed for DC applications, two important features I was looking for were (1) ability to completely cut power to the motors past the lowest speed, and (2) simplicity of wiring: two wires in --> two wires out. I didn't want to be forced to read a schematic diagram to figure out where to connect a third wire. After reading a number of customer reviews, I settled on this ALEDECO PWM Low Voltage DC 12V 2A motor speed controller since it appeared to have all the features I needed and was very reasonably priced. To hedge my bets I also ordered a second one - just in case the first one might turn out to be a lemon. (It was not)

It was a great little device, once I figured out the correct input polarity after a bit of trial and error - there were no "+" or "-" markings by the connections. I needed to fasten it onto a piece of scrap wood to make the knob perpendicular to the fascia:

Next, I would need to connect the output wires to a switch to reverse the polarity for direction of spin. A local friend had this DPDT switch in his scrapbox:

After drilling a few properly-sized holes in the fascia, the switch and rheostat fitted right into it:

Finally, I needed to run a pair of wires 17ft from an existing 12V wall wart on the main power strip, to the inputs on the rheostat. Once I had finished stringing the wires under the benchwork, I discovered - as soon as I tried to insert the wire ends into the rheostat input terminals - that the extremely tight clearances on the back of the fascia made it impossible to do that without removing both the rheostat and the switch all the way back out of the fascia! A minor PITA that cost me another 15 minutes of delay before I could test-drive the dumper with the new controls.

A few days later I discovered that I'd forgotten to permanently attach the end frames of the drive mechanism to the benchwork. I had used large hand clamps to hold on each end piece, since those made it easier for me to calibrate their positions to get optimal alignment with the entry and exit tracks. When I tried to replace these with 'C' clamps, I was going by 'feel' rather than looking directly at the end piece with the motors on it; so when I finished tightening the 'C' clamp and pulled away the hand clamp, the motor end dropped down 1/2"...oh joy, now I got to repeat the whole under-and-out exercises to get the end piece re-aligned with the exit track! Once that was finally done, I fastened the end pieces with drywall screws for a truly permanent fix. (Another hour of precious and scarce free time wasted thanks to my short-sightedness...)

The project wasn't truly finished until I got the miniature table with the coal-catching basin back into its regular spot beneath the dumper:

...and now, on to the cleanup and de-cluttering of the trainroom!

 

[kjd]

Good job, Ken. I like the simplicity, will we see a video of it doing it's thing? Is the barrel of the dumper held in place with gravity?

 

[bklynman01]

I've had a lot of fun watching this thread. I don't have a place for coal dumps, but the lessons learned can be applied to many places, and I appreciate you including those tidbits of information. One thing I did not remotely think of was where the coal was being dumped. That last post about the catch bin made me say "HA" out loud at myself.

Very nice work. Looks like something that you will enjoy operating for a long time.

 

[IronBeltKen]

Good job, Ken. I like the simplicity, will we see a video of it doing it's thing? Is the barrel of the dumper held in place with gravity?

Thanks Paul for the kind words! Regarding the video, I don't have any way of shooting videos other than my smartphone (and you saw how that turned out, LOL!). I'm hoping maybe I can coax somebody with a tripod and video camera to stop by and get some footage, after the mess has been cleaned up.

To answer your 2nd question: Yes. I made sure to space the dowels far enough apart (~4") to keep the center of gravity low.

 

[IronBeltKen]

I've had a lot of fun watching this thread. I don't have a place for coal dumps, but the lessons learned can be applied to many places, and I appreciate you including those tidbits of information. One thing I did not remotely think of was where the coal was being dumped. That last post about the catch bin made me say "HA" out loud at myself.

Very nice work. Looks like something that you will enjoy operating for a long time.

Thanks for the feedback, glad you enjoyed it. On the topic of lessons-learned, I've had the privilege of learning from reading the stories of disasters suffered by other forum members so I could put the preventative measures in place before they happen to me. Most of my mistakes could be traced back to a single root cause: Impatience!

 

[kjd]

Ken, again, I am impressed with the simplicity of your design. I've looked at the Walthers dumper for, well my daughter turns 19 this year, so nearly two decades, trying to figure out a way to make it work with coal. My Walthers one works but still has the plastic end ring holders that happily collect the coal as its dumped and then refuse to turn. I had mentally designed new end rings and various other methods of holding in place but your solution is pretty brilliant, eliminate the problem area entirely.

The phone video wasn't that bad. To help stabilize it you could rest your hand on something the right height or tape the phone to a stick and strap the stick to a chair. Or something like that.

 

[IronBeltKen]

Was homebound today due to a late-season blizzard, so I decided to draw some diagrams after-the-fact.

The first one shows the principle of operation: Dumper body sits on neoprene-covered dowels, dowels turn, dumper body spins opposite direction.

Next is a top-down diagram of the entire drive mechanism; component descriptions are in same-color text as the objects themselves:

Notes:
1) Dumper body is depicted in red since that was the color of the plastic the Walthers kit was molded in (I repainted painted it in Grimy Black)
2) Dowels are the same diameter as the motor shafts
3) Pieces of neoprene rubber hose are used to connect the motor shafts to the dowels
4) Dumper sits upon strategically-positioned neoprene rubber hose segments covering the dowels
5) Dowels sit directly in same-sized holes on static end plate; holes on the motor-mounting end plate are larger than the diameter of neoprene hose, which is not supposed to touch the end plate. Screws attaching the motors to the plate, also serve to hold the powered ends of the
dowels in the intended position.

 

[kjd]

It's been a few months now, how is your dumper working, Ken? Is there anything you'd do different? Things you like?

 

[goscrewyourselves]

Impressive work!