3D Printed Rotary Car Dumper aka Tippler

[Marbelup]

I have uploaded a video to YouTube of my latest creation - a rotary car dumper or tippler.

All of the mechanical parts have been printed at home on a Makerbot Replicator using Colorfabb PLA/PHA blend filament, which I have found works better than pure PLA (or ABS) for printing larger parts without warping.

My initial intent was to make a very simple, hand-operated dumper to test some ideas I had for rotary couplings. However, over the course of a couple of weeks, it morphed into a fully automated device including car positioner.

My first attempt at making a rotating housing for Kadee couplers looked promising but the Kadee couplers tended to uncouple when rotated. The rotary couplers shown in the video are a somewhat unorthodox design, also 3D printed on the Makerbot, which were designed to fit my existing wagons without modifications, in place of Kadees. I am currently converting over to ready-made HO scale rotary couplers from Sergent in the US, which will fit my wagons with minor modifications.

The wagons are Sn3.5 scale, which is my main modelling scale, and were 3D printed some time ago by i.Materialise in Prime Gray. The prototype wagons were bottom discharge but they are useful for testing the dumper as I have a rake of 11 of them. The dumper will also potentially handle HO wagons or S scale standard gauge wagons with minor modifications. As with real rotary dumpers, it has to be made to suit a particular wagon design with regards to wagon dimensions and coupler height. The end plates are separate from the horizontal parts of the "barrel" so parts can be mixed and matched to vary the length. The "grippers" which hold the wagon in position can also be varied to suit the wagon design.

I am also working on 3D designs for a couple of types of iron ore wagons as used in the Pilbara region of Western Australia. Designing these wagons was the impetus for investigating rotary couplers, as the major iron ore producers in the Pilbara all use rotary dumpers in their operations. Some of the real dumpers handle 2 wagons at a time which should also be possible with my model.

 

[Enterprisingwestern]

Only one word for this, absolutely brilliant!!

Well done.

 

Mike.

[jonhall]

I think that's great, but why tip bottom discharge hoppers? Presumably that's what the prototype does, but the question remains why do they?

 

Jon

[Marbelup]

The prototype hoppers were not tipped. I only used the bottom discharge hoppers as a test for the rotary dumper because I had a rake of them already. The model hoppers were also compatible, in terms of their length, with some other wagons which may be modelled in the future.

[eldavo]

Very impressive.

 

Cheers

Dave

[Arthur]

It's not unknown, here's an ore hopper being tippled on the Skinningrove iron works tippler. The device was used to unload ore, coke and limestone in whatever wagons they arrived in.

 

http://www.image-archive.org.uk/?p=4772

 

You get a 'cleaner' tip by tippling. Materials, especially if wet and sticky or large and lumpy, are less likely to stick if tippled rather than run out of hopper doors so it's an effective way of emptying any wagon.

 

Some steelworks only had tippler facilities, especially in the post war years, so they could only empty wagons that way but they could handle any wagon.

 

There used to be a clip on YouTube of hoppers being unloaded by tippler at Llanwern in the 1960's though I cannot now find it.

[mgbusa]

I also believe it has to do with speed. It take only few seconds to unload a hopper with a rotary dumper.

[69843]

There is no other description for this apart from pure genius. Congratulations on a fantastic innovation Richard

[lyneux]

That's awesome Richard! One of my un-built layout plans dreams is to build an iron ore tippler using my PTA wagons and sergeant rotary couplings.

 

Can you tell us more about the control mechanism of the wagon positioner and rotator? It looks like a good project for an Arduino or Raspberry Pi?

 

Guy

[Fat Controller]

I think that's great, but why tip bottom discharge hoppers? Presumably that's what the prototype does, but the question remains why do they?

 

Jon

The one at BSC Landore discharged 'flat-bottomed' minerals by tippling, but hoppers were simply discharged into the space between the rails.

NCB operations often used to tipple all wagons, especially if the load was 'claggy' bits of spoil.

[Marbelup]

In answer to Guy's question, I am using a Picaxe Shield AXE401 microcontroller based on the Arduino form factor.

The Picaxe is programmable in BASIC which I find easier than C. Granted, the Picaxe is not as speedy for complex applications but fine for applications like the rotary dumper.

The positioner is controlled by a small, geared stepper motor with a limit switch at one end for calibration purposes and "dead reckoning". I purchased the stepper, together with toothed pulley and belt from Makerstore in Melbourne, Australia. The mechanical rail and slider are 3D printed, inspired by extruded aluminium V-rails used for robotics, but of more compact design.

The arm of the positioner has a small servo motor. I have since redesigned the pusher arm to push on the end sill of the wagon rather then the bodywork. The Picaxe has inbuilt commands to generate the required pulse width modulation signal for servo motors.

Likewise, the gripper arms are controlled by a servo motor located under the rails. I have yet to work out a better way of handing the cables connecting to the moving parts. Ideally, I would like to power the rails through the dumper too so a loco can drive through if required.

The dumper rotation is powered by a Switchmaster slow motion point motor from the US. This is a just a geared motor which does 60 rpm. I found it had way too much torque for operating points, so I use Tortoises for points. However, it works well for the dumper application. The gear on the motor output shaft is part of a set bought many years ago at an exhibition, and I was able to print matching teeth (2 mm pitch) on the end frame of the dumper. Ideally, the teeth should extend around a greater arc so the dumper can tip a full 180 degrees (because I changed the position of the motor from beside the dumper to underneath). This motor only draws 9 mA from 3-4 volts, so I am driving it directly from 2 Picaxe outputs (rated at 20 mA) via a dropping resistor. There is a limit switch in the home position and the amount of rotation is done by timing, before the direction is reversed.

I have a small OLED display (16 x 2 characters - AXE133) connected to display a simple menu-based user interface, and a 4-way keypad for menu selections. The software allows manual operation of various elements for test purposes or automatic dumping of a selectable number of wagons.

 

There is currently no sensing of the initial train position, so it relies on the loco to position the train fairly precisely, then the loco is detached prior to commencement of dumping. In the era I am modeling, trains had guards vans so the process starts with the guards van inside the dumper and the first ore wagon next to the dumper.

Over the last few days, I have converted the wagons to Sergent rotary couplers which work better than my homemade ones. I 3D printed extended coupler boxes for the matching dummy couplers to provide additional spacing between wagons to give clearance for the vacuum hoses and steps while being dumped.

[lyneux]

Thanks Richard, a comprehensive response.

 

More detail photos please!