Leif

That is a really big crane! Most impressive! I will look into the details of your build. Any LDD or similar?

This is an old topic and I apologize for bringing it up again if bumping old topics is frowned upon. However, the question is the same and the best answers, so far, seem to be in this thread. Parallell with the mobile crane project that we got going in the forum right now, the Grove GMK 6400, and the Efferman actuator for this as the current setup so to speak, I have started looking into building a mechanic actuator for a crane. I have built the more or less classic rack and worm gear actuator, but it can actually not stand more lifting than approx 1.5 kg before worm gear slips! See pic for principal setup. naturally gearing down at the other end of the actuator as well as a perpendicular setup or similar.. Any ideas for building a stronger actuator? As I understand there are some actuators being built that we still have not seen the details of, how they were made. Their strengt I do not know of though. I think that an 8 tooth gear towards the rack is more stable but we will add height to the actuator for sure, and it will be quite clumsy!

Thanks, neat idea! I will certainly look into this, space consuming though..

If it feels pretty tough to turn the gears manually, that is probably the issue. you tested the motion not through the supersection? the remaining gearing adds even more friction. Look through the drivetrain to the the outriggers, all the way from the motor. probably too much friction. this drivetrain is really long and complex!

Same topic but new angle.. I recently destroyed my first (yeay.. ) gear.. Bewel gear in center diff when I had center diff locked so rear and front axle both had to work. Have you thought about it? when you build a center diff, lockable, you actually only lock one of the axles strongly with the diff. the other axle has to be driven through the three tiny little weak bewel gears inside the diff.. The solution should be something like pic below. naturally diff suffers from bracing and however you brace it, it will not be near the gear. Driven from both sides is a recommendation. Thoughts? experiences?

Stealing with Pride is already Mark III Bracing in a whole new way. elevated drivetrain with interim solution for center diff lock. Diffs on axles are also double secured with bewel gears in both ends, thanks to all who helped with those ideas The elevated drivetrain also gives an option to add a third axle, driven directly from drivetrain and not via bewel gear on second axle. Drivetrain is now so braced and diffs are so secured that I actually wrecked a gear in center diff. This is a build that I first entirely created in LDD, and I have learned a lot. I am now pretty fast in LDD and know the shortcuts. It takes time to build in real life. try, build, tear apart,sort parts. LDD can often be quicker but it is still only theory! Build as well! Some impossible pin mountings can be done in LDD but not in real life. look for them, and replace them with 2L fric with snap hole for easier/doable mounting I saved some time, only one side is done in LDD. other side is repetitive and easier to build when the view is not obstructed. LXF here: https://www.dropbox....ummer2.lxf?dl=0 And some pics!

Yeah, well you got me there but I would prefer to see this as a part of a solution for, say, a 4WD or such where motor goes through center diff, sturdy gearboxes and all that you know

If you have the space, this construction is almost foolproof. Apply sturdiness and bracing at your own convenience Only concept. But I have build it and engine stalled rather than gear grind What I actually solved was how to not change gear direction and keep it in three studs length. 16T with 20T did the trick, legal it is! I dare you to grind this

Rebuilt and improved. More or less the whole thing, at least I had to tear it apart to get all those beams and pins in place.. Improvement mostly using "Double Angular Beam" in order to reinfoce between layers. The weakest link right now is actually sideways since it is built more in "line" than crossover, so far. I might add third axle, and/or centre differential lock. time will tell. Thanks to Crowkiller and other guys for gear grind in diff. Now I actually managed to stall the engines (or the batteries) a few times rather than gear grinding! and some pics, no more "kissing the table"

Ah, I thought the gear could slightly wander off the axle so the stop was preferred at that end. But maybe that's just a theoritical issue..

Nice idea Doc, I will look into it! Seems to cause some friction? Yes you're right. Stop at gear end or other end?

Thank's a lot for good replies all of you. Yes Paul, I have been toying with that kind of solution and noticed some improvement. Would you recommend something like this (diff excluded..) or ever more solidly based? The tan pin without friction is a bit wobbly itself, maybe but a 3L axle on that side as well.

Gents, I have build some strong machines, powerful, geared down, lots of motors coupled together. But the weakest link, and it is pretty weak, is always the perpendicular gear at the diff. Even though it is most of the time a 1:3 gear down in a portal hub after the diff, you will get gear grind.. "Funny" thing is I have noticed several times that the gear grind will appear even on only 1 XL PF motor, so the second motor really cannot do any good. Before we can use its power, perpendicular gear have given up... Any advices? Not happening to you...? revert to old style Diff? More complex gearing but sometimes that may be the best solution. see pic, Bracing is what it is so to speak..

I take that as a blessing Sariel, although I wouldn't hold my breath waiting for me finishing... I am really bad at body work, chassis - that's my deal! Funny thing, current length is 63 studs, same as orig Hummer, and that is a coincidence. I am right now enforcing and actually shortening a bit but also making rear axle more modular and I will then add a third axle, just for fun! This beast can really pull anything after that..

Yes you are correct. I first thought you meant different spacing top and bottom of shock, which was a misunderstanding. Anyway, The Hummer I have borrowed the solution from has the same solution and I can promise you, it is just a matter of miniscule touching spring-beam, nothing more I can say about it. 100% legal? Not for me to decide. Build and test and you will see that it is not an issue, I can promise!

Yes probably a bit too long. Right now it's just a matter of several 15L beams together more or less. Tuning and cramping of gears and such is next step. I discussed with Sariel on his website about the springs "jammed" into steering arms and other parts and he reassured me it was not an issue. check out his pics and you will see the same there. "stolen with pride" has to include some solutions from the original to qualify! Can you elaborate? this is the setup at front axle, no half stud bending: Yes, I have doublechecked, all axles and gears are in place

Well at least it's not "kissing the table", that I have proved, right Probably I will shorten the frame a few studs as well. There are some areas that can be improved and there is right now very little reinforcement between upper and lower layer. To get sturdy, for real, I have to add some studded beams, which is not a bad way to go. those two BB and those 4 XL, darn that is some serious weight!

Optical illusion it's not that bad! this is pic from better angle. Yes that is correct, Sariel's Hummer, latest edition. No intention from me to build a Hummer altogether. More of step forward in good chassi, portals, individual suspension, strong and all those key components. The beast is really strong. Climbing is really good! I don't think so. they are quite comfortable where they are now. almost too little compressed so steering and such is a bit raised right now rather than straight. Well a body will most certainly fix that!

Anyone see who and what I am copying? Entirely built in LDD and tonight in real . Built with respect and admiration, for my own amusement and learning curve.

Oh yes, but PP tires and current Lego motors (and gears..), that will never happen..maybe some RC motors but those tires really are like a giant flywheel - and with friction as well... I have now decommissioned this build, having finished all my POC, Proof of Concepts I was aiming for. For example, the "Technic, Steering Arm 5.5 x 2 with Towball Socket Rounded, Chamfered" (why 5.5, it really is 6 in length?!) works really good with the regular 6 length technic steering links for independent suspension and no bump steer, but really cannot hold everything in place when you start to climb rocks! Live axle is the only solution for climbers, I now have concluded..if you want true strength..

Yes you are probably right but so far I have only focused on proof of concept of drivetrain and steering. Extending the chassi is just a matter of longer beams and will be done!

Some progress and actually a chassi built. This is a crawler with the PP tyres and it is really a challenge to build something that can keep them in order! Features independent suspension on all 4 tyres and finally I think I have everything stable enough! Testdrive showed that the steering links could pop out so I made "reinforcments with a vengeance " see LDD pics below which are now in place as well, the images below are before it got mounted though. Anyone else experienced steerings links popping out int this kind of build? And with "this kind of build" I mean crawler with PP tyres and similar! For me I think it's as much as I can do with 4x4 and independent suspension. This really shows that you got to have live axles and nothing else when it comes to deliver real power...!? https://www.dropbox....ering4.lxf?dl=0

Today I caved in and choosed the portal hubs.... At least I know the reason why I have to do this. Making the steering and the hub powerful enough, I could at the most save ½ stud compared to just mount it all on a portal hub....too much bracing and brick next to brick to get the results (ackermann, no bump, sturdy!) Yeah, pivots for steering are not optimal but I have to avoid those dreaded CV joints...at least for this crawler/monster! So now I got strong setup, good gear down after differential which should mean no/less grinding. But first, London and Bricks 2014 for some days now

thanks, I got the 42000 hubs, 8466 hubs and some more, but CV = breakage! there is no way you could build a strong crawler with huge tyres and CV joints... My build has to be with UV joints and centre point steering must be "as good as possible" due to the build around thoise joints. The race hubs with CV are always the best solution for steering geometry but they wont last when it comes to forces being applied...

of course but that would mean wider chassi and/or the dreaded portal hubs...