doug72

Update:- Now tested using a Z28 Turntable and a shock absober and not good news. Although the dumper was rotated by the train unit OK, the train axle with 8T gear that engages with the 24T gear starts to skip as the tension builds up in the shock absorber spring before it is released to reverse the train unit. Also found it is also harder to set timing correctly. I have reverted to using the Z56 turntable and shock absorber set up as I know it works well. As @dunes said before there is more torque using the Z56 turntable and less strain on the gears in the trip system. I would recommed using a Z 56 turntable with either a shock absorber or rubber bands.

It might be the same part as used on other PF motors.

You also need to reverse the two, LEGO Technic Beam 3 x 0.5 Beam with Boss and Pin (33299) which move the PF switch. It was only a problem in the rotary dumper where it snagged on the part of the framing. As the trip hits the beam midway don,t know the reason why iit was 15L. An 11L beam would Work OK & reduce weight.

It would make agreat GBC module especially if coupled to the train system !

Thanks for your comments and queries. That’s how I started, simple modules to begin with, then progress to the more complex modules, and then set about improving them to be reliable. re bsx files, I couldn’t figure how to access these, so I used the parts list that can be found at the end of the each pdf instructions. Printed a copy and then checked what I had and what I needed to order. re train unit yes just I changed the 15L beams to 13L. Arms which “fixed the problem. @dunes is working on the LDD files for the rotary dumper modification, and reversers using rubber bands. see his post to access these. Good luck with your builds,

Found this on YouTube: an animation of the Hunlet bucket operation, which uses roller chains.

I have seen several models of this machine built using Meccano, try searching on YouTube. There are also HO scale models on US model train layouts. Its a very complex machine.

16 x 8 tiles might be more economic for the track outside of the yellow line on the straight sections.

@dunes Wonder if the train motor problem you had is the reason why the your first attempt using a Z28 T/T & Shock absorber did not work. Will try a Z28 with shock absorber with the improved drive gearing, on my build before I use the rubber band version.

Thanks. Underside view:- A 12T tan single bevel gear is missing from the LEGO Beam 3m Ø4.85 with fork (87408) that the train drives the rotation and trip system.

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Good progress. Is it possible to do a render from the other end, should then be able to check the whole build. Doug.

Many thanks, I won,t be able to fully check until I,m back home. Can,t download LDD onto iPad. From what I can see on the image looks correct. Where do the two black pins you mention go. Only thing I can see is missing is the #2 connector for attaching the elevator module. IMG_5868 by Doug Ridgway, on Flickr

Lego 25mm rubber bands, Red v Blue. Do they have the same tension force ? It seems there are two sizes of blue bands, 25mm & 26mm. So a 26mm will have less tension then a 25mm Red band.

Does Train un it work when you manually push the trip bars ? If so there might be not enough force from the rubber bands to rmove them fully. Try increasing the rubber band tension. Also check PF cables are not impeding thie trip bar travel. Check the PF connectors for poor contacts. LXF looks good. Doug

One final fix, the vee reverser using rubber bands has enough force to knock the front wheels of the train off the track as it exits. Easy fix, 15L side beam added to prevent this. All problems now resolved.

Checked the LXF file and all OK except the trip arm where I made a small change as the 3L thin beam could sometimes catch as arm fully retracted. 2L thin beams (blue) used instead, with 3L axle kept - which helps guide the arm as it fully retracts. Photos show this

Thanks for your excellent work. Can you also do the other variations i.e Z56 with shock absorber and Z56 with rubber bands. I will be away from my main computer and Lego work station all next week (dog sitting !) but will have access to an iPad so I can review the LXF files when they are ready.

Many thanks, I think all the problems have now been resolved. I run it every day and it has proven to be very reliable, with consistent discharging of the empty train unit. This is the version using Z56 turntable and a shock absorber. The trip unit with Z28 turntable version using rubber bands also is reliable and I intend to install it in the dumper to test its reliability. Both T/Ts give the rquired 21:1 gear ratio to rotate dumper and syncronise the train trip unit. Only thing that needs changing is the position of one 12T single bevel gear to get correct rotation of the trip rotor arm and the gear train that drives the Z28 T / T. Discharge chutes as required to suit your needs for GBC connection. Only train module that occasionly gives bother is the elevator dropping before the latch holds the lift platform, working on improving that. I hope you can build this in time and look forward to seeing a video of it in action at Utrecht.

Rotary Dumper Reversing unit:- Finally got a Z28 turntable to work using rubber bands. The problem with skipping gears has been overcome as shown in the photo. Two 12T double bevel gears in series mesh with the Z28 gear ring by using thin 3L beams with axle holes (green) as spacers to get the two 12T bevel gears to mesh together. Tested using two rubber bands and train reverses OK. Also tested using a single rubber band and enough power to hit trip bar and still reverse the train OK. I found the solution in Machines & Mechanisms Book by Isogawa

That’s the only reason I would buy it, maybe if it drops any further.

42070 £119.99 today.

Camera battery recharged:- Video of rubber band reverser unit for the Rotary Dumper. Temporary track set up to demonstrate. Reverser at other end has 4 lobes hence the quick reversing. Now will rebuild using a Z28 turntable to see if will function OK. Now tested with Z28 T/T & it does not work. Managed to eliminate the extra right angle drive but the 16T idler gear keeps skipping as too much torque required to rotate the Z28 gear when the red arm starts to push the trip system against the force of the rubber bands. So a Z56 turntable is only option for the Dumper mod. See next post

Rotary Dumper - reversing unit using rubber bands & Z56 Turntable gear. I have now developed a reverser unit using Lego red silicon bands. Trip arm travel is 2L. More compact and the overhang is reduced by 2L to give more clearance for ball chutes. The two LEGO Minfigure Neck Brackets (42446) are no longer required. See photos, video tomorrow once camera battery recharged.