EMPCCCC Rotary Dumper

EMPCCCC
This page last updated: December 21, 2012 as of January 2018

Rotary Dumper Building instructions

TL;DR : Coal dumpers need an H bridge underneath to raise and lower the clamps. Coal dumpers are made different than the wood chip dumpers as they are shorter - cut off the parts along the scored lines. I added styrene to the top of the coal cars so they can be used and have locomotives drive though instead of doing the motorized H bridge and cutting the height - they are shorter than wood chip dumpers - to fit the coal gondolas. Superglue something that has a hex screw in it to the plastic gear so the gear can be easily repositioned. Stretch out the springs so they are 'stronger' and hold the coal cars upside down.

The first version used a Basic Stamp micro controller. Complete photo coverage and instuctions - historical steps are here. Project action is demonstrated at the HO train Hobby youtube Video channel.

Walthers has re-released the Rotary Dumper. My plans on building several dumpers, using knowledge gained and an Arduino micro controller are here .

A Rotary dumper review

rotary dumper base: The base needs to hold the dumper and allow the 'coal' to fall through unimpeded... basically not have a base - just walls supporting the dumper and metal rods supporting the curved ramps that lift the clamps.

rotary dumper gears: 12 tooth Tamiya (metric 48) pinion gears Gears need to be able to turn the dumper without getting clogged from the 'coal' and not pull the dumper off its rotation. a motor-servo turning the gears. Bearings or wheels supporting the dumper in its rotation - also not to be clogged with 'coal'

Google pinion gears for information about the difference ... the metric system generally use the module system... Japanese metric are 47.5 versus inches 48 ... Whatever - Use the same types !

As of January 2013 I do not think they are really ANY Pitch. Tamiya 12 tooth are slightly Too Small. 12 tooth 32 Pitch ? would make them slightly larger than 12 tooth 48 pitch. 12 tooth Tamiya (metric 48) pinion gears : TamTech-Gear GB-01 #40502... 14 is still too small and 16 and 18 tooth are too large to fit. GEEZ if you have to, follow their instructions and/or glue the plastic gears in place. I superglued a Tamiya 12 tooth to the plastic gear and it works great. This allows easy placement and uses the plastic gear to fit with the dumper gear.

rotary dumper clamps: A rotary dumper needs a motor to move the clamps that hold down the car when rotated. The springs are too weak, a servo is too- it will 'rebound'(stretched springs Will hold the car onto the rails) The clamps need to be able to move UP high enough for a locomotive to drive through and DOWN strongly enough to actually hold the car when upside down.

As of 2012 I have decided to make the cars taller and use the standard springs - STRETCHED out. That solved many problems and will remove the hold down servos needed. 2 servos for positioner 1 for dumper rotation.

As of July 2013 I have decided to use a 'B' unit as a Remote controlled locomotive - it will move through the dumper as long as it does Not have a cab or Dynamic brakes.

As of November 2016 I have re re decided to make the cars taller. The loco locomotive looked too stupid even for me. So any locomotive can drive through and decouple after the positioner takes over moving the cars.

The elegant solution is to have a H shaped rail move up and down underneath the dumper to raise and lower the clamps. This would allow Any locomotive to drive through and still use undevoed coal cars in the dumper.

Train Positioner: a cart on rails that holds a micro servo arm, moved by wires on a pulley or a servo on the cart driving against a gear rack. Great parts source : McMaster-Carr Supply Company. As of July 2013 I have a gear driven rail from VEX Robotics.

Operating Rotary Dumper ... Paul Mack also makes and sells Rotary couplers! They are modified Kadee #5, and they work GREAT. Simply replace one dummy coupler with the rotary coupler. The other dummy coupler can be replaced with an Accurail Dummy Coupler # 109 or a Kadee #5 or modify it to fit the rotary Kadee.
Sergeant Engineering also makes rotary couplers, AFAIK they only couple with Sergeant couplers and do Not fit standard coupler pockets. Never tried them, just reading about them convinced me to use the Paul Mack version.

Note the servo and yellow wire to the right of the dumper :) It works. This makes 6 servos used to unload a coal train.
1. positioner wheel mover
2. positioner arm grabber
3. car gate arm stopper
4. car brake axle grabber
5. rotary dumper rotation
6. exit wire hold-down
One of the buttons on the BN control box is no longer connected to the controller.. the resistor wire is snipped and the pin is used for the exit servo. The wiring on the hard wired controller has become embarrassingly atrocious. hmm, spellcheck does not like the word positioner, o well, it can be found on the web.

2013: Positioner mover, grabber, dumper turner servo .. as long as they work correctly (and the springs are strong) all the others are Not needed.

Reworked the module and the drop-in dumper. Added 2 tracks in the module back area so a locomotive can go around-behind the dumper, and a box the trains would go through and the electronics and wires can sit on.. on the way to camoflage the wires and make it look industrial-ish.
After viewing videos of dumpers and positioners it seems the positioners are on the empty side of the dumper. Many things i do not know at all :) Real Coal looks a lot smaller than what i use (these days it is ground to pea size so it burns easier, no more lumps). o well i like to see the lumps and do not want little grains getting into the works (Graphite : Kadee Greasem coupler lubricant is actually coal. Peat, Lignite, Bituminous, Anthracite, Graphite. That would be itty bitty, not cause sticking problems, but it would sure be a mess:). Someday i will check out what Walnut shell gun cleaner actually looks like.

A 44 tonner can drive through the coal dumper, or a cabless slug. Anything with a cab is too big. AFAIK no one can position the cars accurately so a positioner is required - an HO scale positioner cannot push a locomotive (no neutral - the gears act as brakes) so the locomotive must be uncoupled to dump the coal. A locomotive could drive through then uncouple and have the positioner on the far side of the dumper to pull the cars. Driving a locomotive through the dumper would require the tracks to be powered... seems a lot of extra work for no real gain. I like watching the positioner do its thing... and AFAIK it is prototypical.
As of 2017 I have a positioner on the far side of the dumper and it will connect to the cars After the first car is dumped coupled to the locomotive - which will then be uncoupled for the rest of the train.

Rotary dumpers are used because the coal gets frozen and will not fall thought the hopper doors. The coal mounds up at the grates and makes unlatching the hopper doors too hazardous... too many lawsuits to argue with that.

Lessons learned
-Use support bars under clamper rails and cut out ALL the floor (well except for the back third).
-use 12 tooth Tamiya (metric 48) pinion gears to turn the dumper !NO! does not REALLY work! Superglue it to the plastic gear.
-Make the Dumper for wood chip cars and a locomotive can drive though to spot the first car, and the positioner can be on the 'empty' side of the dumper and thus pull the last car through.
-Coal cars will leave 1 car un-dumped. Dump the last car by pulling string of cars from other end with a locomotive and stopping the last car in the dumper. (Try making the hold downs Long like the wood chip, they will probably 'snap' down the last half inch... ) ... Add plastic to the top of the coal cars to make them the same height as the Wood chip cars... kinda like later model ore cars :)
-Positioner top rails act as a brake since the bottom rails are rolling the wheels... so make it carefully.
As of 2017 I make the Positioners from VEX parts.

Coal Load: 3/4 cup to overfill 1 car
Perlite weighs 18 grams per 1/4 cup :54g = 1.9oz (I spray paint it black)
White Rice weigh 22 grams per 1/4 cup :66g = 2.3 oz (Black Rice weighs ?)
Walnut shells weigh 22 grams per 1/4 cup :66g = 2.3 oz (Still crunching walnuts i bought at grocery store to get the shells, need to try the brass ammo shell cleaner type)
Plastic aquarium gravel weigh 42 grams per 1/4 cup :too heavy
Sand weighs 78 grams per 1/4 cup :too heavy

Even after soaking in paint wash and spray painting, Perlite seems to break very easily, however it is light and works ok.

10 grams = 0.351 oz
1 oz = 28.47 g

Recheck 2011sep9
measurer was 10g, subtracted from weight
8g -unpainted, sieved for big grains only
10g -unpainted, sieved for big grains only
10g -large grained mix: light paint coat
12g
14g
16g large dark
18 small grained dark
there was some variance .. over a Third!

30 fl oz plastic Miracle whip jar holds 4 cups = 5 cars [When did a quart become 30 oz?]
20 cars = 4 jars
100 cars = 20 jars

So how much can the ship hold... TBD .. estimates follow, given 1 foot of ship : 6" fore and aft are not holds - contain the conveyor etc...
a jar is 6" tall and 3.5 diameter, so make that 4" length and ship wide per 'hold' : 3 jars per foot, a resin 3' ship {258' long freighter}($295+) would hold ~ 6 jars : 30 cars
each additional 10" resin sections ($64+) ... 12..15 cars
plastic 6' ship ($389+) : 5x3=15 x5= 75 cars

As it turns out the ship will be built - not a kit. Based on a 36" conveyor that will be 9 hopper holds. Each hopper hold of the ship can hold less than 1 jar. Estimate about 8 jars so that would be 40 cars ... make it 2 20 car sections.

The rotary dumper takes about 30 seconds to dump a car, it takes a lot less time to flood load the cars, this will require a LARGE holding bin between the dumper and the flood loader. A large bin will allow dumping the cars and flood loading at a later time as doing a concurrent operation would be crazy on the flood loader side.
Even going with 20 car train sections, a 4 jar bin that is sloped and has a gate will take up a lot of room between the dumper and the flood loader - there is already a height crunch due to the dumper extending below the track level and the flood loader being about a foot tall - of the 18" distance between the 30" lower and the 48" upper tables. The conveyor between the bin and the flood loader has to angle a little and the coal does not disperse like water - it will mound up and not flow back down without some kind of applied force, thus the need for a sloped bin. See NSmodeler24 videos for examples.

As of 2017August : Plan is to overfill the bins (side hoods added) - to hold 48 cars of coal. Multi loco unit trains driven as slow as necessary to be floodloaded. OK well actually make it 24 car unit trains. Only problem is the need for another 24 cars using Paul Mack couplers and 48 cars using Glatzl and they are not made anymore.

Rotary dumper Coal 2017 8 8 Turning Perlite into HO scale coal.

Building the Rotary Dumper Coupler Info and links

Rotary Couplers are either Kadee's modified by Paul Mack- Though it seems he has retired from modifying them; or Glatzl's sold by Sergent Engineering - which are also extinct as of July 2017.

Glatzl's sold by Sergent Engineering are back in stock as of 2017August1...

and NO they are not - the link has been removed, there is no hope in the world....

Videos...