doug72

Is it permissible to use a large rubber band as a tire around a large diameter wheel ? I have an idea to build a wacky wheeled tank.

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 ?

Make sure the tiny black c/o switches (with 3/4 circle logo) next to the sqaure red buttons is in either full forward or full backwards postion. If it is the inbetween RC won't send a signal.

All PF components need to be treated gently when installing and removing. i.e. DON’T use the cable to disengage the connectors. I use a small pair of pliers to grip the female connector to disengage it from the male part. Make sure there no sharp bends in the cable especially close to the point where it enters the motor or PF receiver. Don’t strain the cable if it slightly too short - use an extension cable. Store PF components separate from other Lego parts. Make sure the contacts on the connector male and female parts are contacting OK , if in doubt use a small screwdriver or needle point to ease then out slightly and retry. Treated this way you will prolong the life of PF components.

Thanks, I still working on it to improve the turntable, slewing and weight distribution.

Does anyone know the maker of this machine ? Possible contender for my next MOC using the old large Lego chain links for the bucket chain I can't find it anymore on google search.

Many thanks for your comment, it has been an epic build and my largest yet. Leant a lot of new technics & solutions during the build without resorting to non lego parts except the hoist rope cord which is used for hanging picture frames, it's really strong. Still room for improvement and have already installed two layers of gear quadrants eliminating fouling of the slewing gear on the battery box. Balls are loaded by hand at the moment but working on a way for buckets to pick them up, think it will be the hardest problem to resolve.

A simple solution is to use thin nylon washer to take up the slack of the worm gear and use the latest version of 8T gear.

Thanks, yes a pile driver had crossed my mind. I have an 4mm scale model somewhere of an Hitachi KH180 drop hammer pile driver and have enough parts to build a Lego version. Found it but rubber tracks have perished on my model ! It has an interesting drop hammer auto release mechanism. Images of 4mm scale model.

Thnaks for the comment, at the moment I need to tidy up after the build and get all my spare parts back into correct boxes etc. The MOC evolved and although it functions OK there is room for improvements. Have idendified a few weak areas in the build and have already starting to improve the base stucture and drive for the caterpillar tracks. It will use a double layer of gear quadrants to give an improved surface for the rotating structure support wheels to roll along, provide a more rigid base and stop the slewing gear fouling on the battery box. Next project, ? Open to ideas and I search on YouTube for unusual machines as possible MOCs. Have eight BWE buckets spare looking for something to do !

My BCE uses a 12t gear meshing with BWE gear ring. The 12 T gear is driven by the new worm gear meshing with a 20T gear giving a very smooth rotation with very 'little backlash. Overall gear ratio = 233:1