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This page last updated: December 21, 2012 as of Jan 2014

Rotary Dumper Building instructions

My Walthers Rotary Dumper had been sitting on a shelf for decades. Along came the internet access to information and companies merchandising. Searching on a working rotary dumper led me to :

Wayne Roderick, 3rd Division, PNR, NMRA (life)
1/05/99, rev 04/20/08

Homebrew Basic Stamp 2 on a Protoboard
Peter H. Anderson

Board of Education (USB) - Full Kit

Operating Rotary Dumper ... Paul Mack also makes and sells Rotary couplers! They are "customized" Kadee, so they work GREAT. Simply replace the dummy coupler with the Paul Mack rotary coupler. The other 'dummy coupler' should be replaced with an 'Accurail' dummy coupler, as the one out of the box does not work very well- at all. Kadee #5 could be used as they will mate with the customized Kadees from Paul Mack.
martyhb1 videos of his rotary dumper

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.

I knew nothing about micro controllers else i would have used an arduino.

Made many other mistakes too. and so it goes. the wheel just keeps on turning.

An overview of my Parallax BS2 control of a rotary dumper and train positioner.

A locomotive positions a unit train at the gate servo arm. Either a button on the hardwired control box or the IR remote control (from a Sony DVD) is pressed to activate the sequence. The positioner lifts its arm and moves to the rear of a car and lowers the arm to grab the coupler. The gate arm is turned to clear the track and the brake servo arm is lowered. The positioner pushes the train cars forward, then the gate is swung back against the next car and the brake arm raises to grab the leading car axle. The sequence is repeated and thus 1 car is inside the dumper. A servo lowers an arm onto the exiting car (when there is one) for security. The dumper rotates to unload the coal from the car and back to upright (a contact switch reverses the dumper). The sequence of moving a car and dumping it is continued until a light detector mounted under the tracks signals that there are no more cars to dump - a car is not over the detector when it is checked prior to the positioner moving another car in the sequence. When the sequence is complete the Siren sounds and 'Frere Jacques' or some other music plays a riff though the piezo speaker. The last hopper is not dumped automatically as the positioner has nothing to grab to push. A locomotive would couple to the string of cars and position the last car for dumping. The rotary dumper can dump the one last car without all the servo positioning.
An HO scale Walthers rotary dumper kit was used with a Parallax continuos rotation servo. The positioner has a continuos rotation servo as movement and a standard servo for the arm. An old Futaba servo is used for the car brake under the track and another at the dumper exit and a Hitec retract servo is used as the gate servo. The unit train is from Walthers and the Control box gondola is an E&C coalporter kit-bashed leftovers. The track is mostly Atlas and sundry other railroad manufacturers. The rotary couplers were made by Paul Mack. The positioner was built by me.

Rotary_Dump4everV3.bs2 is Parallax BOE BS2 and Rotary_Dump4everHB4-3.bs2 is Homebrew BS2 code. This might help or it might confuse: Rotary_BS2_Circuits.pdf.

The Walthers kit
Assembled and painted. Look close to see that the rails are not glued in place yet. They are to be located between the guide rails.
The Rotary Dumper with all covers removed. Flapper switches were used to signal when to reverse direction and stop the servo. (rather than photo diodes as planned) Step one: Rotate the Dumper can be viewed. How can i be so happy about something so cruddy looking ? The Brake is too simple to describe, so the Positioner will be the next adventure ... actually the Brake will be part of the Positioner. It will move a car into position and Brake it- hold it in position.
In the drop-in box, the rotating servo with gear and retract servo are on the table
The (Walthers) Rotary dumper i am working on. It will use Bethgon Coalgons. The rotary couplers are made by Paul Mack and the command-control will use Parallax controllers with servos and light sensors similar to Wayne Roderick's . Similar yet different, this dumper will have a horizontally adjacent train positioner to move the cars into position. The positioning will be critical as there is no room for error with the couplers connected. Subtle adjustment to the position will be made with an under car 'brake'. The coal will probably be the 'dyed in the wool walnut shells' as other bits i have tried are too heavy ( gravel, aquarium gravel, plastic beads, etc) (Painted Perlite woked for me). Now to find the shells and try them... Cabela's size is 1/32", too small to be coal... Meanwhile i will be transporting transparent coal that will fall through the bottomless pit into the invisible conveyor.
Out of the drop-in box. The controller is visible on its shelf.
The controller is visible with its rat nest of wires.
A view from the dark-far side. The controller is visible on out of the drop-in box.
Another view from the dark-far side. The controller is visible on out of the drop-in box.
Combo closeups
The wheel is against the rail while upside down. The springs are all stretched out - deformed. Stretching the springs provided the extra force needed.
R10-Rotary coupler
Rotary coupler rotating (left) while the standard coupler remains stationary (right). The center of rotation of the dumper is along the car couplers. I added that white styrene next to the rails to try to hold the car in place, -before- I stretched out the springs.
Stretched-deformed spring, car on rails closeup
Rotary-dumper-yard 2009 Dec
Rotary dumper 2010_01_12

IR Remote Codes: Normal operation is Button 1, all the other codes are to position servos when things go wrong.
1: Start_Dump_Run
2: Run 1 time
3: Rotate_Dumper Forward
4: Lower_Arm
5: Lane_Closed
6: Set_Brake +lower bar
7: Raise_Arm
8: Lane_Open
9: Lower_Brake + raise bar
0: Rotate_Dumper Back
Enter button: Do_Music_Reset
Return button: Make_Music
Clear button: Hyperspaced
Rotary dumper 2010_01_16 ... added the yellow wire hold down on the dumper exit. Actually stretching the dumper springs corrected the car off the track problems.
As built, a locomotive cannot drive through the dumper, so a DCC operation discussion is mute.

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Copyright 1991..2014 by Ivan Lee Herring