Working HO Scale Rotary Dumper

Discussion in 'Logging, Mining and Industrial Railroads' started by martyuk, Dec 15, 2009.

  1. martyuk

    martyuk New Member

    Hi there,

    I just thought that I'd put a post up to say that I'm currently building a HO scale coal layout, that works. I have a Walthers New River Mining Co. coal mine, which I've adapted to hold 'coal', and load hopper cars, and have recently been working on a project to animate a Walthers Rotary Dumper, that I managed to win on Ebay.

    I've been looking a lot for information on how to animate the rotary dumper, but there seems to be very little information out there on methods that people have used. There is a poster on one forum Pmack, who has made one work, and he makes rotary couplers out of Kadee No. 5's, which he sells - and I've ordered 6 of for my coal train. His website shows the rotary dumper, and the underside, and the workings - which was a big I couldn't seem to find anyone who's done a full write-up with pictures etc, of how they've made it work.

    I just wanted to let people know that I'm willing to do a write up, and post some pictures of how I've got it to work, if there is an interest out there about it. I also have a couple of videos of it working, and with a couple of tweaks here and there, it should be fairly reliable.

    So I'll open this up now to everyone else for ideas, comments, questions etc - and if there is interest, then I can expand on how I made it work!

    Cheers for reading this far, I was going to post a picture of the dumper, but I've just been given the error that I can't post pictures or links as I have less than 15 posts. So maybe soon...

  2. Bill Nelson

    Bill Nelson Well-Known Member


    You have undertaken an ambitious project. I remember seeing an article in either MR or MRC , about a scratch built operating rotary dumper. This was a long time ago, perhaps as much as thirty years.

    You might want to check at the NMRA library, they may have a search-able database of articles, and I think they can do reprints of articles from back issues that are sold out. It would be worth a shot, as there are some complex issues you will have to deal with to get operational.

    Bill Nelson
  3. martyuk

    martyuk New Member

    Hi Bill,

    The rotary dumper that I've got is actually operational now - I have only got a few tweaks to go and some paint to make it look proper (instead of red plastic texture!)

    And yes, I've had many challenges in making it operational - the biggest ones being making all 8 car clamps lift at the same time, and getting the dumped coal out of the tray, without it falling into the drive mechanisms!

    Thanks for the tip though - I will check it out - it could prove useful for other projects I have in mind!

  4. Bill Nelson

    Bill Nelson Well-Known Member


    Do you have a digital camera? We would love to see your progress.

    What are you using to actuate the dogs, that lock down the cars for the spin.

    We would love to see your stuff, Dr. G, Sawdust and I have been carrying this section recently, and we need another thread,


  5. Sawdust

    Sawdust Member

    YES ! Marty we need another miner on hear by all means keep posting until you get your 15 then hit us with your pictures.
  6. martyuk

    martyuk New Member

    I will keep posting, don't worry! I have some pictures of the dumper, and a couple of videos of it in operation. I've also just added cabling today to the rotary part, to carry track power, as the locomotives didn't like just picking up power on one axle...

    I've managed to keep the cables clear by having a post next to the dumper where they feed to the barrel, and have enough slack to stretch out when it rotates. works well, and I'm telling myself they look like hydraulic hoses :mrgreen:

    I've also tried to take a few pictures of the underside of the unit, now it's mounted to show how the mechanics work.

  7. martyuk

    martyuk New Member

    Oh, and Bill...

    In answer to your question...

    The kit itself had plastic cams that the dogs/clamps rode up onto to give clearance for the car to come out under. Which I was planning on using, until I found that that they didn't lift the dogs high enough for a locomotive to pass under. Which is kind of important, as the dumper is mounted on a track where the whole train passes through then rejoins the main track to head back around to the mine.

    I have found a robotics website here in the UK which does minature motors with gearboxes, and they did a linear actuator kit, complete with limit switches. I had already bought one with the idea to use it to catch the pins on the modified hoppers, in my original unloading plan, but figured with a little bit of bodging, I could make it work to lift the dogs.

    So on the top of the linear actuator (it's mounted vertically under the unit) I've built a 'H' from brass plate that I had (once again from the previous unloading plan). The brass H has 8 holes in it, which have been tapped to M4 size, then 8x M4x50mm bolts come up, which are in line with the bottom of the dogs, and thus lift them up when the actuator moves. I've also had to bodge the actuator motor, as it came with a 6v motor, and no gearing - so if the unit got a bit stuck, it had no power... so I've re-powered it with a mini-geared motor from the robotics site, with a 298:1 gearbox - and at 6v it takes about 20-30seconds to raise/lower the dogs.

    The main dumper barrel is driven by a mini-geared motor, at 360:1 - mainly for the torque - the little brute gives about 7kgcm (0.53lbft) of torque - all from a unit which is a shade over an inch long, and under 1/2 inch diameter... you'll see in the pics when I get to 15!

  8. Bill Nelson

    Bill Nelson Well-Known Member

    What fun.

    If you have a video, you can post it on you tube, and post a link here.

    Bill Nelson
  9. martyuk

    martyuk New Member

    I've uploaded 2 videos to YouTube of the dumper, and a third one of my loading facility in action, once again from when I was testing it. I'm still waiting for a couple of items to arrive, so I can finish motorising the conveyor belt, then I can test the system as a whole!

    I've tried to post the links, but the forum won't let me do that either until 15 posts... but if you go to YouTube and search for 'martyhb1' which is my username, then you'll find the videos.


  10. Bill Nelson

    Bill Nelson Well-Known Member

    interesting video, what color are you going to paint the rotary dumper? I can't wait to see this develop.

    Bill Nelson
  11. martyuk

    martyuk New Member

    I'm not sure what colour yet... The only real colour I have for painting plastics at the moment is a dark green. which I'm not sure how it would look. I don't want to paint it black, as that to me is a bit bland and too dark.

    Videos/pictures I have seen of prototypical units vary a bit - between cream, yellow, and dark~ish orange. I am open to suggestions! Sadly my painting skills aren't quite as good as my mechanical ones seem to be - so I have a feeling that whatever colour I use, that will be it, and there won't be any form of design or warning lines etc!

  12. Bill Nelson

    Bill Nelson Well-Known Member

    Marty, you are right straight black will tend to gobble up details. If I want to model black metal, I will spray paint with red auto body primer, and then over spray with flat black while the red is still wet, so the paints mix to get a rusty black look, which shows a lot more detail.

    However an expensive machine like the rotary is likely to be well maintained. If Y'all can get spray paint over there, really dark greens can be gotten similarly by spraying black (satin works nice for this, and then spraying the green over the black, which will help keep any of that oarnge from showing through.

    with that technique you need to practice on something that is not critical, and with something with moving parts work with several light coats, so ypu don't glue anything down with paint.

    Bill Nelson
  13. martyuk

    martyuk New Member


    Cheers for the tips Bill! They will be useful.... I think I'm going to have a look at some more pictures/videos of prototypical dumpers, and see if I can get any better ideas of colour. I think that even if I go with a dark green, then it won't look right. I think a lighter colour will mean that it's still noticable, and you can see the detail, but won't stand out too much on the layout... I'll put a post up with some options...
  14. martyuk

    martyuk New Member

    Well, after looking at some videos and pictures - most of the dumpers either seem to be Yellow, or Cream. with the appropriate coal dust marks. I personally think that cream is a bit too bland, so will probably go for a yellow colour... I might look at doing a quick coat of black, followed by yellow, to give it that slightly duller, well used look. I might not even have to weather it that much, as I will be using black gravel as a live load, so the dumper will get dusty.


  15. Sawdust

    Sawdust Member

    Enjoyed your video Marty. I would go with a medium color so you can see the detail & not to light to look too toyish. I like the grays & blues & maybe a 2 tone? One color on the entry & exit walls & the other on the rotary area. Here is an idea.

    Remember it's your RR & were just making suggestions.
  16. Doctor G

    Doctor G Active Member

    Very Nice!!!

    I too enjoyed your video. Very realistic. A nice way to move those "black diamonds." I am looking forward to seeing how you do with the "rotary couplers" you plan on installing in a unit coal train. I read somewhere that they really could empty a train very rapidly with this technology.

    Welcome to Zealot. We really are enjoying your modeling and this new thread.

    Doc Tom:thumb:
  17. martyuk

    martyuk New Member

    Hi guys,

    Sorry I've been away over the last couple of days, and haven't been able to reply. I've looked a lot at Pmack's pictures, and I like the colouring ideas he's used. I think I am going to go with a lighter colour for the main barrel though, and maybe add the accents with black. I'll look into that this week though. I'd like to get my whole 'system' tested first though - with the conveyors etc, before I go nuts on making it look good. That way, if I have to do any tweaks, then I can't ruin the paint job!

    Doctor G, thanks for the comment! as for rotary couplers, Pmack's website, which has been linked to already, was a big inspiration for me to actually get the project working, and he has made rotary couplers, out of Kadee No. 5's - and will make/sell them if you email him. I've bought 6 off of him, and they have turned up while I've been away!!!!! So tomorrow's job will be to install them in my hopper cars, and test the dumper, a) whilst the train is coupled, and b) whilst coupled, and with a load...

    I will post my test results tomorrow... and maybe a video or two on youtube if all goes well... watch this space!

  18. Doctor G

    Doctor G Active Member

    Hi Marty,
    Looking forward to seeing those couplers and cars and the dumper in action.

    Also Merry Christmas to you and your family there in England.

    I will be watching for the pictures and the video.

    Doc Tom:wave:
  19. martyuk

    martyuk New Member

    An update:

    I've installed the rotary couplers in 5 of my hopper cars, I will install in the 6th, once I have done a bit of work on the hopper - as it's the one I had 'converted' for bottom unloading, before I won the auction for the Rotary. I'll get a couple of pics of the coupler on it's own - and a couple of them on the hopper cars.

    I've done a quick test with a coupled train and the dumper, and all seems to work - just a couple of little niggles with one or two of the cars. Also, getting the locomotive to run slow enough to move the cars forward through the dumper was a bit difficult - I've got a new DCC controller turning up soon, which may help - but I also got side-tracked into cleaning the wheels on the loco's and also the tracks through, and surrounding the dumper, for optimal pickup.

    Because of the slight side-track, I don't have a video of the process - yet. I will endeavor to get one tomorrow - hopefully with a live load aswell.

    On the colour/paint scheme... I bought an airbrush today, and some paint - so will be testing out on a disused piece of wood before I go crazy on the dumper! But I've decided on Matt yellow for most of the dumper itself, and Matt Black, for the interior of the dumper where the rails are, and also the tray under the dumper will also get a quick coat, to make it look like a pit.

    I figure that if I find the yellow too bright, then I'll dull it down a bit with a drop or two of black paint, before application. I think it will look properly mechanical then, but so you can still see the detail, and have a bit of contrast from the black interior.

    Thank you also for the Christmas wishes, and I also wish you all a Merry Christmas and Happy New Year!!

  20. Bill Nelson

    Bill Nelson Well-Known Member

    DCC is a black art for me. very many interesting possibilities, especially sound, but I have a lot of small engines and 8.5% grades. all the room in many of my favorite locomotives that might fit DCC stuff is filled up with lead for traction.

    However I have learned some stuff @t the club where DCC has infected the standard gauge. If you get into the CV's you can play with speed settings that might slow the locomotive down.

    Another approach would be to get a super slow switcher. I have massive gear reduction built into several shays that makes them painfull for those who don't appreciate slow. I once had a 4-4-0 I had a gear reduction motor in temporarily. It was so slow that if I opened the throttle from 0 volts to 12 volts, and then closed it as fast as I could, I could get 1/4 of a revolution of the drivers.

    Eanrst manufacturing (sp?) used to make gear reduction kits for Atheren locomotives, that gave them impressive slow speed characteristics. Some of the guys at the club get really impatient with slow locomotives, but they really help make the layout feel larger, as well as giving the operator much better control while switching. As I often point out, "Hey it is a hobby; the whole point is to waste time." They don't get it, and take Shay #32 off the track to switch the mine with the road locomotive, saying it is slow. It is not, they just haven't driven shay #8 or Shay #15. they are slow.

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