Splat

With my current project, I'm treating it as a series of multiple sub-systems (drive-train, gearbox, suspension, etc), so I have different versions of those sub-systems all still assembled. After the current project is finished, I will most likely disassemble all of those sub-systems though. I tend to keep pre-built sub-systems together, until I need the parts again, or I need to make more room. In that case, I will usually take some photos and/or recreate the sub-system in LDraw for future reference.

If you increase the size of the wheels, but keep them rotating at the same rotation speed as the smaller wheels, then you are increasing the overall speed of the unit, and it is more likely to go too fast and turn too fast. If you want to keep it following the line nicely, then you may have to slow down the rotation speed of the drive motors a bit. Or perhaps reprogram it so that it doesn't turn so much, so that it continues to go fast in a straight line, but turns slower in the corners.

@DrJB - I do not have any means of viewing an LXF file at the moment, so I purely used the image in the first post as my reference. When I built this myself, it didn't work too well for me, and I just wanted to share my experience in the hopes that you might be able to make some suggestions on how to make it work better. If there are other pieces required that aren't shown in the image above that make this design run better, that is great, and I'd love to see a video of it in action. I do understand that your design and piterx's design are similar, yet different. I didn't compare this to pitrex's design, I was merely trying to point out that piterx's solution solved a small issue that I think your design still suffers from by putting modified 1L axles into rubber connectors.

@DrJB - have you tried making your free wheel design using real pieces? I built this free wheel on the weekend (based on the pic in the first post), and while it 'sort of' works, there are a few problems that still need working out: First, the section in the middle is just 'floating' there. In real life it isn't being supported by much, and tends to wobble and twist a little bit when everything is spinning. Secondly, the Axle Connector Double Flexible (Rubber) pieces tend to flip the wrong way when too much resistance is applied to the output, basically reversing the direction of the free wheel. I think this is why piterx inserted those modified 1L axles - to prevent the rubber parts from flipping the wrong way. In your design, it doesn't help that the 8T gears are 'trying' to make them flip too. If you have built this and it it working better for you, I'd love to see a video of it in action.

For Lego purposes, I don't think that it really matters which part of the differential the axles are connected to. As long as you have one input and two outputs, or two inputs and one output, the differential and spider gears will rotate as needed. In real life applications it does make more of a difference because you don't want the smaller spider gears rotating as much, causing unwanted friction and heat within the differential.

Great creation you have there I'm always impressed by these types of mechanisms.

Nice work on the steering I've seen bushings used with worm gears before, but not with standard gears. Do you have any video so we can see how fast this model moves?

I agree! It may not be 'on-demand', but it doesn't need to be. As soon as one wheel loses traction, the diff locks up, effectively transferring all torque to the wheel that still has traction. The other benefit is that it doesn't have bands or clutches that reduce the efficiency of the system, and it can also allow the vehicle to go around in circles without locking up (which some of the ones in this thread will do). There are a few different designs, but this is my favourite one: If you replace the large turntable with the new smaller turntable (99009 and 99010), you can get this even smaller.

Nice work on the new cement truck I like the steering on the new model.

Nice work Doc_Brown I can't wait to see what you come up with next...

Hi KiwiFalcon, it's not a problem - we are all here to help each other out. I'm glad that you got it working. Welcome to the forum.

In Hrafn's redesign this piece doesn't work, however in my original design it does as it doesn't interfere with anything above/below the central axle, and therefore the axle goes through the holes of the steering wishbone, and it allows the gearbox to be one stud shorter. The changing of gears can then be controlled via a steering link (http://www.bricklink...tem.asp?P=2739a) which can be controlled via some sort of rotating mechanism, which can be controlled by a servo motor. I'm still trying to work all of this out at the moment to get it nice and compact.

Check page 3 of the 'Track3r' instructions : http://cache.lego.com/bigdownloads/buildinginstructions/6052132.pdf With remotes, typically the battery compartments are screwed closed. I think this is so that little children don't open them up and eat the batteries, or something like that. So yes, you have to unscrew this compartment, and put in 2 x AAA batteries.

Great work Nico. I'm a big fan of your Lego machines.

I like your design - it is nice and compact. I have one question though - it looks like your input from the motor is the black 10L axle in the middle, and this has a 16T gear on it which should fit tightly on on the axle, so how does it slide back and forward to change gears? Thanks for the credit It's always good to see someone take one of my ideas and continue to develop it further. Another part that can be used for the shifting mechanism is Technic, Steering Knuckle Arm with Ball Joint

It is probably a good idea to replace the universal joints - they were only added afterwards to attach the motors. Yeah, these aren't the best 'instructions' that I have made - they are more like 'plans' rather than 'instructions'. They were mainly created so that I can recreate this gearbox at a later time, and can reuse the parts for other things until then. I'm glad you got it working. Let us know how it turns out once you incorporate it into your 4x4. There are many, many ways to create the shifter. I have tried to make a lot of different types of shifters, but most of them suffer from the same problem - they take up a lot of space, including the linear actuator method. If a rack and pinion is used in this design, then space has to be provided to allow it to slide back and forward, and a supporting structure also has to be created to make sure that it slides smoothly. It is definitely an option though. I do have another method for the shifter that will be a bit more compact, but I need to perfect it before making it public.

I haven't used mine too much, but they all seem to work the same as when I bought them. Perhaps you can contact Lego for a replacement (https://service.lego.com/replacementparts#WhatBrick/42010).

It's a pity that I couldn't be part of the competition to defend my title from last year (I don't have access to my Lego pieces at the moment), but congratulations to all the entrants, and to the winners. Thanks also to Jim and Eurobricks for putting together the competition.

I created a strong gearbox which you can see here: http://www.eurobrick...4 I still haven't incorporated it into a completed MOC yet, but someone may be able to use it as inspiration.

This is what I normally try to do when I am trying to model an existing object in Lego: Find a 3D file of the object original object/vehicle somewhere on the Internet Use MeshLab (http://meshlab.sourceforge.net/) to open the file Export the mesh as an STL File (turn off binary encoding during the export) Open the file in a text editor Notepad will work, but I recommend something with a bit more power. I actually use Excel (import the file as a Space Delimited Text File) as it allows me to delete whole columns, and perform calculations on the values to get the scale right. Manipulate the data as needed to get it into the LDraw format (http://www.ldraw.org/article/218.html) If you are familiar with regular expressions, this can speed up the process, as can functions in Excel. You can either just use the edges of the surfaces to create lines in MLCAD, or use the points to create triangles/quadrilaterals in MLCAD. Save the file as a TXT file Rename the file to an LDR or MPD file Open the file in MLCAD You may need to modify the file to scale the points/lines/surfaces as required (Excel works well here). Pick something that you can use to base the scale on, such as a wheel. Depending on your computer, MLCAD and LDView will have a bit of trouble if there are too many surfaces present. A tip is to use MeshLab to reduce the number of surfaces (Filters > Remesh, Simplification and reconstruction > Quadratic Edge Collapse Decimation). It takes a bit of work, especially when having to manipulate the data, but this gives you the object in 3D inside MLCAD, and you can then start adding standard Lego pieces in MLCAD that conform to the shape of your 3D object. I first start to build up some of the shell/body work, and then build the chassis inside it (using MLCAD sub-models). Also, don't forget about Sariel's Model Scaler tool (http://scaler.sariel.pl/), and Scaling Tutorial for Vehicles (http://sariel.pl/2009/12/scaling-tutorial-for-vehicles/).

14 : 4 23 : 3 22 : 2 11 : 1

The easiest way to make the monster truck lean to the other side while it steers would require that the ball joint on the front axle would be at the front, and the ball joint on the back axle would be at the back, similar to how a skateboard works. I'm not sure that this could be done easily without totally redesigning the chassis of the monster truck. At this size I only just managed to get the drive and steering in place.

Hehe, yeah, it's taken a while for me to post this on Eurobricks. I put this together at the beginning of September, and posted a 'teaser' pic on Flickr and more pics on Brickshelf. Then life got really busy (major projects at work, family visiting from overseas, etc). I've finally found a little bit of time to post it here and take a quick video.

I have created a short video of my motorized and remote controlled (IR) version of this year's Monster Truck set (42005). Sorry about the audio quality - it was a very windy day! As you can see, it can handle small-medium sized rocks and bumps, but it is top heavy so it flips over quite easily!

Thank you everyone for your kind comments. I will try to take a video soon (work is very busy at the moment). I have also submitted this MOC to Rebrickable for anyone that want's to see the full parts list. If you notice any errors in the parts, please let me know.