doug72

Could you put a link so we view it, I would interested in understanding how it works. Doug

Thanks for your comments. There is still room for improvements for the rotating dumper / reverser unit. The two 140T gear rings were "racking" as hopper wagon entered & exited the dumper. Two additional stiffening axles added at 90 degs to track and hopper guide rails and extra 2L pins added to gear segments to stop any spreading, Rotary Coupling: At the moment only straight tack can be used as only rotates in a horizontal direction, for curved tracks a flexible coulping has to be able to move in both vertically and horizontally. Still looking for a solution. Re Baseplate - 56L X 28L: Have shifted the / reverser dumper unit so that the end of first section of track rail is in line with the edge of the baseplate. The other baseplate will have the loader station and reverser with its track rail end lining up with edge of baseplate. The two units can then be worked on individually and linked togeteher once all OK. Overall length will be 112 L or 89 Cm. I have had the train and hopper wagon running back and forth repeatedly (reversed by hand at loader end) to sort out some issues and extra guide beams added to ensure wheels roll over the joint between static & rotating track rails.. There is a 0.5 mm difference in rail height between track in the dumper & the elevated track section. Can't find a way to eliminate this but train wheels cross this OK with just a small bump. Next step is build the reverser for the loading end. Train car has to be slightly adapted so it hits the stop but at same time allow the hopper wagon to preceed it. Extentions added to one end of train unit to align axle 8T gear with the reverser 24T gear. Re Gear reduction calculations: When designing I often while watching TV have a note pad, pen & a calculator to sketch out ideas etc. @Sariel Lego technic Builders guide 2nd edition has a gear reduction chart on page 59. - very usefull Yoshihito Isogawa "Machines & Mechniams" book has a good section of meshing gears to obtain different ratios by using unusual gear combinations & parts etc..

Video of dumper rotating with the hopper wagon in dumper and the train unit driving the dumper and the reverser. Note:- trip arm removed from the reverser for video purpose only to demonstrate the rotary coupling between hopper wagon and train unit. General view: General view: Reduction gearing to drive dumper at 21:1 reduction There was insufficient room to install a drive to the 140T gear ring for dumper at the reverser end. So had to devise away the drive the other 140T gear ring It took quite a while to sort this out as could not use a 20T double bevel gear meshing with the 140T ring to get the required 21:1 reduction as it would foul the underside of the train as it passed over. Tried an offset drive axle but run into problems with the dreaded 1/2 stud offset, due the need to use studded technic beams etc. Eventually came up with a drive on the centre line. 2 x 12 gears on same axle act as idler gears, the top 20T gear drives the outer 12T gear. A second axle has a 20T engaging the other 20 T gear & on same axle there is a 24T spur gear, driven by a 8T gear from the reverser via a drive axle 44L long. This setup gives the required 21:1 reduction in a compact unit. Drive from reverser to long axle that drives the gearing to rotate dumper. This required two LEGO Beam 3m Ø4.85 with fork (87408) at 90 degs to each other and 1L apart. Connection seen in video a bit weak so have devised a stronger connection. Reverser unit: A more compact version devised with Z56 turntable & rubber band. Overall trip rotation is 21:1 via 24:8 & 56:8 = 3 x 7 = 21;1 to be in sync with dumper drive. Timing: This is easy to adjust in 140 steps by removing the outer 12 double bevel gear- adjust 140T ring gear and slide the gear back into place. Tested hopper & train enter and exit dumper OK. Next step is to build the loading station and reverser plus a elevated track section or possible a different type of elevator. Studded base plate This is non Lego but I find it very usefull when building as you can re-aranage parts quickly instead of having to build new frame supports. Once build is finished - base plate removed and proper framing added between the various sections.

Doug's :- Rotary Dumper - Through type with sepearate hopper wagon. Success it works After an epic struggle to get the drive from reverser to turn the rotating dumper finally achieved it, First test failed & tracks would not align properly, found I had forgotten a 24/8 reduction in the reverser but easily fixed. Tested again and tracks line up and train enters & leaves OK. Dumper rotation very smooth and timing very easy to set. I have opted for full rotation. Reversers uses rubber band & the Z56 turntable as a gear to achieve the 21:1 reduction required to rotate the dumper 360 degrees. Tested with hopper wagon attached and entered and rotated in the dumper while still connected to the train as it drove everthing in sync. The rotating coupling works smoothly. Some images below - I will describe more fully tomorrow. Devising gear trains for rotation was the biggest problem, the dreaded1/2 stud offset at work again !!! Video later. Track to be extended and the loading station built. Once all built I will make a proper frame structure to support everything. Next task is clean up my work station - its a mess with unused parts all over the place. See next post for more images, video and a more detailed discription.

I thought that was the reason. Work on new through dumper going well, thought there would be a problem getting the gear ratios correct as can only get a 12T gear to drive the large 140T gear ring, A 20T gear would foul the underside of the train, but now figured how to get same gear ration of 21:1 so train release will be in sync with full rotation, using a 56T turntable for the reverser. Now tested and works fine with train stationary in the reverser and dumper rotated by hand with hopper wagon inside. The rotary connection between train & hopper wagon works well. Drive to dumper still to install. It will be a lot shorter overall than the Yattaran module.

Great to see it running well at a public event.

Yattaran Rotary Dumper ( Reverse engineered ) So far have built the longer rotary frame, hopper wagon, track and the reverser track on the test rig. Progress has been slow and very frustrating with all sorts of problems. Mainly due to obtaining an effective way to un-couple the train from the hopper wagon. The video shows a big jolt when this takes place. I found it takes a lot of force to pull apart the Lego train magnetic couplings which causing the dumper frame to distort in direction of travel. On the rare occasion the coupling parted the hopper wagon was catapulted backwards out of the dumper as frame return to original position. So a radical rethink required. Concluded that the Yattaran dumper is over engineered and very complex and have therefore abandoned in further attempt to replicate it. Instead I will design my own version (D’sRD) of a rotary dumper that will allow the train to run through & stop in the reverser but at same time allow the dumper to rotate to empty the hopper wagon. Wether this will be partial or full rotation, have yet to decide. This is how some rotary dumpers work which requires rotary couplings. My D’sRD version will use a Z28 turntable to achieve this and will use the short dumper at in order to use 1 x 16L track beams Side view showing train coupled to hopper wagon. End view showing train alignment as it as it would pass through the dumper before engaging with the train reverser. Horizontal grey beam with green pin is only to show that the Z28 turntable rotates around the dumper horizontal & vertical centre line and allows the hopper wagon to rotate & empty while still connected to the train. Synchronisation should also be easier.

@Berthil Thanks for that information, perhaps if we don't run our train systems for long time, it would be best to release the tension of all rubber bands used including the reversers. As they are relatively cheap compared to shock absorbers I shall keep a few spares.

Elevator Trouble: Further investgation has found a weak rubber band - see image. Left: blue band in use on elevator trip for lowering had streched ! Not sure if was a 25 or 26 band or if brand new when received. Right: new blue 25mm blue band Now tested elevator with a red 25 mm band without the double wrap on one ball pin and working OK. Something to watch over time & check if any issues as there is tension on this band even when not in use. Wonder if high ambient temperature could be the cause. PS the band seems to be slowly returning to normal size now there is no tension - odd.

Based on your cycle times and balls per trip estimate you moved over 19636 balls yesterday - thats a lot of balls !!!

@Berthil elevator dropping problem Tested my set up this morning and the elevator when lowering sometimes OK but then started dropping many times without apparent reason. Removed elevator from layout to my work station for trouble shooting. Found it is due to incorrect tension on two blue rubber bands, for the trip latch that keeps elevator at the top position and the other for the trip that lowers the elevator. Also found that the exit chock does not hold the train in position and is only there to stop a train running over the edge when at upper level or during lowering. The yellow trip arm has to have enough tension to push the train back against the vertical bar so that the 8T gears stay in correct mesh with the 24T gear so that the 8T gear engages to control lowering down the four racks. Both blue bands control provide this tension. The blue bands have to be wrapped around one pin / ball twice to have enough tension to hold train in correct position but at same time allow the train to release the latch to lower the elevator. Now lowering OK. See images. Rubber band for latch to hold elevator at upper position Rubber band for trip to lower elevator Train hold back lever (yellow) to keep gears engaged and chock (red) to prevent train runaway. Note the gap at the chock that does not hold the train in position.

Many thanks for your feedback observations, glad it worked well and that you had a good day. Did you get a video and how many cycles do you reckon the dumper made ? Timing sync reliability has now been well proven with your test run. Trip bar swinging 3 x 3 thin lift arms: Try putting the pin it swings on in the other hole, it lets it ride up on the trip bar better, can also depend on which way train is on the track, the side with the PF plug can get in the way. Shorter trip bars also help so that don't catch on the train locating lugs that ensure the 8t gear stay in mesh with the 24T gear. I cahnge them to 13L. On one of my reversers I used a 1/2 bush to adjust to shorten the push rod to allow swing arm more rooom to drop down tothe trip position. The trip arm on the Yatteran dumper is different and doesn't use a 3 x 3 lift arm, need to try this on the next project. Elevator: Can be sensitive, works OK one day , try the next and it crashes down on first cycle and then seems to settle down and run OK. I found that playing around with the diameter of the stop pin allows for finer adjustments, i.e, use a 1L beam over the pin. Might be temperture affecting it - my conservatory has ranged from 35 C+ to less than 20 C over past few days so parts can expand & contract. Batteries: I am using rechargeable AA batteries, that seem to last quite a while but its a bind having to remove them to recharge, but when they run down I get the same problem that not enough power to lower the chocks to enter dumper or to hit the trip to lower of the elevator. I must try and see if come up with an adjustable stop for the elevator raising. Next project Now under way with rotating dumper, track system & hopper car completed. Doug.

GBC Rotary Dumper (Through Type) (WIP) Re Dumper length: At the moment it is 16L same as the track length, but now found a way to make 20L by using 5 pce. flexible track mounted on an under frame. Hopper wagon retaining rails may need modifying. ======================================================== The original design of this dumper (by Yatteran) uses a lot off flat 8 x 1 tiles and 1 x 2 blocks with 2 holes to form the track for the train & hopper car to run along. Designing with LDD means you have unlimited parts, unlike the limited range of parts I have available. Therefore I have devised an alternative track system using 1 x 16 straight rails, these have a serrated edge to give good traction - needed at the point where train detaches from the hopper wagon. There is a slight gap between the tracks on the dumper and the linking track but the train wheels pass over the gap OK. The transition from 1 x 16 rails onto the reverser section is also smooth. Unlike the Akiyuki system the the trip mechanism is on the other side of the track. Undecided if use this configuration or not. I have now built a test rig (on a studded base plate) with rotating dumper section, linking tracks and supports for train reverser track section. ( trip parts to be added later ) A compact auto change drive unit built and the next step is to work out positioning of this and the gearing required to cycle the dumper, lock rotation to line up the tracks and the train release timing. The original design rotates through 180 degs, but I think this can be reduced as long balls fall out OK and might make gearing easier. Final frame supports to be determined once gearing sorted. This is going to be a lengthy process ! Image shows the short dumper Mind the gap ! Reverser track section.

To enjoy building what you like to the best of your ability and learn from others.

I,ll keep the length for now, easy to increase later if required. Figured out the spacing for the support rollers, with tires & the 12T gear so that it meshes correctly for rotating the dumper. Have to work out the gear reduction required to cycle the rotation I think it all can be driven by the train motor to cycle the dumper & run the train reverser. The horizontal discharge conveyor in the video seems to be powered from the loader. I will be using 1 x 16L track beams with tiles to fill the gap each side of the dumper.

Thanks the video is very usefull especially when run a 1/4 speed. GBC Rotary Dumper (Through Type) (WIP) I have made a start of building this version which will be used as a shuttle system and not directly linked to the Akiyuki system (except by a loader & unloader conveyors). It uses a separate wagon with non detachable ball hopper shunted by the train unit instead of carrying it piggy back style. I have made the rotating dumper frame shorter than that seen in the video as provided by @dunes to make for a more compact system. GBC ball transfer wagon built and as I have run out of LEGO Panel 1 x 4 x 3 with Side Supports, I used LEGO Train Window 1 x 4 x 3 instead. This is OK as the ball hopper uses rollers & guide rails to locate and retain the hopper wagon as the dumper rotates 180 degs. & back again. Now the hard part, determining the gear ratio to rotate dumper through 180 degs. & back again before the train car is released. I will be using an auto reverse gearbox to achieve the required dumper rotation cycle.

The BMW Mini is a tank compared to the original Mini !

Many thanks for your comments. I like problem solving, it was a big part of my job as a C/Eng at sea ( now retired ). Re Through Rotary Dumper; I will be using 1 x 16 Track rails that have a serrated top edge for better wheel grip which will help the train seperate from the hopper car. Looking at the video @dunes found there is quite a jerk as the train pulls away from the hopper car due to the magnetic couplings., fixable ? Potential problems:- How to line up tracks for each cycle and obtain partial rotation & return or go for full rotation. @Berthil Re the event you are going to this weekend and displaying your rotary dumper, good luck and I hope it performs all day trouble free, wonder how many rotations it will do ? It will be a really good test of all the modifications. I read somewhere that Akiyuki was moving away from the the GBC Train system and only devising GBC modules now. Doug

Many thanks, a much better video than the one I found. Video already usefull as i was going to use the guides for the hopper car as per Akiyuki dumper which trains sometimes stick if parts have come loose. The top rollers should be more better for locating the ball hopper car. Have made a start on a shorter rotating frame and a hopper car for the balls. Will be quite a challange taking some time to work out how it functions.

Main additional parts required are:- 8 pce curved gear racks for the static gear ring. 1 pce Z56 turntable for correct timing. 2 pce Red rubber bands for the train release trip Other parts can be found using the LDD file.. The three steel ballast balls are not required.

Double Reverser & Double Crossover track. If using the LEGO Double crossover track then two switches have to be modified with rubber bands as per Akiyuki instructions. If using the 3D printed double crossover track then NO modifications are required as each switch blade can be set independently.

The rotary dumper is working fine and no more fine tuning is required, three have now built by myself, @dunes & @Berthil all test run without issues. Rubber band version works well and dumper rotation cannot get out of syncronisation unlike the cam lock system of the original Akiyuki design. Ball collection chute is built to suit individual requirements, Full height required to meet GBC standards or lower height if only for a train layout system. The @dunes LDD files are done - if you hit any snags building it please get in touch. I hope to later devise a "through" rotary dumper. The elevator part is the hardest to get working correctly to release the train into the dumper.

The elevator can be very difficult to get the setting correct - its takes a lot of trial & error. Mine tended to get stuck on the chock which hadn't lowered enough or train stuck on them until it rode up over it and moved off with a big jolt. Finally got it set. Had thought of using an adjustable stop to release the chocks - I'll see what i can devise. As I needed some more balls so I thought of using some glass marbles, big mistake, elevator didn't like the extra weight and elevator kept crashed down as train left the dumper. Marbles now now discarded & extra balls place on my Xmas gift list. I to have had bother with the double passing module so not used for current layout but needed once move to the loft. There is an issue about a 1/2 stud offset on one of the racks which is mentioned in earlier post by @Jonas, mine was incorrect and once corrected works a lot better. Once the final LDD file is made wonder if PDF instructions can be made by someone.

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