Doug72

Now built pair of "really Wacky Wheels" which work OK plus a bespoke compact studless subtractor drive / steering unit. The 3rd wheel will be a castor. Have yet to figure out a suitable 3rd function.

Started developing a Wacky wheel that will be able to climb stairs and step over obstructions.

Perhaps there should be a seperate sub forum for such vehicles, likewise a sub forum for GBC modules.

The subtractor unit looks very compact. A very ingenoius build, well done.

I am considering making my next MOC based on one of these. Power Dozer: High lift platform: with extending arm based on the 42009 crane jib with 3 function steering based on Class Xerion 42054 Modern bucket chain excavator:

Note box graphics say RC not PF is this the new disignation for power Functions now ? Great review and I definitly won't be buying this set. Looks flashy but crane looks tiny compared to the rest of the vehicle and playability poor due power limitations / drive train etc as shown in review.

OK on iPad

The clicking indicates the L.A. has reached the end of its travel or the load is too heavy, so then switch off the motor until you need to reverse the unit - simple.

Is this the topic you are looking for ? When I first started building GBC's I used glass marbles with succes but they are heavy compared to Lego compatible balls, then got some 14 mm beads from Etsy on eBay, finally got balls from PV production.

Re LEGO Worm Gear 1 Module for Angled Gear (27938) Whilst checking this I found there is a gap at all possible alignments between two adjacent worm gears, sufficient to cause problems engaging with a rack gear. Also found another problem in that the new worm teeth does not engage to full depth with the driven angled gear so under high loadins there is a possibillity of the gears skipping. The LEGO Worm Gear with Old Axle (4716) does engage to full depth with the driven gear See image which shows this difference.

There wasn't any before (fixed frame) but there is now and they pivot.

Correct the build is still evolving ! Now proved that the location of the 3 wheel arrangement and track sprocket centres works OK. Will see if I can devise pivoted mounting for the triangular frames for one track unit and compare with fixed rollers set up. Watch this space !! Undecided at the moment - a posssible clue is in my BCE post. Once decided I will start a new topic. Intention is to build a base track unit with turntable that many different types of heavy plant can be mounted on. The drive for the tracks will possibly use a subtractor drive , if enough space using XL or L for drive & M motor for steering..

After a lot of build, reject, re-build have finally come up with an viable track unit for my next MOC. Originally the sprocket axle centres was 21L but the track was either too tight causing the support frames to bow or if I added an extra tread the track kept slipping off the rollers as it was too slack.. By reduceing this to 20L the track tension is now good with all rollers fully supporting the treads without resorting to a track tensioning device. Now to build the other track unit and connect them together. Side View: Rear View: Overhead view:

Thanks, I have tried many permutations but so far none have proved satisfactory. I am continuing to explore more ideas on how to support the large sprocket wheels and rollers. Yes I have tried using those wheels & triangular frame but need to order more rubber tires. Have also tried using the larger disc wheels with pin hole.

t Sorry but only have thumbnail image. For my next planned MOC I want to use the arrangement shown above for the caterpillar tracks but so far have been unable to find a workable solution. The problem is getting the two bogies with the 3 rollers correct so they support the track but don’t cause it to bump as it passes under & over the rollers. Technic wheels are either to small a diameter causing parts & axles to rub on the track tread centre section, other are too large a diameter, meaning the track is not straight between the two large sprocket wheels. Using wedge wheels makes the track unit too high. The Lego rubber track is not long enough. The problem with using large sprockets is the framing required to support them at each end plus the bogies inbetween, if they were only 1L wide as per the small sprocket wheels, building would be simpler. The length of the tracks has to be long enough to able to install a turntable ring of new BWE gear quadrants above the tracks. Has anyone got solutions to achieve constructing this type of caterpillar tracks ?